Veterinary Lecture Notes on Crust, Scale, Environmental, and Endocrine Dermatosis PDF

Approach to crust, scale, environmental and endocrine dermatosis Dynatra Subasinghe BVSc, PG Dip., MSc, PhD, MRCVS, SFHEA Thursday, 31 August 2023 1 Part 1 - Approach to Diseases characterised by Crust and Scale Lea...

Approach to crust, scale, environmental and endocrine dermatosis Dynatra Subasinghe BVSc, PG Dip., MSc, PhD, MRCVS, SFHEA Thursday, 31 August 2023 1 Part 1 - Approach to Diseases characterised by Crust and Scale Learning Outcomes ✓ Define crust and scale ✓ Identify and recognise the common conditions causing crust and scales ✓ Describe the various diagnostic procedures used to determine aetiology ✓ Discuss approach to appropriate management and treatment of diseases characterized by crust and scales ✓ Discuss appropriate prognosis and welfare implications of management and treatment options ✓ Discuss control measures appropriate for disease prevention where applicable Crust Definition Crust can be composed of cells and dried exudate. scale that combines with other cellular debris May even be dried medications The exudate can be serous (protein and white cells) sanguineous (Blood) purulent (pus) Or Mixed Image source – Muller and Kirk, 2013 Scales Definition Accumulation of loose fragments of the horny layer (cornifield cells) of the skin Normal loss occurs as individual cells or small clusters not visible to the naked eye. Abnormal scaling is the loss in larger flakes. More than 80% of scaling disorders arise from secondary causes Primary – Ichthyosis, primary Seborrhoea – non pruritic Secondary – will be discussed in detail -pruritic/variably pruritic Image source – Muller and Kirk, 2013 Hereditary disorders of the skin Primary disorders of cornification - Hereditary disorders of the epithelium Ichthyosis – abnormal cornification Nasal hyperkeratosis Lamellar ichthyosis in golden retrievers Approach to Diseases characterised by Crust and Scale Secondary - causes Pruritic Non-pruritic / variably pruritic 1. Parasites – Scabies, Cheyletiella, 1. Fungal – Dermatophytosis Demodex, Psoroptes cuniculi 2. Leishmaniasis 3. Sebaceous adenitis 2. Allergy – food, environmental 4. Sterile pustular diseases allergens etc. 5. Zn responsive dermatosis 6. Lethal acrodermatitis 3. Pyoderma – Bacterial infections, 7. Metabolic disorders Staphylococcus spp. 8. Erythema multiforme complex 9. Drug reactions 10. Neoplasia Approach to Diseases characterised by Crust and Scale Clinical approach Depends on the condition and the clinical reasoning Diagnostic tests and treatment trials ❖Cytology -Skin scraping ❖Culture - ABST / Fungal culture ❖Biopsy ❖Skin allergy testing ❖Diet change If food allergy ❖Blood tests - if systemic disease is suspected –serology, FBC, serum chemistry profile, etc. Modified from - https://www.universalmedicalinc.comdownloaded 09-08-18 Parasitic conditions Pruritic dog ? Sever erythema pruritic paw Sever crusting on the tip of the pinna Sarcoptes Image source – Muller and Kirk, 2013 Sarcoptes (slide provides additional details for revision) Dog (Sarcoptes scabei), cats Very pruritic – itching leads to papules and pustules and crust formation Zoonotic - mostly Foxes implicated Diagnosis – know the clinical reasoning!! Better viewed after clipping area Skin scraping - very few mites – difficult to find Serology Treatment – 1. Shampoo - best is to clip the area – help clean better 2. Mite treatments - Selamectin (Stronghold®), Moxidectin ( Advacate®), Isoxazoline (Bravecto® and Simparica®) 3. Antibiotics – if pyoderma complications 4. Steroids or Oclacitinib- calm the pruritus if severe Image source – Muller and Kirk, 2013 Cheyletiella (slide provides additional details for revision) Relatively - species specific mites Cat - Cheyletiella blakei Rabbit – Cheyletiella parasitivorax Dog- Cheyletiella yasguri Diagnosis Clinical signs + walking dandruff May have to clip to see lesions properly Direct viewing of the mite- microscopic examination of the products - superficial skin scrapings, tape preparations, flea combing or Trichogram (view eggs attached to hair) Treatment – difficult to treat very pruritic