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Questions and Answers

What type of hair follicle is characterized by one hair per follicle opening?

  • Complex follicles
  • Simple follicles (correct)
  • Compound follicles
  • Dual follicles

    • Which layer of the epidermis is primarily responsible for forming the major barrier to the outside environment?

  • Stratum spinosum
  • Stratum granulosum
  • Stratum corneum (correct)
  • Stratum basale

    • Hyperkeratosis refers to the thickening of which layer of the skin?

  • Stratum corneum (correct)
  • Hypodermis
  • Stratum spinosum
  • Stratum granulosum

    • Which type of gland secretes directly into the hair follicle?

    <p>Apocrine glands</p> Signup and view all the answers

    In which epidermal layer does cellular differentiation and keratinization begin?

    <p>Stratum spinosum</p> Signup and view all the answers

    Which of the following hormones does NOT affect the secretion of sebaceous glands?

    <p>Insulin</p> Signup and view all the answers

    How many layers thick is the stratum granulosum in haired skin?

    <p>One layer thick</p> Signup and view all the answers

    Where are eccrine sweat glands typically located?

    <p>On the surface of the skin</p> Signup and view all the answers

    What is the primary cause of demodicosis in dogs?

    <p>The follicular mite Demodex canis</p> Signup and view all the answers

    Which of the following statements accurately describes juvenile-onset generalized demodicosis?

    <p>It usually begins with localized lesions</p> Signup and view all the answers

    Which conditions are NOT associated with adult-onset demodicosis?

    <p>Genetic predisposition</p> Signup and view all the answers

    What is the primary reason demodicosis can be frustrating for dog owners?

    <p>It can be very difficult to cure</p> Signup and view all the answers

    What is the life cycle stage of the Demodex mite that is NOT present on the host's skin?

    <p>Twelve-legged adult</p> Signup and view all the answers

    What should be observed during a reexamination for signs of worsening demodicosis within 3 weeks?

    <p>Increase in numbers of mites or new lesions</p> Signup and view all the answers

    Which of the following is NOT a stage in the life cycle of the Demodex mite?

    <p>Four-legged larvae</p> Signup and view all the answers

    What is the main differential diagnosis you should consider with folliculitis?

    <p>Bacterial pyoderma</p> Signup and view all the answers

    What is the typical duration of the life cycle in dogs affected by demodicosis?

    <p>20 to 35 days</p> Signup and view all the answers

    Which areas of a dog are most likely to be infested with mites during nursing?

    <p>The muzzle and forelegs</p> Signup and view all the answers

    What is a common clinical sign associated with generalized demodicosis?

    <p>Large areas of alopecia, usually nonpruritic</p> Signup and view all the answers

    What condition is NOT typically considered when diagnosing demodicosis?

    <p>Cardiac arrhythmia</p> Signup and view all the answers

    What is suggested if rechecks show lesions are spreading or mite counts are increasing?

    <p>The disease is progressing toward becoming generalized</p> Signup and view all the answers

    Which organisms are commonly associated with secondary pyoderma in cases of demodicosis?

    <p>Staphylococcus pseudintermedius</p> Signup and view all the answers

    What is a noteworthy characteristic of the skin in dogs with chronic demodicosis?

    <p>It becomes gray or hyperpigmented</p> Signup and view all the answers

    What factor is believed to contribute to the occurrence of demodicosis in dogs?

    <p>T-cell function abnormality</p> Signup and view all the answers

    Which of the following treatments is appropriate for localized dermatological conditions?

    <p>Weekly lime sulfur dips</p> Signup and view all the answers

    Which of the following is true about Demodex gatoi?

    <p>It lives in the stratum corneum.</p> Signup and view all the answers

    What is a common treatment duration for oral antibiotics in the case of deep pyoderma?

    <p>4 to 8 weeks</p> Signup and view all the answers

    Which of the following is an appropriate action for generalized dermatological conditions?

    <p>Base antibiotic choice on culture results</p> Signup and view all the answers

    What is a key characteristic of dermatophytosis?

    <p>It involves fungal organisms invading keratinized structures.</p> Signup and view all the answers

    Which of the following is a first-line topical treatment for superficial pyoderma?

    <p>Chlorhexidine or benzoyl peroxide shampoos</p> Signup and view all the answers

    What should be continued after complete clinical remission of lesions in pyoderma treatment?

    <p>Antibiotic therapy for 7 days</p> Signup and view all the answers

    Which of the following is a common cause of pruritus in dermatological conditions?

    <p>All of the above</p> Signup and view all the answers

    What is the primary hallmark of the disease discussed?

    <p>Pruritus</p> Signup and view all the answers

    Which of the following statements is true regarding allergy testing?

    <p>It identifies allergens rather than diagnosing the condition.</p> Signup and view all the answers

    What is the recommended approach when treating this condition?

    <p>Avoid known allergens when possible.</p> Signup and view all the answers

    Why is diagnosis considered a diagnosis of exclusion?

    <p>Other skin diseases have similar symptoms.</p> Signup and view all the answers

    What can be combined with antihistamines to reduce corticosteroid dosage?

    <p>Fatty acids</p> Signup and view all the answers

    Which of the following is NOT typically seen with lesions from this condition?

    <p>Fungal infection exclusively</p> Signup and view all the answers

    Corticosteroids are recommended to be used:

    <p>Very judiciously and correctly.</p> Signup and view all the answers

    Which of the following describes a frequent complication associated with self-trauma lesions?

    <p>Secondary bacterial and yeast infections</p> Signup and view all the answers

    What precautions should be taken when considering ivermectin for treatment in certain dog breeds?

    <p>Use only in dogs proven negative for heartworms, particularly in collies and shelties.</p> Signup and view all the answers

    Which of the following describes the primary reason for reserving ivermectin treatment?

    <p>The treatment can have severe side effects, including coma and death.</p> Signup and view all the answers

    What characteristic distinguishes the treatment dosage of milbemycin compared to standard heartworm medication?

    <p>It is significantly higher than the standard heartworm preventive dose.</p> Signup and view all the answers

    What type of conditions should ivermectin be primarily used for?

    <p>Mitaban treatment failures or infeasibility of Mitaban.</p> Signup and view all the answers

    What serious side effect is associated with ivermectin treatment?

    <p>Mydriasis, ataxia, coma, and potential death.</p> Signup and view all the answers

    Why is it important to confirm a dog is heartworm negative before administering milbemycin?

    <p>Administering it without confirmation can lead to severe reactions.</p> Signup and view all the answers

    What factor contributes to the concern surrounding the use of ivermectin in certain dog breeds, specifically regarding the mdr-1 gene?

    <p>The gene deletion increases sensitivity to certain medications.</p> Signup and view all the answers

    What is a common misconception regarding the use of ivermectin for dogs?

    <p>It is FDA-approved for all dog breeds.</p> Signup and view all the answers

    What is a characteristic of chronic demodectic pododermatitis in dogs?

    <p>May have persistent foot lesions after therapy</p> Signup and view all the answers

    What is the recommended method for diagnosing demodicosis?

    <p>Multiple deep skin scrapings or hair plucks</p> Signup and view all the answers

    Which antibiotic therapy should be initiated for secondary pyoderma in demodicosis?

    <p>Bactericidal antibiotics based on culture and sensitivity</p> Signup and view all the answers

    What should be done to enhance the efficacy of Mitaban dips for treating canine demodicosis?

    <p>Use Mitaban dips every week</p> Signup and view all the answers

    What underlying conditions should be investigated in dogs with adult-onset demodicosis?

    <p>Underlying immunosuppressive diseases</p> Signup and view all the answers

    What is the unique aspect of demodicosis that may complicate its treatment?

    <p>It can be recurrent and refractory to therapy</p> Signup and view all the answers

    Which of these conditions is typically NOT associated with demodicosis in dogs?

    <p>Chronic otitis media</p> Signup and view all the answers

    Which treatment method for demodicosis is uniquely FDA-approved?

    <p>Mitaban dips</p> Signup and view all the answers

    Which of the following describes the zoonotic nature of certain infections?

    <p>They can be transmitted via contact with infected hosts.</p> Signup and view all the answers

    What is the treatment protocol for cats diagnosed with dermatophytosis?

    <p>Whole body treatments are required for all infected cats.</p> Signup and view all the answers

    In what situation should multiple lesions on a cat be treated?

    <p>With weekly whole-body treatments like lime sulfur dips.</p> Signup and view all the answers

    Which of the following species is most commonly associated with dermatophytosis?

    <p>Microsporum canis</p> Signup and view all the answers

    What clinical sign is associated with fungal kerions in dermatophytosis?

    <p>Development of fungal furunculosis.</p> Signup and view all the answers

    What is a key treatment consideration when managing infections caused by Microsporum gypseum?

    <p>All in-contact pets should be treated simultaneously.</p> Signup and view all the answers

    What is the characteristic size difference between Demodex cati and Demodex canis?

    <p>Demodex cati is smaller than Demodex canis</p> Signup and view all the answers

    What might be a consequence of not avoiding corticosteroid combination treatments in dermatophytic infections?

    <p>Infection may worsen due to immune suppression.</p> Signup and view all the answers

    Which of the following describes the lesions associated with juvenile-onset generalized demodicosis?

    <p>Lesions present with scaling and alopecia in multiple regions</p> Signup and view all the answers

    What is the primary method for diagnosing demodicosis?

    <p>Skin scrapings to identify mites</p> Signup and view all the answers

    Which of the following is NOT commonly seen in a clinical examination of a cat with pruritic conditions?

    <p>Increased skin thickness.</p> Signup and view all the answers

    What is a common secondary condition associated with Malassezia dermatitis?

    <p>Bacterial folliculitis</p> Signup and view all the answers

    Which form of pyoderma is restricted to the upper layers of the skin?

    <p>Superficial pyoderma</p> Signup and view all the answers

    What type of treatment is typically recommended for surface pyoderma?

    <p>Clipping and cleansing the lesion</p> Signup and view all the answers

    What is the significance of allergen-specific IgE in the context of allergic reactions?

    <p>It helps in cross-linking receptors on mast cells.</p> Signup and view all the answers

    Which area is least likely to be affected by pruritus in animals with Malassezia dermatitis?

    <p>Tail base</p> Signup and view all the answers

    What is commonly observed in cases of generalized demodicosis?

    <p>Systemic disease and immunodeficiency</p> Signup and view all the answers

    Which classification of pyoderma is characterized by erosion with secondary colonization?