Treatment of animal and environment. Selamectin (stronghold®), Fipronil spray ( Frontline®) Image source – Muller and Kirk, 2013 Parasitic conditions Causes Parasitic –Psoroptes cuniculi (rabbit) Mites irritate the lining of the ear and cause serum and thick brown crusts to accumulate Source - www.msdvetmanual.com Pruritic causes cd… Allergic conditions When chronic – lesions become thickened with scale formation on the skin Pyoderma – pustules – epidermal collarets then lead to scale and crust Discussed before Conditions with crust and scales Causes Non-pruritic / variably pruritic 1. Fungal – Dermatophytosis 2. Leishmaniasis 3. Sebaceous adenitis 4. Sterile pustular diseases 5. Zn responsive dermatosis 6. Lethal acrodermatitis 7. Metabolic disorders - hypothyroidism 8. Erythema multiforme complex 9. Drug reactions 10.Neoplasia Dermatophytosis Most commonly seen in cats - Microsporum canis Dogs - Trichophyton mentagrophytes and M. canis Environmental contamination – problem in catteries Circular patches of scaling, alopecia, head and ears Zoonotic – important –mainly children Diagnosis Woods lamp – apple green fluorescence – Pros, cons Sampling important – scrapings – microscopic Fungal culture best Treatment – Iitraconazole (Licenced) (cascade) Sources - www.pinterest.de and www. icatcare.org Non-pruritic / variably pruritic Protozoa sandfly Leishmaniasis (Zoonotic) Uncommon in uk Mainly imported rescue dogs- Image source –www.wm-referrals.com, 2013 and www.ecdc.europa.eu Sebaceous adenitis not common Immune mediated disease - Dogs, cats and rabbits Destruction of sebaceous gland – dry skin scaling and alopecia Signalment - Dog breed -standard poodles (young to middle aged), Akitas, Samoyeds Clinical signs Pruritic Bacterial folliculitis Fine white scales Scaling and thinning of the hair Disease to keep in mind ! Setter Rabbit skin Image source – Muller and Kirk, 2013 2013, http://www.medirabbit.com Pemphigus foliaceous Immune mediated sterile pustular diseases that leads to scaling and crusting lesions Discussed earlier Image source – Muller and Kirk, 2013 Non-pruritic / variably pruritic Zn responsive dermatosis Respond to Zn supplementation Type 1- Inability to absorb Zinc from and intestine - Breeds - Alaskan malamute – essential fatty acids Diagnosis Siberian huskies History and signalment Good prognosis Genetic predisposition – Alaskan Clinical signs- crusting malamute, Siberian huskies erythema arround eyes age- 1-3 years old mouth and pressure points Type 2 - Diet deficient in Zn (poor quality)- Histopathology- biopsy other breeds, age- 1-3 years old Plasma low levels of E. g. - Great Dane Zinc Not respond to Zn Lethal acrodermatitis of bull terriers Inherited autosomal recessive trait supplements very young/new born animals Poor prognosis Crusted lesions on ears and muzzle Cracked and crusted foot pads  Non-pruritic / variably pruritic Metabolic disorders (If seen be suspicious and examine further) Hepatocutaneous syndrome Hypothyroidism Older animals usually Facial alopecia and scaling Scaly crusty lesions Discussed later Footpads are often severely thickened and fissured and are often painful. Diabetes truncal hypotrichosis with Thymoma seborrhoea. Dandruff on coat Loss of hair/ scaly lesions Some times dull coat - EPI Mass in cranial mediastinum – unusual Image source – Muller and Kirk, 2013 Erythema multiforme complex Erythematous lesions Hypersensitivity reaction to infections or drugs; may also be caused by cancer or other diseases Rare – but good to be aware Immune mediated group of conditions EM minor- idiopathic, post infection EM major Stevens Johnson syndrome- drug eruption Toxic epidermal necrolysis- cats dog falling apart in front of you Diagnosis – history, clinical signs, rule out other diseases Lesion – various lesions - Erythematous macuoles, papules, plaques, scales and crusts Arranged in annular or polycyclic shapes Treatment – steroids? difficult and controversial, best if can remove underlying cause– poor prognosis Imge source – Kumari et. Al.,2016 Drug reactions Always a possibility History - take a drugs list – inhaled, oral, topical etc. Usually seen within 2 weeks of