    <p>Surface pyoderma</p> Signup and view all the answers

    What treatment is commonly used for managing scabies in cats?

    <p>Revolution (selamectin)</p> Signup and view all the answers

    When is breeding discouraged in cases of demodicosis?

    <p>In juvenile-onset cases with high mite counts</p> Signup and view all the answers

    What clinical sign is commonly observed in cases of Malassezia dermatitis?

    <p>Lichenification</p> Signup and view all the answers

    At what age do clinical signs for certain skin conditions typically begin to manifest?

    <p>Between 1 and 3 years</p> Signup and view all the answers

    What is a characteristic that differentiates the immune response in allergic animals from non-allergic animals?

    <p>Increased IgE production</p> Signup and view all the answers

    Which of the following is a common initial requirement for the development of clinical signs in atopy?

    <p>Past sensitization to the allergen</p> Signup and view all the answers

    What role do Langerhans cells play in the immune system?

    <p>Perform antigen presentation and surveillance</p> Signup and view all the answers

    What is the primary focus of a therapeutic plan for dermatologic patients?

    <p>Formulating based on diagnostic test results and physical exam</p> Signup and view all the answers

    In the context of hair follicles, what characterizes the telogen phase?

    <p>Most hair is in a resting state</p> Signup and view all the answers

    What common error might occur during the diagnostic planning process?

    <p>Focusing solely on one diagnostic test</p> Signup and view all the answers

    What characteristics differentiate Merkel cells from other skin cells?

    <p>Merkel cells are primarily responsible for sensory reception</p> Signup and view all the answers

    Which of the following hormones can impact hair growth?

    <p>Thyroid hormones</p> Signup and view all the answers

    What is the primary consequence of avoiding 'shotgun' therapy in dermatologic treatments?

    <p>Reduction in potential side effects</p> Signup and view all the answers

    Which of the following best defines a clear aspect of client education in dermatologic care?

    <p>Ensuring clients understand treatment plans clearly</p> Signup and view all the answers

    What component of the skin acts as a barrier against microbial invasion?

    <p>Sweat and lipid barrier</p> Signup and view all the answers

    Which process is NOT directly associated with temperature regulation by the skin?

    <p>Vitamin D synthesis</p> Signup and view all the answers

    What does the skin predominantly store?

    <p>Water, vitamins, and electrolytes</p> Signup and view all the answers

    Which structure is primarily involved in signaling between the skin and the immune system?

    <p>Nerves</p> Signup and view all the answers

    What is the primary function of melanocytes in the skin?

    <p>Producing pigment for UV protection</p> Signup and view all the answers

    Which of the following is NOT a function of the skin?

    <p>Absorption of nutrients</p> Signup and view all the answers

    In localized demodicosis, what is the usual age range in dogs affected?

    <p>3 to 6 months</p> Signup and view all the answers

    What characterizes the lesions associated with folliculitis?

    <p>Circular areas of alopecia with scale</p> Signup and view all the answers

    Which of the following best describes the characteristics of cyclic flank alopecia?

    <p>Truncal alopecia that occurs seasonally</p> Signup and view all the answers

    Which condition involves progressive alopecia with hyperpigmentation of the skin?

    <p>Color-dilution alopecia</p> Signup and view all the answers

    What is a common sequela associated with ceruminous otitis externa?

    <p>Secondary bacterial infections</p> Signup and view all the answers

    Which breed is most commonly associated with cyclic flank alopecia?

    <p>Boxers</p> Signup and view all the answers

    Which of the following is a characteristic clinical sign of hypothyroidism in dogs?

    <p>Progressive alopecia</p> Signup and view all the answers

    What typically distinguishes seborrhea from other skin disorders?

    <p>Nonpruritic unless infected</p> Signup and view all the answers

    Which statement is true regarding color-dilution alopecia?

    <p>It leads to minor hair shaft weakening</p> Signup and view all the answers

    How is hypothyroidism frequently diagnosed in dogs?

    <p>Through blood tests for thyroid hormone levels</p> Signup and view all the answers

    What is a common clinical sign associated with juvenile cellulitis in young dogs?

    <p>Pustules and cellulitis</p> Signup and view all the answers

    Which of the following treatments is sometimes combined with corticosteroids for juvenile cellulitis?

    <p>Pentoxifylline with or without corticosteroids</p> Signup and view all the answers

    What diagnostic procedure is essential to rule out infectious causes when assessing skin conditions in dogs?

    <p>Deep skin biopsy for histopathology</p> Signup and view all the answers

    In diagnosing effusive lesions, which simultaneous infection can often be a concurrent finding?

    <p>Bacterial skin infection</p> Signup and view all the answers

    Which of the following conditions is NOT typically included in the differential diagnoses for nodular skin disorders?

    <p>Skin parasites</p> Signup and view all the answers

    What is a common cause of systemic signs such as pyrexia and lethargy in dogs with juvenile cellulitis?

    <p>Secondary bacterial infection</p> Signup and view all the answers

    Which statement accurately describes the treatment approach for conditions categorized under sterile diseases?

    <p>Depends entirely upon the diagnosis</p> Signup and view all the answers

    What might be recommended regarding the breeding of dogs diagnosed with juvenile cellulitis?

    <p>Recommending against breeding</p> Signup and view all the answers

    Which statement accurately describes the role of allergy testing in diagnosing atopy?

    <p>Allergy testing does not diagnose atopy but identifies allergens.</p> Signup and view all the answers

    What is the main therapeutic use of corticosteroids in the management of this disease?

    <p>Corticosteroids are effective when used intermittently to control symptoms.</p> Signup and view all the answers

    What is the hallmark symptom of the condition described?

    <p>Pruritus</p> Signup and view all the answers

    Which of the following statements reflects the significance of diagnosing this condition as one of exclusion?

    <p>It necessitates that all potential causes of pruritus be ruled out.</p> Signup and view all the answers

    What treatment strategy should be considered for minimizing corticosteroid use?

    <p>Using antihistamines in combination with corticosteroids.</p> Signup and view all the answers

    Which approach is most appropriate when potential allergens for atopy are identified?

    <p>Avoiding allergen exposure whenever possible.</p> Signup and view all the answers

    Secondary infections associated with self-trauma are typically caused by which of the following organisms?

    <p>Both bacterial and yeast infections</p> Signup and view all the answers

    What role do hyposensitization vaccines play in treating this condition?

    <p>They modify the animal's immune response to allergens.</p> Signup and view all the answers

    What is the primary characteristic of a vesicle in dermatological terms?

    <p>A circumscribed lesion up to 1 cm filled with clear fluid</p> Signup and view all the answers

    Which skin condition is associated with an interruption of the epidermis that does not penetrate the basement membrane?

    <p>Erosion</p> Signup and view all the answers

    What characterizes hyperkeratosis in the context of skin conditions?

    <p>Increased thickness of the stratum corneum</p> Signup and view all the answers

    Which dermal condition is defined by linear defects caused by scratching or biting?

    <p>Excoriation</p> Signup and view all the answers

    What is the significance of lichenification in skin conditions?

    <p>It indicates a thickened skin response to friction or inflammation.</p> Signup and view all the answers

    What is the expected epidermal turnover time in most species?

    <p>21 to 28 days</p> Signup and view all the answers

    Which condition is characterized by a deeper interruption of the epidermis exposing the dermis?

    <p>Ulcer</p> Signup and view all the answers

    Which type of lesion involves thickening of the skin due to pressure or friction?

    <p>Callus</p> Signup and view all the answers

    What is a potential serious side effect of ivermectin treatment?

    <p>Mydriasis</p> Signup and view all the answers

    Why is caution advised when using ivermectin in certain dog breeds?

    <p>They may have a defect in the mdr-1 gene</p> Signup and view all the answers

    Under what condition should ivermectin be reserved for treatment?

    <p>Mite infestations not responding to other treatments</p> Signup and view all the answers

    Which of the following statements is true regarding the use of milbemycin?

    <p>It should only be used in dogs proven negative for heartworms</p> Signup and view all the answers

    What is the recommended dosing approach when using ivermectin?

    <p>Much higher than the standard Heartgard dose</p> Signup and view all the answers

    What is a common misconception about the use of ivermectin in dogs?

    <p>It is safe for all breeds</p> Signup and view all the answers

    What treatment should be considered before using ivermectin?

    <p>Mitaban</p> Signup and view all the answers

    Which of the following is NOT a noted side effect of ivermectin usage?

    <p>Diarrhea</p> Signup and view all the answers

    What is typically observed in dogs suffering from flea allergy dermatitis?

    <p>Primary papular eruption and pruritus</p> Signup and view all the answers

    Which factor is critical in diagnosing flea allergy dermatitis?

    <p>Compatible clinical signs and flea presence</p> Signup and view all the answers

    Which of the following is a common clinical manifestation in cats with flea allergy dermatitis?

    <p>Generalized alopecia due to excessive grooming</p> Signup and view all the answers

    What type of hypersensitivity reactions are involved in the reaction pattern of flea allergy dermatitis?

    <p>Both type I and type IV hypersensitivity</p> Signup and view all the answers

    What is an important consideration during the treatment of flea allergy dermatitis?

    <p>Implement an aggressive flea control program</p> Signup and view all the answers

    What is a common secondary issue associated with the pruritus caused by flea allergy dermatitis in dogs?

    <p>Secondary pyoderma due to self-trauma</p> Signup and view all the answers

    Which type of flea control product is recommended for effective treatment?

    <p>Adulticidal plus larvicidal or ovicidal products</p> Signup and view all the answers

    What is the concern when using ivermectin for treating flea allergy dermatitis in dogs?

    <p>Potential toxicity in certain breeds</p> Signup and view all the answers

    What is the primary role of the skin's barrier function?

    <p>To provide physical protection and regulate water loss</p> Signup and view all the answers

    Which component is NOT typically included in the main support structure of the epidermis?

    <p>Epidermal cells</p> Signup and view all the answers

    What is a key function of the arrector pili muscles in the skin?

    <p>To aid in thermoregulation</p> Signup and view all the answers

    Which of the following is NOT a typical function of the skin?

    <p>Hormonal secretion</p> Signup and view all the answers

    Which statement accurately describes temperature regulation through the skin?

    <p>Blood vessels can both dilate and constrict for heat preservation</p> Signup and view all the answers

    What is a common clinical sign associated with localized demodicosis in dogs?

    <p>Localized areas of alopecia</p> Signup and view all the answers

    In which aspect is the skin involved in immune communication?

    <p>Communicating via sensory receptors to the lymphatic system</p> Signup and view all the answers

    Which of the following is a function of skin pigmentation?

    <p>Offering protection against ultraviolet light</p> Signup and view all the answers

    What is the typical life cycle duration of Trichodectes canis?

    <p>17 to 21 days</p> Signup and view all the answers

    Which of the following conditions is characterized by an epidermal burrowing mite?

    <p>Sarcoptes scabiei var.canis</p> Signup and view all the answers

    What is a common method to diagnose Trombiculosis?

    <p>Visual identification of adult mites</p> Signup and view all the answers

    Which body areas are typically affected by lesions caused by Sarcoptes scabiei?

    <p>Ear margins and lateral hocks</p> Signup and view all the answers

    What treatment is generally effective in eliminating lice in animals?

    <p>Most flea-control products</p> Signup and view all the answers

    Which species is infested by Felicola subrostratus?

    <p>Cats only</p> Signup and view all the answers

    What type of clinical signs are commonly associated with chigger infestations?

    <p>Severe pruritus and localized lesions</p> Signup and view all the answers

    What distinguishes Cheyletiellosis from other ectoparasite infestations?

    <p>Presence of walking dandruff on fur</p> Signup and view all the answers

    Which statement accurately describes Microsporum canis?

    <p>It can also be caused by species such as Microsporum gypseum.</p> Signup and view all the answers

    What is the primary recommended treatment for a single lesion in cats infected with dermatophytosis?

    <p>Topical antifungal agents without corticosteroids.</p> Signup and view all the answers

    What is a characteristic clinical sign associated with dermatophytosis in cats?

    <p>Scaling and alopecia.</p> Signup and view all the answers

    Which of the following is NOT true regarding cats as carriers of fungal infections?

    <p>Infection usually shows severe symptoms in all cats.</p> Signup and view all the answers

    What is the treatment required for multiple lesions in cats with dermatophytosis?

    <p>Weekly whole-body treatments required.</p> Signup and view all the answers

    Which method is primarily recommended for treating all cats in a household when one is infected?

    <p>Treat all cats in the household together.</p> Signup and view all the answers

    What is a common misconception regarding the treatment of dermatophytosis in cats?

    <p>Combination antifungals are the most effective.</p> Signup and view all the answers

    Which of the following describes a clinical sign that may accompany infections caused by Trichophyton mentagrophytes?

    <p>Presence of fungal kerions.</p> Signup and view all the answers

    What is a common diagnostic method for sebaceous adenitis?

    <p>Skin biopsy for histopathology</p> Signup and view all the answers

    Which breed is most commonly associated with dermatomyositis?

    <p>Shetland Sheepdog</p> Signup and view all the answers

    What is a characteristic clinical sign of plasma cell pododermatitis?

    <p>Painless swelling of the footpads</p> Signup and view all the answers

    What is an outcome of untreated sebaceous adenitis?

    <p>Destruction of melanocytes</p> Signup and view all the answers

    Which treatment is recommended for sebaceous adenitis?

    <p>Antiseborrheic therapy</p> Signup and view all the answers

    Which of the following best describes the clinical onset of dermatomyositis?

    <p>Typically before 1 year of age</p> Signup and view all the answers

    What is an expected feature observed in a skin biopsy for sebaceous adenitis?

    <p>Destruction of sebaceous glands</p> Signup and view all the answers

    What debility is commonly associated with dermatomyositis?

    <p>Atrophy and scarring of muscles of mastication</p> Signup and view all the answers

    What is the primary recommendation regarding the use of corticosteroids in patients being treated with Mitaban?

    <p>Corticosteroids should not be used in these patients.</p> Signup and view all the answers

    Which treatment option is discouraged for localized demodicosis due to the high rate of spontaneous remission?

    <p>Mitaban dip (Amitraz)</p> Signup and view all the answers

    What should be monitored in patients receiving treatment for demodicosis?

    <p>Response to therapy through monthly skin scrapings</p> Signup and view all the answers

    What is the recommended approach for the continuation of Mitaban dipping after achieving two negative skin scrapings?

    <p>Continue for two additional months.</p> Signup and view all the answers

    What is the action of yohimbine in the context of Mitaban treatment?

    <p>It serves as an antidote for Mitaban.</p> Signup and view all the answers

    What is a key recommendation regarding female dogs undergoing treatment for demodicosis?

    <p>They should be spayed when the disease is under control.</p> Signup and view all the answers

    Which of the following statements is true regarding Amitraz and other MAOI inhibitors?

    <p>Amitraz should not be used if the dog is taking Anipryl or other MAOIs.</p> Signup and view all the answers

    What is a recommended non-medicinal method to aid in the treatment of demodicosis?

    <p>Ensuring nutritional improvement and eliminating stress factors</p> Signup and view all the answers

    What is the primary characteristic that distinguishes a diagnosis of atopy from other skin diseases?

    <p>Pruritus is the hallmark symptom</p> Signup and view all the answers

    What is indicated by the usage of allergy testing in cases of suspected atopy?

    <p>Identifying the specific allergens affecting the animal</p> Signup and view all the answers

    Which treatment method is the primary recommendation for managing allergy symptoms in pets?

    <p>Corticosteroids for immediate relief</p> Signup and view all the answers

    What is the purpose of hyposensitization vaccine therapy in the context of allergy management?

    <p>To gradually desensitize the animal to specific allergens</p> Signup and view all the answers

    In addressing self-trauma lesions, what complication is frequently observed?

    <p>Development of chronic infections</p> Signup and view all the answers

    Why is careful administration of corticosteroids necessary during treatment?

    <p>To manage potential side effects effectively</p> Signup and view all the answers

    What approach should be taken when pruritus is observed in an animal to confirm the diagnosis of atopy?

    <p>Exclusion of all other pruritic conditions</p> Signup and view all the answers

    What should be included in a comprehensive treatment plan for an animal with atopy?

    <p>Antihistamines combined with corticosteroids for lower dosages</p> Signup and view all the answers

    Which of the following is a characteristic feature of contact dermatitis?

    <p>Cell mediated hypersensitivity reaction</p> Signup and view all the answers

    What is the primary goal of treating secondary keratinization disorders?

    <p>To manage and treat underlying allergic or endocrine disorders</p> Signup and view all the answers

    Which of the following treatments is most typically recommended for Schnauzer comedo syndrome?

    <p>Topicals that target follicular seborrhea and bacterial infections</p> Signup and view all the answers

    What is a common clinical sign associated with feline acne?

    <p>Lesions often present as plugged hair follicles</p> Signup and view all the answers

    How is contact dermatitis primarily diagnosed?

    <p>Identifying substances for patch testing based on environmental history</p> Signup and view all the answers

    Which treatment is NOT commonly used for managing secondary bacterial infections in dermatological conditions?

    <p>Vitamin therapy</p> Signup and view all the answers

    In the context of managing allergens, which treatment is essential for contact dermatitis?

    <p>Avoidance of the allergen</p> Signup and view all the answers

    What typically complicates the presentation of contact dermatitis in affected animals?

    <p>Secondary lesions from self-trauma</p> Signup and view all the answers

    What defines a macule in dermatology?

    <p>A circumscribed flat spot up to 1 cm in diameter characterized by a change in color</p> Signup and view all the answers

    Which of the following is considered a secondary lesion?

    <p>Crust</p> Signup and view all the answers

    Which cell type is primarily responsible for immune surveillance and antigen presentation in the skin?

    <p>Langerhans cells</p> Signup and view all the answers

    What phase of hair growth is characterized by a resting state where most of an animal’s hair resides?

    <p>Telogen phase</p> Signup and view all the answers

    What characterizes a papule in dermatological terms?

    <p>A solid elevation up to 1 cm in diameter that can be palpated</p> Signup and view all the answers

    In which condition is hyperpigmentation primarily observed?

    <p>Endocrinopathies</p> Signup and view all the answers

    Which hormone is NOT mentioned as affecting hair growth?

    <p>Growth hormone</p> Signup and view all the answers

    In dermatology, why is it important to avoid 'shotgun' therapy when creating a treatment plan?

    <p>It complicates the diagnosis process.</p> Signup and view all the answers

    What feature distinguishes a plaque from other lesions?

    <p>Elevation caused by an accumulation of papules</p> Signup and view all the answers

    Which lesion is characterized by dilated hair follicles filled with keratin?

    <p>Comedo</p> Signup and view all the answers

    Which skin condition is commonly triggered by chronic low-grade friction or pressure, resulting in reactive changes?

    <p>Pressure sores</p> Signup and view all the answers

    What is typically a direct cause of a primary lesion?

    <p>An underlying disease process</p> Signup and view all the answers

    What is the main purpose of a diagnostic plan in dermatological conditions?

    <p>To rule in or rule out differential diagnoses.</p> Signup and view all the answers

    Which type of cells produce melanin pigment granules and are primarily located in the basal layer of the epidermis?

    <p>Melanocytes</p> Signup and view all the answers

    What is the significance of differentiating between primary and secondary lesions?

    <p>It aids in determining the appropriate treatment approach</p> Signup and view all the answers

    Which of the following is NOT a recognized therapeutic approach in the management of dermatologic patients?

    <p>Broad-spectrum antibiotic therapy</p> Signup and view all the answers

    What is a characteristic clinical sign of Malassezia dermatitis?

    <p>Hyperpigmentation of the skin</p> Signup and view all the answers

    Which of the following statements about allergen-specific IgE production is correct?

    <p>It requires subsequent exposure to a previously encountered allergen.</p> Signup and view all the answers

    Which treatment is commonly used for canine scabies?

    <p>Revolution (selamectin)</p> Signup and view all the answers

    What is typically true regarding the lesions affected by Malassezia dermatitis?

    <p>They primarily affect warm and moist areas of the body.</p> Signup and view all the answers

    Which of the following is NOT commonly associated with the development of clinical signs in allergic reactions?

    <p>Immediate exposure to an allergen</p> Signup and view all the answers

    What is a common misconception regarding the treatment of scabies in cats?

    <p>All in-contact cats should be treated.</p> Signup and view all the answers

    What factor contributes to the secondary nature of Malassezia dermatitis?

    <p>It is caused by the primary infection of Malassezia pachydermatis.</p> Signup and view all the answers

    Which area of the body is least likely to be affected by pruritus in cases of Malassezia dermatitis?

    <p>Tail tip</p> Signup and view all the answers

    Which treatment is recommended for the localized form of dermatological conditions?

    <p>Lime sulfur spray or dip</p> Signup and view all the answers

    What is the minimum duration for continuing antibiotic therapy in the case of deep pyoderma?

    <p>14 days beyond clinical remission</p> Signup and view all the answers

    Which of the following is NOT a differential diagnosis for causes of pruritus?

    <p>Stress-induced alopecia</p> Signup and view all the answers

    For generalized dermatological conditions, what treatment is particularly emphasized?

    <p>Weekly lime sulfur dips</p> Signup and view all the answers

    Which statement accurately describes Demodex gatoi?

    <p>It is a contagious mite that lives in the stratum corneum.</p> Signup and view all the answers

    What antibiotic class is recommended for treating superficial pyoderma?

    <p>Cephalosporins</p> Signup and view all the answers

    What is the primary characteristic of dermatophytosis regarding the affected structures?

    <p>It invades keratinized structures.</p> Signup and view all the answers

    Which of the following treatments is explicitly advised against in the management of pyoderma?

    <p>Short-term corticosteroids</p> Signup and view all the answers

    What is the primary hallmark characteristic of the disease discussed?

    <p>Pruritus</p> Signup and view all the answers

    Which of the following is considered critical for the diagnosis of this condition?

    <p>Exclusion of other pruritic skin diseases</p> Signup and view all the answers

    Why is allergy testing performed in this context?

    <p>To determine the specific allergen involved</p> Signup and view all the answers

    When using corticosteroids for treatment, what is the recommended approach?

    <p>To use them sparingly and judiciously</p> Signup and view all the answers

    What is a common complication associated with lesions resulting from self-trauma?

    <p>Secondary bacterial and yeast infections</p> Signup and view all the answers

    In addition to antihistamines, what can be used to lower corticosteroid dosages effectively?

    <p>Fatty acids</p> Signup and view all the answers

    What initial step is advisable when managing allergic reactions leading to this condition?

    <p>Avoiding allergens when possible</p> Signup and view all the answers

    When might it be necessary to perform allergy testing?

    <p>To determine the specific allergens causing a reaction</p> Signup and view all the answers

    What defines a bulla in dermatology?

    <p>A vesicle larger than 1 cm in diameter</p> Signup and view all the answers

    What is the primary characteristic of a wheal?

    <p>Circumscribed, raised lesion consisting of edema</p> Signup and view all the answers

    Which type of lesion is classified as a nodule?

    <p>A small circumscribed solid elevation greater than 1 cm</p> Signup and view all the answers

    What distinguishes a cyst in dermatological terms?

    <p>An epithelial lined cavity filled with fluid or solid material</p> Signup and view all the answers

    In the context of dermatology, what does the term 'primary lesion' refer to?

    <p>A clinical sign directly caused by the disease process</p> Signup and view all the answers

    What is one of the primary functions of the skin in relation to temperature regulation?

    <p>Dilation and constriction of blood vessels</p> Signup and view all the answers

    Which component is NOT typically part of the skin's support structure?

    <p>Epidermal cells</p> Signup and view all the answers

    Characteristic of historical data collection, what is an essential factor in obtaining patient history?

    <p>Documenting whether symptoms are seasonal or nonseasonal</p> Signup and view all the answers

    What type of conditions is referred to as 'color-dilution alopecias'?

    <p>Genetic conditions affecting pigmentation and hair loss</p> Signup and view all the answers

    Which process does the skin NOT participate in as part of its functions?

    <p>Regulation of metabolic rate</p> Signup and view all the answers

    What type of dog breeds are often associated with atopy?

    <p>Terriers and cocker spaniels</p> Signup and view all the answers

    How does the skin contribute to the barrier function?

    <p>By preventing microbial invasion</p> Signup and view all the answers

    In what way does the hair coat assist the functions of the skin?

    <p>Providing insulation and warmth</p> Signup and view all the answers

    What is a common characteristic of localized demodicosis in dogs?

    <p>Alopecia with minimal pruritus</p> Signup and view all the answers

    Which of the following substances is stored in the skin?

    <p>Water and electrolytes</p> Signup and view all the answers

    What is NOT a component of skin secretion functions?

    <p>Keratin production</p> Signup and view all the answers

    Which of the following conditions is NOT included in the differential diagnoses for folliculitis?

    <p>Eczema</p> Signup and view all the answers

    What is a typical feature of generalized demodicosis in dogs?

    <p>Progression to affect multiple body parts if untreated</p> Signup and view all the answers

    What stage of the Demodex mite is responsible for reproduction?

    <p>Eight-legged adult</p> Signup and view all the answers

    What is NOT associated with adult-onset demodicosis?

    <p>High mite counts in young dogs</p> Signup and view all the answers

    What common observation might indicate a worsening case of demodicosis during a reexamination?

    <p>Increase in numbers of mites or new lesions</p> Signup and view all the answers

    Which statement about the life cycle of the Demodex mite is false?

    <p>The adult stage of Demodex mites can migrate off the host</p> Signup and view all the answers

    What is the primary reason generalized demodicosis can be particularly challenging to treat?

    <p>High likelihood of hereditary predisposition and difficulty in management</p> Signup and view all the answers

    What is the primary factor that can complicate the treatment and resolution of otitis when cerumen is produced in abnormal amounts?

    <p>Excessive wax buildup</p> Signup and view all the answers

    Which factor is NOT commonly associated with the development of demodicosis in dogs?

    <p>Decreased grooming habits</p> Signup and view all the answers

    What is the recommended duration for treatment following clinical cure and negative fungal cultures?

    <p>Two weeks</p> Signup and view all the answers

    Which of the following is NOT a primary cause of otitis externa?

    <p>Bacterial infections</p> Signup and view all the answers

    Which condition is characterized by noninflammatory alopecia and symmetric, bilateral hair loss but spares the head and extremities?

    <p>Endocrine alopecia</p> Signup and view all the answers

    What is a noted complication regarding self-medication with endogenous cortisol?

    <p>Poor wound healing</p> Signup and view all the answers

    What defines the anatomy included in otitis media?

    <p>Tympanic membrane, auditory tube, and ossicles</p> Signup and view all the answers

    Which secondary factor might be treated in the management of otitis?

    <p>Underlying allergies</p> Signup and view all the answers

    In males, which condition can result from hyperestrogenism?

    <p>Feminization</p> Signup and view all the answers

    What is a common characteristic of hyperandrogenism in pets?

    <p>Hyperplasia of perianal and tail glands</p> Signup and view all the answers

    Which statement correctly describes otitis media?

    <p>It can extend from otitis externa through the tympanic membrane.</p> Signup and view all the answers

    Which of the following treatments is used for fungal infections in cats?

    <p>Griseofulvin</p> Signup and view all the answers

    What role does cerumen play in the ear canal?

    <p>Traps foreign materials and can contribute to otitis complications</p> Signup and view all the answers

    What symptom is most likely to indicate the presence of otitis externa?

    <p>Itching or pain in the external ear canal</p> Signup and view all the answers

    What is a noted environmental control measure for recurrent infections in pets?

    <p>Environmental decontamination</p> Signup and view all the answers

    Which process is important to observe during the diagnosis of otitis externa?

    <p>Observation of abnormal tympanic membrane</p> Signup and view all the answers

    What is a notable side effect when using griseofulvin in treatment?

    <p>Many side effects</p> Signup and view all the answers

    What term best describes a flat lesion not exceeding 1 cm in diameter, with a change in color?

    <p>Macule</p> Signup and view all the answers

    Which of the following describes the formation of a larger, flat-topped elevation formed by the extension or collection of papules?

    <p>Plaque</p> Signup and view all the answers

    Which type of lesion is primarily caused by self-trauma or inflammation rather than a specific underlying disease?

    <p>Secondary lesion</p> Signup and view all the answers

    What is the correct definition of a papule in dermatological terms?

    <p>Solid elevation up to 1 cm</p> Signup and view all the answers

    Which primary lesion is characterized by the accumulation of loose fragments of the stratum corneum?

    <p>Scale</p> Signup and view all the answers

    Which of the following lesions is correctly described as having a characteristic of being filled with pus?

    <p>Pustule</p> Signup and view all the answers

    Which type of hyperpigmentation is indicated by increased pigmentation in the epidermal or dermal layers?

    <p>Hyperpigmentation</p> Signup and view all the answers

    What is the classification of lesions that are not specifically tied to an underlying disease process?

    <p>Secondary lesions</p> Signup and view all the answers

    What clinical sign is typically observed in generalized demodicosis?

    <p>Large areas of alopecia that are usually nonpruritic</p> Signup and view all the answers

    Which factor is believed to contribute to the onset of demodicosis in dogs?

    <p>T-cell function abnormalities</p> Signup and view all the answers

    What is a major differential diagnosis when assessing demodicosis?

    <p>Dermatophytosis</p> Signup and view all the answers

    During initial assessments in demodicosis cases, which clinical observation is crucial?

    <p>Detecting lymphadenopathy regardless of pyoderma</p> Signup and view all the answers

    In which stage of the Demodex life cycle do the mites primarily cause disease symptoms?

    <p>Adult stage</p> Signup and view all the answers

    What is one of the first sites of infestation in puppies during nursing?

    <p>The muzzle and forelegs</p> Signup and view all the answers

    What is the typical duration of treatment re-evaluation for demodicosis if no improvement is noted?

    <p>3 to 4 weeks</p> Signup and view all the answers

    What is a common misconception regarding the transmission of demodicosis?

    <p>It is not considered a contagious disease</p> Signup and view all the answers

    Which clinical sign is typically seen in dogs affected by Ctenocephalides felis hypersensitivity reaction?

    <p>Primarily papular eruption</p> Signup and view all the answers

    Which of the following treatments is primarily advised for controlling pruritus caused by Ctenocephalides felis?

    <p>Antiparasitic lime sulfur dip</p> Signup and view all the answers

    What is the main diagnostic criterion for identifying hypersensitivity to flea saliva?

    <p>Positive reaction to flea saliva with intradermal injection</p> Signup and view all the answers

    In which areas are cats most commonly afflicted by the dermatitis associated with Ctenocephalides felis?

    <p>Neck, head, and tail base</p> Signup and view all the answers

    What condition is commonly associated with self-trauma from pruritus in dogs affected by Ctenocephalides felis?

    <p>Secondary pyoderma</p> Signup and view all the answers

    What key characteristic distinguishes the type of hypersensitivity reaction associated with Ctenocephalides felis?

    <p>Both type I and type IV hypersensitivity are involved</p> Signup and view all the answers

    How should a flea infestation be managed in dogs showing signs of hypersensitivity to fleas?

    <p>Begin aggressive flea control measures to rule out this condition</p> Signup and view all the answers

    Which treatment option should be avoided in at-risk dog breeds when managing flea hypersensitivity?

    <p>Ivermectin SC or orally</p> Signup and view all the answers

    What underlying condition is associated with severe crusting of footpads and systemic illness in older dogs?

    <p>Liver disease</p> Signup and view all the answers

    Which of the following statements accurately describes the clinical features of bullous pemphigoid?

    <p>Involves deep lesions penetrating the epidermal layer</p> Signup and view all the answers

    Which of these treatments has the least chance of success for managing autoimmune skin disorders?

    <p>Immunosuppressive therapy</p> Signup and view all the answers

    What is the primary mechanism by which lupus affects the body?

    <p>Presence of antibodies against nuclear antigens</p> Signup and view all the answers

    Which diagnosis result is expected to be negative in cases of bullous diseases?

    <p>ANA antibodies</p> Signup and view all the answers

    In autoimmune skin disorders, which area is least likely to be affected by lesions?

    <p>Lumbar region</p> Signup and view all the answers

    When diagnosing autoimmune skin disorders, what is the primary laboratory method used?

    <p>Skin biopsy for histopathology</p> Signup and view all the answers

    Which of the following is NOT a function of the skin?

    <p>Nutrient absorption</p> Signup and view all the answers

    Which of the following clinical signs is NOT commonly associated with autoimmune skin disorders?

    <p>Signs of parasitic infection</p> Signup and view all the answers

    What is one of the main structural components making up the support structure for the epidermis?

    <p>Collagen and elastic fibers</p> Signup and view all the answers

    What is primarily regulated by the blood vessels within the skin?

    <p>Cooling and preservation of heat</p> Signup and view all the answers

    Which of the following statements regarding the functions of the skin is accurate?

    <p>Sweat secretion helps in temperature regulation.</p> Signup and view all the answers

    In localized demodicosis, which of the following is a common characteristic observed?

    <p>Limited lesions typically resolve spontaneously</p> Signup and view all the answers

    What type of skin alteration is typically associated with folliculitis?

    <p>Circular areas of alopecia with hyperpigmentation</p> Signup and view all the answers

    Which of the following substances is important for the skin's barrier function?

    <p>Lipids</p> Signup and view all the answers

    Which statement is true regarding temperature regulation in the skin?

    <p>Blood vessels can constrict to preserve heat.</p> Signup and view all the answers

    Study Notes

    Skin Layers

    • The dermis is below the epidermis.
    • The hypodermis or subcutis is the deepest layer of skin.
    • Epidermally derived appendages include:
      • Pilosebaceous structures
      • Eccrine sweat glands
      • Claws

    Epidermis

    • The stratum corneum is composed of several layers of anuclear cornified cells separated by lipids.
    • The stratum corneum acts as a major barrier to the outside world.
    • The stratum granulosum is one layer thick in haired skin and multiple layers in thinly haired skin.
    • The stratum spinosum consists of one to three layers in haired skin.
    • The stratum basale is the bottom layer of skin.

    Hair Follicles

    • Simple hair follicles have one hair per hair follicle opening; common in cattle and horses.
    • Compound hair follicles have multiple hairs from one follicle opening; common in dogs, cats, sheep, and goats.

    Epidermal Glands

    • Sebaceous glands secrete sebum, which is affected by sex hormones, thyroid hormone, cortisol, malnourishment, and fatty acid deficiency.
    • Apocrine glands secrete into hair follicles; common in most domestic animals.
    • Eccrine glands secrete onto the surface of the skin ("sweating").
    • Eccrine glands are found on the footpads of dogs and cats.

    Dermis

    • The dermis is the middle layer of skin.
    • The dermis helps with optimization of health by improving plane of nutrition and deworming.
    • Folliculitis is not genetic or a genetic defect.
    • Folliculitis treatment involves reexamination and rescraping in 3 weeks.

    Demodicosis

    • Demodicosis is an inflammatory parasitic skin disease caused by the follicular mite Demodex canis.
    • Demodicosis can be very difficult to cure, making it frustrating for owners.
    • The demodex mite spends its entire life on the skin of its host.
    • The demodex mite goes through the following four stages:
      • Fusiform egg
      • Six-legged larvae
      • Eight-legged nymph
      • Eight-legged adult
    • The life cycle of a demodex mite takes 20 to 35 days.
    • Mites spread from the mother to the offspring in the first 3 days of life.
    • Nursing provides direct contact for transmission and explains why the muzzle and forelegs are the first sites of infestation.
    • Demodicosis is not contagious between dogs older than a few days.
    • Dogs with demodicosis have an assumed weak link in their immune system, specifically T-cell function.
    • Demodicosis can occur in two forms:
      • Localized demodicosis
      • Generalized demodicosis

    Localized Demodicosis

    • Localized demodicosis appears as solitary lesions, usually nonpruritic, on the head and forelegs.
    • Localized demodicosis is treated with lime sulfur spray or dip.

    Generalized Demodicosis

    • Generalized demodicosis can present in juvenile and adult dogs.
    • Juvenile onset is common between 3 and 12 months.
    • Generalized demodicosis typically starts as localized lesions and progresses to generalized lesions if not treated adequately.
    • Many dogs with generalized demodicosis seem to have a hereditary disposition.
    • Adult onset is usually in dogs over 5 years.
    • Adult onset may be associated with internal disease, malignancy, chronic corticosteroid use, hypothyroidism, or spontaneous or iatrogenic hyperadrenocorticism.
    • If no underlying cause is found, the chances of successfully treating generalized demodicosis are lower.
    • Generalized demodicosis causes large areas of alopecia, erythema, and skin graying or hyperpigmentation.
    • Generalized demodicosis can result in secondary pyoderma, a deep or superficial bacterial infection typically caused by Staphylococcus pseudintermedius, Proteus spp., or Pseudomonas spp.
    • The signs of pyoderma include papules, pustules, crusts, exudation, and peripheral lymphadenopathy.
    • Localized demodicosis can progress to generalized demodicosis if lesions are spreading or mite counts increase.
    • The treatment for generalized demodicosis includes:
      • Correcting any nutritional, parasitic, or other concurrent problems
      • A minimum database for a generalized diagnosis, including feline leukemia virus and feline immunodeficiency virus testing
      • Weekly lime sulfur dips
      • Treating underlying disease
    • Treatment should be repeated and reevaluated in 3 to 4 weeks.

    Feline Demodicosis

    • Demodex gatoi is a contagious mite that lives in the stratum corneum of cats.
    • Demodex gatoi is a contagious (to other cats) and pruritic mite.
    • Demodex gatoi is diagnosed with a broad superficial skin scraping.
    • The treatment for generalized demodicosis includes:
      • Oral antibiotics for 4 to 8 weeks, typically treating for at least 14 days beyond clinical remission
      • Hydrotherapy and topical antimicrobial shampoos

    Feline Pyoderma

    • Feline pyoderma is rare.
    • Feline pyoderma is treated with:
      • Oral antibiotics (typically cephalosporins)
      • Topical antimicrobials (chlorhexidine or benzoyl peroxide containing shampoos)
      • Avoidance of steroids

    Dermatophytosis

    • Dermatophytosis is caused by fungal organisms invading keratinized structures.
    • Dermatophytosis can be self-limiting, depending on the immune status of the host.
    • Dermatophytosis is often caused by self-trauma.
    • Secondary bacterial and yeast infections are common in dermatophytosis.
    • Dermatophytosis is diagnosed by ruling out other pruritic causes of skin disease.
    • Allergy testing (intradermal or serum) determines the allergen, but does not diagnose atopy.

    Dermatophytosis Treatment

    • The treatment for dermatophytosis includes:
      • Avoiding the allergen if possible
      • Hyposensitization vaccine therapy
      • Corticosteroids (used correctly and judiciously)
      • Antihistamines in combination with fatty acids or corticosteroids for lower corticosteroid doses

    Atopic Dermatitis

    • Atopic dermatitis is a common cause of pruritis in dogs and cats.
    • Atopic dermatitis is diagnosed by:
      • Pruritus (the hallmark of the disease)
      • Ruling out other pruritic causes of skin disease
      • This is a diagnosis of exclusion
      • Allergy testing (intradermal or serum)
    • The treatment for atopic dermatitis includes:
      • Avoiding the allergen if possible
      • Hyposensitization vaccine therapy
      • Corticosteroids (used correctly and judiciously)
      • Antihistamines (used in combination with fatty acids or corticosteroids for lower corticosteroid doses)

    Canine Demodicosis

    • Chronic demodectic pododermatitis: A form of generalized demodicosis with persistent foot lesions.
      • May be refractory to therapy
    • Diagnosis: Use deep skin scrapings or hair plucks to visualize mites.
      • Multiple scrapings are recommended.
    • Treatment:
      • Mitaban dips: The only FDA-approved treatment.
        • Weekly dips increase efficacy.
      • Ivermectin: Not FDA-approved for treatment.
        • Use only in dogs proven negative for heartworms.
        • Higher dose than for heartworm prevention.
        • Exercise caution in certain breeds.
      • Milbemycin (Interceptor): Not FDA-approved.
        • Use higher than standard heartworm prevention dose.
        • Use only in dogs proven negative for heartworms.
    • Client Education:
      • Guarded prognosis
      • Long course of therapy.
      • Juvenile-onset cases shouldn't be bred.

    Feline Demodicosis

    • Demodex cati: Similar to Demodex canis but smaller, with slim, oval ova.
    • Localized form: Pruritic alopecia affecting the nose, eyelids & periocular skin.
      • May also have erythema and scaling.
    • Generalized form: Similar to localized but affecting more body regions.
      • Usually associated with systemic disease and immunodeficiency.
    • Diagnosis: Skin scrapings.
      • Negative scrapings don't rule out D. gatoi in pruritic cats.
    • Treatment: 6 weekly lime sulfur dips.
      • Treat all cats in the household.

    Pyoderma

    • Common in dogs: Bacterial folliculitis and furunculosis.
      • Less common in cats.
      • Usually secondary to underlying conditions: allergic disease or endocrinopathy.
    • Staphylococcus pseudintermedius: Most commonly isolated organism.
    • Classifications:
      • Surface pyoderma: Erosion colonized only on the surface. Often secondary to self-trauma.
      • Superficial pyoderma: Restricted to the stratum corneum or opening of hair follicles.
      • Deep pyoderma: Hair follicle infection extending into the dermis and subcutis.
    • Treatment:
      • Surface pyoderma: Clip and clean lesions with dilute chlorhexidine. Avoid occlusive ointments.

    Microsporum canis

    • Common cause: Fungal kerions or dermatophytic furunculosis.
    • Infections: Microsporum canis is most common. M. gypseum or Trichophyton mentagrophytes can also cause infections.
    • Cats: Can be asymptomatic carriers.
    • Treatment:
      • Single lesions: Clip and treat with topical antifungal. Avoid corticosteroid-containing products.
      • Cats: Require whole body treatments.
        • Multiple lesions: Weekly whole-body treatments.
          • Lime sulfur dips
          • Revolution (selamectin)
          • Ivermectin SC or orally
    • Treatment: Treat all in-contact cats.
      • Lime sulfur dip (LymDip)
      • Revolution (selamectin)
      • Ivermectin SC or orally

    Malassezia Dermatitis

    • Common: Secondary yeast infection, often intensely pruritic.
    • Secondary to: Underlying condition.
    • Causative agent: Malassezia pachydermatis
    • Clinical signs: Intense pruritus, lichenified and hyperpigmented skin.
      • Affects axilla, groin, ventral neck, and abdomen.

    Canine Scabies

    • Causative agent: Sarcoptes scabiei
    • Clinical signs:
      • Intense pruritus
      • Alopecia and scaling
      • Papules and crusts
    • Location: Usually located on the ears, elbows, and back of the legs.
    • Diagnosis: Scraping and examining scales from lesions
    • Treatment:
      • Amitraz dips: The only FDA-approved treatment.
      • Ivermectin: Not FDA-approved.
      • Selamectin: Not FDA-approved.

    Hypothyroidism

    • Causes:
      • Hair loss areas of friction or wear.
      • Loss of guard hairs with retention of undercoat.
      • Myxedema
      • Recurrent pyoderma or otitis externa.

    Hyperadrenocorticism

    • Common in: Middle-aged to older dogs.
    • Clinical Signs: Cutaneous atrophy, calcinosis cutis.
      • Diagnosed via superficial skin scrapings.

    Canine Atopy

    • Cause: Animal's immune system reacts abnormally to common environmental allergens.
    • Diagnosis:
      • Intradermal allergy testing
      • Serum allergy testing
    • Treatment:
      • Antihistamines
      • Immunotherapy (allergy shots)
      • Steroid therapy (short-term)
      • Allergen avoidance
      • Omega 3 fatty acids

    Skin Structure

    • Epidermis: Outermost layer of skin
    • Dermal-epidermal junction: Connects epidermis to dermis
    • Dermis: Thickest layer of skin, comprised of collagen, elastic fibers, muscles, blood vessels, and nerves

    Skin Functions

    • Barrier: Prevents water loss and protects against microbial invasion
    • Communication: Senses touch, pain, itch; connects to lymphatic system
    • Temperature regulation: Hair coat provides warmth, blood vessels dilate/constrict for cooling/heat retention, sweat production
    • Secretion: Produces sweat, pheromones, and a lipid barrier
    • Storage: Electrolytes, water, vitamins, protein, and carbohydrates
    • Pigmentation: Ultraviolet light protection
    • Vitamin D production: Synthesizes vitamin D

    Cellular Components of the Epidermis

    • Keratinocytes: Produce keratin, a fibrous protein that provides structural support
    • Langerhans cells: Immune surveillance and antigen presentation, crucial for allergy development
    • Melanocytes: Produce melanin pigment granules, providing skin color and UV protection
    • Merkel cells: Touch receptors, responsible for tactile sensation

    Hair Follicles and Hair

    • Anagen: Hair growth phase
    • Catagen: Transition phase
    • Telogen: Hair resting phase, majority of an animal's hair is in this phase
    • Factors affecting hair growth: Hormones (thyroid, cortisol, sex hormones), nutrition

    Folliculitis

    • Inflammation of the hair follicle
    • Clinical signs: Circular alopecia, scale, hyperpigmentation, papules, pustules, epidermal collarettes
    • Secondary infections: Bacterial or yeast infections are common, and can cause pruritus

    Hypothyroidism

    • Common in medium to large breed dogs, particularly middle-aged dogs
    • Clinical signs: Mental dullness, lethargy, obesity without increased food intake, exercise intolerance
    • Dermatologic signs: Alopecia, alopecic "rat" tail, hyperpigmentation, seborrhea

    Demodicosis

    • Localized demodicosis: Usually affects puppies under one year old, lesions are localized areas of alopecia with minimal pruritus, commonly affects face and forelegs, often resolves spontaneously
    • Generalized demodicosis: Associated with a compromised immune system, progressive alopecia with hyperpigmentation, diagnosed by ruling out other endocrine alopecias.

    Cyclic flank alopecia

    • Seasonal truncal alopecia, typically seen in boxers, English bulldogs, Airedales
    • Hair loss occurs during winter months with regrowth in warmer months

    Color-Dilution Alopecia

    • Associated with diluted coat colors
    • Abnormal melanization creates weak hair shafts prone to breakage

    Pruritic Skin Disorders

    • Flea allergy dermatitis: Major cause of skin disease in dogs, most common cause of pruritus in cats, lesions are secondary to self-trauma
    • Atopic dermatitis: Hereditary allergy, characterized by intense itching and inflammation, commonly affects dogs, signs can vary, secondary infections are common

    Nodular Skin Disorders

    • Lesions suggest infectious causes, neoplasia, or sterile inflammatory processes
    • Diagnosis: Deep skin biopsy with subcutis evaluation, tissue culture to rule out infections
    • Infectious causes: Bacterial infections, fungal infections, atypical mycobacterial infections
    • Neoplasia: Benign or malignant tumors
    • Sterile diseases: Sterile granulomas, sterile nodular panniculitis

    Skin Lesions

    • Vesicle: Small, fluid-filled lesion up to 1 cm in diameter; rare and fragile; often associated with autoimmune or viral diseases
    • Scar: Area of fibrous tissue replacing damaged dermal or subcutaneous tissue
    • Excoriation: Superficial erosion or ulcer caused by scratching or biting
    • Erosion: Interruption of the epidermis that doesn't penetrate the basement membrane; heals without scarring
    • Ulcer: Deeper interruption of the epidermis exposing the dermis; heals with scarring
    • Lichenification: Thickened, firm skin with exaggerated markings caused by friction or inflammation
    • Hyperkeratosis: Increased thickness of the stratum corneum
    • Fissure: Linear defect into the epidermis or dermis caused by disease or injury
    • Callus: Thickened hyperkeratotic lichenified area

    Epidermis

    • Stratum basale: Single layer of columnar cells and melanocytes; responsible for cell division and production of daughter cells
    • Epidermal turnover time: 21 to 28 days in most species; can be shortened by disease, leading to rapid keratinocyte maturation and seborrhea

    Dermis

    • Thickest layer of the skin
    • Composed of collagen, elastic fibers, arrector pili muscles, blood vessels, and nerves

    Functions of the Skin

    • Barrier: Protects against the environment, regulates water loss, and prevents microbial invasion
    • Communication: Senses touch, pain, and itch; communicates with the immune system through the lymphatic system
    • Temperature Regulation: Hair coat provides warmth; blood vessels dilate or constrict to cool or retain heat; sweat and subcutaneous fat contribute
    • Secretion: Produces sweat, pheromones, and lipids for the barrier
    • Storage: Holds electrolytes, water, vitamins, proteins, and carbohydrates
    • Pigmentation: Provides protection from ultraviolet light
    • Vitamin D production

    Folliculitis

    • Inflammation of the hair follicle
    • Characterized by circular alopecia, scale, hyperpigmentation, papules, pustules, and epidermal collarettes

    Demodicosis

    • Localized demodicosis: Typically affects young dogs (3 to 6 months) with localized alopecia, minimal pruritus, and lesions on the face, periocular region, commissures of the mouth, and forelegs; often resolves spontaneously in 6 to 8 weeks
    • Treatment for localized demodicosis: Ivermectin (higher dose than Heartgard, avoid in collies, shelties, and Old English sheepdogs, use with caution for heartworm-negative dogs); Milbemycin (higher dose than heartworm prevention, use only in heartworm-negative dogs)
    • Generalized demodicosis: Affects dogs of any age; lesions may be widespread or localized, with varying degrees of pruritus; more severe form; often requires prolonged treatment
    • Treatment for generalized demodicosis: Oral or topical amitraz (Mitaban); Ivermectin (higher dose, avoid in collies, shelties, and Old English sheepdogs); Milbemycin (higher dose, avoid in heartworm-positive dogs); other treatments may be required depending on severity

    Pyoderma

    • Bacterial follicular and furuncular infections are common in dogs; less common in cats
    • Often associated with Ctenocephalides felis (common flea)
    • Thought to be a hypersensitivity reaction to flea saliva
    • Involves both type I and type IV hypersensitivity reactions
    • Clinical signs: Pruritus, alopecia, scaling, crusting, papules, pustules, and secondary infections
    • Diagnosis: Compatible clinical signs, presence of fleas or flea dirt, response to treatment
    • Treatment: Eliminate flea exposure with adulticidal, larvacidal, and ovacidal products; treat pruritus and secondary infections with antibiotics

    Scabies

    • Caused by Sarcoptes scabiei var. canis mite
    • Highly contagious between dogs through direct contact
    • Mite burrows in the epidermis
    • Can be transmitted to humans, but the infestation is short-lived
    • Clinical signs: Intense pruritus, lesions on ear margins, lateral hocks and elbows, ventral abdomen, and chest; crusting, excoriations, and lichenification
    • Diagnosis: Superficial skin scrapings may be difficult; response to treatment can be diagnostic
    • Treatment: Amitraz (Mitaban) dip; Ivermectin (avoid in collies, shelties, and Old English sheepdogs); systemic or topical insecticides

    Pediculosis (Lice Infestation)

    • Lice are species-specific
    • Transmission occurs via direct contact
    • Diagnosis: Visualization or tape cytology
    • Treatment: Most flea control products; treat all in-contact animals

    Trombiculosis (Chigger Infestation)

    • Adult mites are free-living, but larvae are bright orange and cause pruritus
    • Seasonal distribution: Spring to fall
    • Transmission occurs via direct contact with vegetation
    • Clinical signs: Pruritus, lesions on body areas in contact with vegetation
    • Diagnosis: Visualization of mites
    • Treatment: Frontline (fipronil) spray; most flea sprays or dips are effective

    Cheyletiellosis ("Walking Dandruff")

    • Affects dogs, cats, and rabbits
    • Clinical signs: Pruritic scaling, "walking dandruff," hair loss, alopecia, scabs
    • Diagnosis: Microscopic examination of skin scrapings
    • Treatment: Amitraz (Mitaban); fipronil; selamectin; other topical and systemic insecticides

    Demodicosis

    • Demodicosis is a condition caused by the mite Demodex canis.
    • Localized demodicosis is common and usually resolves spontaneously in 90% of cases. Treatment is usually not required.
    • Avoid using Amitraz (Mitaban dip) for localized demodicosis.
    • Generalized demodicosis is a more serious form of the disease and requires treatment.
    • Treatment for generalized demodicosis:
      • Amitraz (Mitaban dip) is a commonly used treatment.
      • Amitraz is an off-label use for this condition.
      • Amitraz is a monoamine oxidase inhibitor (MAOI).
      • Animals taking MAOIs like Anipryl should not undergo Mitaban dips.
      • Yohimbine serves as the antidote to Mitaban.
      • Monitor the dog's response to therapy using monthly skin scrapings.
      • Continue treatment for one to two months after two negative skin scrapings one month apart.
      • Minimize stress for the dog during therapy.
      • Spaying female dogs with generalized demodicosis is recommended after the disease is controlled. This helps prevent recurrence due to estrus cycles, reduces the risk of pyometra (uterine infection), and lowers the risk of mammary neoplasia (tumors).

    Ringworm

    • Microsporum canis is the most common species of ringworm affecting cats. Other species causing infection include Microsporum gypseum and Trichophyton mentagrophytes.
    • Ringworm is zoonotic, meaning it can be transmitted to humans.
    • Transmission occurs through contact with an infected host, fomites (inanimate objects), or contaminated environments.
    • Clinical signs of ringworm include mild to extensive inflammation, scaling, and alopecia (hair loss).
    • Fungal kerions (dermatophytic furunculosis) can also occur.
    • Cats can be asymptomatic carriers of ringworm.
    • Treatment:
      • Single lesions: Clip and treat with topical antifungal agents. Avoid combination products containing corticosteroids.
      • Cats require whole-body treatments. Do not spot-treat cats.
      • Multiple lesions: Weekly whole-body treatments are necessary.
      • Lime sulfur dip is a commonly used treatment for ringworm.

    Atopy (Allergic Dermatitis)

    • Atopy is a common skin disease in dogs.
    • Clinical signs:
      • Pruritus (itching) is the hallmark of atopy.
      • Pruritus is often severe, leading to skin lesions due to self-trauma.
      • Common areas affected include the face, feet, and abdomen.
      • Secondary bacterial and yeast infections are common.
    • Diagnosis:
      • Rule out other pruritic skin diseases.
      • Atopy is often a diagnosis of exclusion.
      • Allergy testing (intradermal or serum testing) can help determine what the animal is allergic to, but not diagnose atopy.
    • Treatment:
      • Avoid the allergen whenever possible, such as house dust mites.
      • Hyposensitization vaccine therapy can be beneficial.
      • Corticosteroids are effective when used correctly, but should be used judiciously.
      • Antihistamines can be used in combination with fatty acids or corticosteroids to reduce the dosage of corticosteroids needed.

    Seborrhea

    • Seborrhea is a condition characterized by excessive oil production.
    • Primary Seborrhea
      • Primary seborrhea can have an underlying hereditary component.
      • Food allergy is a possible underlying cause of seborrhea.
      • Consider food allergy as a possible differential diagnosis, but it is less likely than atopy.
    • Secondary Seborrhea
      • Secondary seborrhea is caused by underlying conditions, such as allergies or endocrine disorders.
    • Treatment:
      • Topical antiseborrheic shampoos and rinses are helpful.
      • Vitamin A therapy or synthetic retinoid therapy may be used.

    Schnauzer Comedo Syndrome

    • Schnauzer comedo syndrome is a primary localized keratinization disorder.
    • It typically develops in adult Schnauzers.
    • Clinical signs:
      • Multiple plugged hair follicles along the dorsum.
      • Secondary bacterial infections are common.
    • Treatment:
      • Topicals that address follicular seborrhea and bacterial infections are used.

    Feline Acne

    • Feline acne is an idiopathic (unknown cause) localized primary keratinization disorder.
    • Clinical signs:
      • Acne-like lesions commonly occur on the chin, chest, and abdomen.
      • Secondary infections are common.
    • Treatment:
      • Oral and/or topical antibiotics.
      • Topical antiseborrheic agents.

    Secondary Keratinization Disorders

    • Secondary keratinization disorders are common.
    • They result from underlying allergic or endocrine disorders.
    • Treatment:
      • Address the underlying cause to resolve clinical signs.

    Sebaceous Adenitis

    • Sebaceous adenitis is an autoimmune disease.
    • It involves destruction of the sebaceous glands.
    • Breed predisposition: Standard poodle, Akita, Samoyed, vizsla.
    • Clinical signs:
      • Excessive scaling, follicular casts, and patchy alopecia.
      • Secondary bacterial and yeast infections are common.
      • Typically nonpruritic (not itchy).
    • Diagnosis: Histopathology is diagnostic.
    • Treatment:
      • Antiseborrheic therapy.
      • Topical treatments to replace sebum.

    Plasma Cell Pododermatitis

    • Plasma cell pododermatitis is a suspected immune-mediated disease affecting cats.
    • Clinical signs:
      • Soft, painless swelling of the footpads in cats.
      • Multiple footpads and feet may be affected.
    • Diagnosis: Based on clinical signs.
    • Treatment:
      • Steroid therapy is often used.
      • Topical agents are less successful.

    Hypothyroidism

    • Occurs in older dogs.
    • Clinical signs:
      • Hair loss (alopecia) in areas of friction, such as the collar, harness, or pressure points.
      • Loss of guard hairs with retention of undercoat.
      • Myxedema: Increased skin thickness, creating a "tragic" facial expression.
      • Recurrent pyoderma or otitis externa (ear infections).
    • Diagnosis:
      • Refer to small animal endocrinology resources.

    Hyperadrenocorticism (Cushing's Disease)

    • Found mainly in middle-aged to older dogs.
      • Clinical signs:
        • Cutaneous atrophy: Thin epidermis and dermis, with prominent blood vessels.
        • Calcinosis cutis: Calcium deposits in the skin.
        • Many skin lesions are secondary to self-trauma, often due to severe pruritus.
        • Secondary bacterial and yeast infections are very common.
      • Diagnosis:
        • Pruritus is the hallmark of hyperadrenocorticism.
        • It's usually a diagnosis of exclusion.
        • Rule out other causes of pruritus.
        • Allergy testing can help pinpoint the cause of allergic reactions but not confirm the diagnosis of hyperadrenocorticism.
      • Treatment:
        • Avoid the allergen if possible (e.g., house dust mites).
        • Hyposensitization vaccine therapy may be helpful.
        • Corticosteroids are very effective when used carefully and judiciously.
        • Antihistamines can be used alongside fatty acids or corticosteroids to reduce the required corticosteroid dose.

    Dermatomyositis

    • An inherited disorder in certain breeds, particularly Collies and Shetland sheepdogs.
    • Clinical signs:
      • Typically presents before 1 year of age.
      • Alopecia, erythema (redness), erosions, and ulcers with crusts.
      • Myopathy (muscle atrophy) may or may not be present. - Diagnosis:
      • Clinical signs.
      • Skin biopsy for histopathology.
      • Histopathology of ocular tissue is often performed if enucleation (eye removal) is necessary. - Treatment:
      • Manage the uveitis (inflammation of the eye).
      • Skin lesions are cosmetic, and eventually all melanocytes (pigment cells) will be destroyed.

    Physical Examination

    • Using the correct dermatologic terms is crucial
    • Examine ears, feet, mucous membranes, lymph nodes, claws, and footpads
    • Observe if lesions are symmetrical or nonsymmetrical
    • Differentiate between primary and secondary lesions

    Primary Lesions

    • Macule: A flat spot, up to 1 cm in diameter, with a change in color
    • Patch: A macule greater than 1 cm in diameter, not palpable
    • Papule: A solid elevation, up to 1 cm in diameter, caused by cell infiltration, edema, or hypertrophy of the epidermis
    • Plaque: A larger flat-topped elevation formed by extension or collection of papules
    • Pustule: A small circumscribed elevation filled with pus
    • Scale: Accumulation of loose fragments of stratum corneum (keratinocytes)
    • Follicular casts: Accumulation of follicular material adhered to the hair shaft
    • Crust: Dried exudate made up of serum, white blood cells (WBCs), red blood cells, and keratin
    • Hyperpigmentation: Increased epidermal or dermal melanin
    • Hypopigmentation: Loss of epidermal melanin
    • Comedo: Dilated hair follicle filled with keratin and sebaceous secretions (blackhead)

    Secondary Lesions

    • Epidermal collarettes: Circular rim of loosely attached keratin (scale), usually indicative of an area over bony prominences

    Skin Structure

    • Epidermis
      • Basal layer contains melanocytes which produce melanin pigment granules
      • Langerhans cells are responsible for immune surveillance and antigen presentation
      • Merkel cells
      • Inflammatory cells (neutrophils, eosinophils, lymphocytes) when skin is diseased
    • Dermal-epidermal junction
    • Hair follicles and hair
      • Anagen is the hair growth phase
      • Catagen is the transition phase
      • Telogen is the hair resting phase; most of an animal's hair is in this phase
      • Hair growth is affected by hormones, nutrition, and topical antipruritics

    Malassezia Dermatitis

    • Secondary yeast infections are common and intensely pruritic
    • It is always secondary to another underlying condition
    • Caused by Malassezia pachydermatis
    • Signs include intense pruritus, lichenified and hyperpigmented skin, and affects the axilla, groin, ventral neck, and abdomen

    Differential Diagnoses for Malassezia Dermatitis

    • Dermatophytosis
    • Pyoderma
    • Causes of miliary dermatitis
    • Causes of pruritus

    Treatment for Malassezia Dermatitis

    • Localized form: Lime sulfur spray or dip
    • Generalized form:
      • Dependent on the presence of underlying disease
      • A consistent successful therapy has not been reported
      • Weekly lime sulfur dips
      • Treat underlying disease
    • Superficial pyoderma:
      • Oral antibiotics (cephalosporins) 22 to 33 mg/kg every 12 hours for a minimum of 21 days
      • Continue therapy for at least 7 days beyond complete clinical remission of lesions
      • Topical antimicrobials (chlorhexidine or benzoyl peroxide shampoos) every 2-3 days
      • Avoid steroids
    • Deep pyoderma:
      • Oral antibiotics for 4 to 8 weeks; treat for at least 14 days beyond clinical remission
      • Base antibiotic choice on culture and sensitivity results
      • Hydrotherapy and topical antimicrobial shampoos

    Dermatophytosis

    • Fungal organisms invade keratinized structures
    • Can be a self-limiting disease depending on the immune status of the host
    • Diagnosed by superficial skin scrapings

    Demodex gatoi

    • Not a follicular mite; lives in the stratum corneum
    • Broad blunted abdomen rather than a slim elongated one
    • Contagious (to other cats) and pruritic mite

    Treatment for Demodex gatoi

    • Treat all in-contact cats
    • Lime sulfur dip (LymDip)
    • Revolution (selamectin)
    • Ivermectin SC or orally

    Atopy

    • Atopic dermatitis/allergic skin disease/atopy
    • A complex immune-mediated skin disease associated with IgE-mediated hypersensitivity
    • Atopic animals demonstrate exaggerated immune responses to environmental allergens
    • Produces more IgE than a non-allergic animal
    • Clinical signs typically noted between 1 and 3 years of age
    • Requires a second exposure to an allergen following initial exposure
    • Allergen-specific IgE cross-links receptors on mast cells, causing degranulation and clinical signs
    • Clinical signs include seasonal or nonseasonal pruritus, face and feet are primarily affected, chronic otitis externa, lesions from self-trauma, and secondary bacterial and yeast infections
    • Diagnosed by ruling out other pruritic causes of skin disease
    • Allergy testing is used to determine the animal's allergies, not diagnose atopy
    • Treatment includes avoiding the allergen if possible, hyposensitization vaccine therapy, corticosteroids, antihistamines, and fatty acids

    General Assessment of the Dermatology Patient

    • Signalment is important to gather in dermatology cases, including age, breed, sex, and color
    • Breeds have pre-dispositions to certain skin conditions. Terriers are pre-disposed to atopy, while American Cocker Spaniels can be prone to seborrhea
    • Color diluting genes can cause alopecia
    • History is crucial to understand the cause of the skin problem
    • Primary Complaint is the patient's main reason for presentation
    • Obtain History chronologically, including the timing and progression of symptoms such as itching or alopecia
    • Obtain a patient's history asking if symptoms are seasonal or non-seasonal

    Skin Anatomy

    • Epidermis is the outermost layer of skin and is made of a single layer of columnar cells and melanocytes
    • Dermis is the thickest layer of skin, composed of Collagen, elastic fibers, arrector pili muscles, blood vessels, and nerves

    Skin Function

    • Barrier is the skin's primary function, providing physical protection against the environment and microbial invasion
    • Communication through touch, pain, and itch senses helps the immune system communicate with the lymphatic system
    • Temperature Regulation through hair coat insulation, vasodilation, vasoconstriction, sweat, and subcutaneous fat
    • Secretion of substances such as sweat, pheromones, and the lipid barrier
    • Storage of electrolytes, water, vitamins, protein, and carbohydrates
    • Pigmentation shields against ultraviolet light
    • Vitamin D Production

    Folliculitis

    • Inflammation of the hair follicle can cause circular alopecia with scaling, hyperpigmentation, papules, pustules, and epidermal collarettes
    • Demodicosis is caused by the follicular mite Demodex canis
    • Generalized Demodicosis is typically seen in juvenile dogs (3 to 12 months old) and may have a hereditary component
    • Adult Onset Demodicosis (usually older than 5 years) may be associated with internal diseases, malignancies, chronic corticosteroid use, hypothyroidism, or spontaneous or iatrogenic hyperadrenocorticism

    Endocrine and Alopecic Dermatoses

    • Alopecia is usually symmetrical and bilateral, sparing the head and extremities, and is non-inflammatory.
    • Endocrine Alopecias are less common in cats.
    • Alopecia X (follicular arrest) may be due to treatment errors

    Otitis

    • Otitis Externa is inflammation of the external ear canal.
    • Otitis Media is inflammation of the middle ear.
    • Otitis Interna is inflammation of the inner ear
    • Cerumen is waxy debris in the ear canal produced by sebaceous and apocrine glands.
    • Parasites can cause otitis, including Otodectes cyanotis, Otobius megnini, Demodex mites, Eutrombicula alfreddugesi, Sarcoptes scabiei, and poultry mites
    • Allergic Disorders are a common cause of chronic otitis in dogs, especially atopy
    • Otitis Media can be an extension of otitis externa, spreading via a damaged tympanic membrane or the auditory tube
    • Diagnosis of otitis includes physical exam, otic exam, otic cytology, culture and sensitivity (if necessary)

    Skin Lesions

    • Primary lesions are the main clinical signs directly caused by a disease process.
      • Macule is a small, flat, circumscribed spot up to 1 cm in diameter with a change in color.
      • Patch is a larger macule greater than 1 cm in diameter that is not palpable.
      • Papule is a solid elevation up to 1 cm in diameter caused by cell infiltration, edema, or epidermal hypertrophy. It is palpable and often erythematous.
      • Plaque is a larger, flat-topped elevation formed by the extension or collection of papules.
      • Pustule is a small, circumscribed elevation of skin filled with pus.
      • Comedo is a dilated hair follicle filled with keratin and sebaceous secretions (blackhead).
    • Secondary lesions are not specific for the underlying disease process; they may be caused by self-trauma or other inflammatory processes.
      • Epidermal collarettes are circular rims of loosely attached keratin (scale), usually indicative of a pustule.

    Skin Structure

    • The epidermis is the outermost layer of the skin.
      • It is composed of one layer of columnar cells and melanocytes.
    • The dermis is the thickest part of the skin.
    • The subcutaneous layer is made up of collagen, elastic fibers, some muscles (arrector pili muscles), blood vessels, and nerves.

    Skin Functions

    • Barrier
      • Provides physical protection from the environment.
      • Regulates water loss.
      • Protects from microbial invasion.
    • Communication
      • Senses of touch, pain, and itch.
      • Immune system communicates from the skin to the lymphatic system.
    • Temperature regulation
      • The hair coat provides warmth.
      • Blood vessels dilate or constrict to allow for cooling or preservation of heat.
      • Sweat glands and subcutaneous fat assist in temperature regulation.
    • Secretion
      • Sweat, pheromones, and lipid barrier secretion.
    • Storage
      • Electrolytes, water, vitamins, protein, and carbohydrates.
    • Pigmentation
      • Ultraviolet light protection.
    • Vitamin D production

    Folliculitis

    • Inflammation of the hair follicle.
    • A circular area of alopecia with scale and hyperpigmentation is a typical clinical lesion.
    • Papules, pustules, and epidermal collarettes can also be associated with folliculitis.

    Demodicosis

    • Caused by the mite Demodex canis.
    • Mites spread from the bitch in the first 3 days of life.
    • Nursing provides direct contact for transmission, so the muzzle and forelegs are the first sites of infestation.
    • It is not a contagious disease.
    • Dogs with demodicosis have an assumed weak link in their immune system, likely caused by T-cell function abnormalities.
    • Localized Demodicosis:
      • Age younger than 1 year, usually 3 to 6 months.
      • Lesions include alopecia, minimal pruritus, and face/foreleg involvement.
      • 90% resolve spontaneously in 6-8 weeks.
    • Generalized Demodicosis:
      • Large areas of alopecia.
      • Gray or hyperpigmented skin due to chronic inflammation.
      • Secondary pyoderma is common, caused by Staphylococcus pseudintermedius, Proteus spp, or Pseudomonas spp.
      • Clinical signs include papules, pustules, crusts, exudation, and peripheral lymphadenopathy.

    Flea Allergy Dermatitis (FAD)

    • A hypersensitivity reaction to flea saliva.
    • Type I and IV hypersensitivity reactions contribute to the pattern of reaction.
    • Clinical Signs:
      • Pruritus.
      • Tail-head region extending cranially on the dorsum.
      • Inner and caudal thighs.
      • Flexures of the elbows.
      • Secondary pyoderma is common due to self-trauma.
    • Diagnosis - Made through compatible clinical signs, the presence of fleas or flea dirt, presence of tapeworm segments, and a positive reaction to flea saliva with intradermal injection.
      • Aggressive flea control is necessary to rule out FAD even if fleas are not present.

    Pediculosis (Lice Infestation)

    • Lice are species-specific.
    • Linognathus setosus: Dog-sucking louse.
    • Clinical signs:
      • Severe crusting of the footpads, elbows, and commissures of the mouth.
      • Systemic illness associated with liver disease.
    • Diagnosis: Based on signalment, clinical signs, and histopathology.

    Bullous Diseases

    • Bullous Pemphigoid is a bullous disease where the epidermis separates from the dermis.
    • Clinical signs: Identical to pemphigus vulgaris, a serious, often fatal disease.
    • Lesions: Ulcers and crusts.
    • Cytology and histopathology: Acantholytic cells are not found.
    • ANA: Negative

    Lupus

    • Mechanism of disease: Presence of antibodies against nuclear antigens.
    • Diagnosis: Made through skin biopsies for histopathology and lab work, which may include ANA testing.
    • Lesions are typically crusts covering erosions or ulcers in the nasal planum, ear pinnae, and footpads.
    • Similar histopathologic and clinical features can be seen with certain types of demodicosis, particularly Demodex foliaceus which primarily affects the face.

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    Description

    Test your knowledge on the various layers of skin, including the epidermis, dermis, and hypodermis. This quiz covers the structure and function of epidermal appendages like hair follicles and glands. Enhance your understanding of skin anatomy and physiology.

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