administration Varied reactions and lesions including crust and scale Neoplasia Epitheliotrophic lymphoma History – older dog, scaly disease, very pruritic Clinical examination- Nodular, ulceration, chronic disease Diagnostic tests FNA/impression smears – lymphocytes seen Biopsies – quick diagnosis Referral? Treatment Chemotherapy and steroids (milder form- good recovery) Prognosis – poor if severe Source – Veterinarni Medicina, 54, 2009 (8): 387–392 The question answer Summary Scaling and crusting are common clinical signs in small animals Numerous causes Differential diagnostic list and confirming the diagnosis Through work up of the case with a sound clinical reasoning Use clinical reasoning with careful examination of the patient Identifying specific type and distribution of lesions recognizing primary and secondary skin lesions Keep in mind that there can be systemic causes for the lesion not just a local disease References Jackson., H, Marsella., R., (2012). BSAVA Manual of Canine and Feline Dermatology, 3rd Edition., Wiley: ISBN: 978-1-905-31927-5 Kumari KN, Reddy CBK, Kumar MY. (2016) A Case Of Erythema Multiforme Minor In A Dog.;5(6):3856-3859. Maddison., J. M., Volk h. A., Church d. B., (2015) Clinical Reasoning in Small Animal Practice.; Wiley-Blackwell; ISBN: 978-1-118-74175-7 Miller, W. H., Muller, G. H., Scott, D. W., Griffin, C. E., & Campbell, K. L. (2013). Muller and Kirk's Small Animal Dermatology. St. Louis, Mo: Saunders.  Part 2 - Approach to environmental and endocrine dermatosis Dynatra Subasinghe BVSc, PG Dip., MSc, PhD, MRCVS, SFHEA Thursday, 31 August 2023 26 Approach to Environmental and Endocrine Dermatosis Learning Outcomes ✓ Define environmental and endocrine dermatosis ✓ Identify and recognise the common conditions causing environmental and endocrine dermatosis ✓ Describe the various diagnostic procedures to determine aetiology ✓ Discuss approach to appropriate management and treatment of these diseases ✓ Discuss appropriate prognosis, and the welfare implications of management and treatment options chosen ✓ Discuss control measures appropriate for disease prevention where applicable Thursday, 31 August 2023 27 Approach to Environmental Dermatosis Conditions Solar dermatitis Photosensitization Tick infestation Myiasis Foreign bodies Contact dermatitis Burns Frostbite Snake bite Bee stings and spider bites Callus formation Intertrigo (discussed previously) add to list …. 28 Thursday, 31 August 2023 Approach to Environmental Dermatosis Solar dermatitis - chronic sun damage to the skin due to UV radiation Photosensitization - occurs when skin becomes more susceptible to ultraviolet light because of the presence of photodynamic agents - Poorly pigmented nasal skin in dogs - Sunny climate Solar dermatitis Thursday, 31 August 2023 29 Image source – Muller and Kirk, 2013 Tick infestation and Myiasis Warmer climate – ticks recognised more better awareness Spread important diseases Pet travel scheme? Consider prophylactic treatment - Common in rabbits - Often sick animals - Prevent with good husbandry and regular care and attention Thursday, 31 August 2023 30 Source - www.arrownj.com Foreign bodies Very common in dogs – leads to pododermatitis and in ears of dogs Grass seeds can go into ear or into foot and can migrate Surgical inspection and flushing required Thursday, 31 August 2023 31 Image source – Muller and Kirk, 2013, www.vassevets.com.au Contact dermatitis Environmental allergens Plants Gardening supplies and chemicals Plastics, rubber, concrete, or metal Abrasive surfaces Soaps or shampoo Household cleaners etc.. Thursday, 31 August 2023 32 Image source – Muller and Kirk, 2013 Environmental Dermatosis Burns Common – thermal or chemical Diagnosis Usually history, lesion location is suggestive Thorough physical examination is important Frost bite Diagnosis Usually history, lesion location is suggestive. Thorough physical examination is important Thursday, 31 August 2023 33 Image source – Muller and Kirk, 2013 Intertrigo Skin fold dermatitis Bull dogs and Shar-pei Ideal environment for bacterial or Malassezia overgrowth Thursday, 31 August 2023 34 Image source – Muller and Kirk, 2013, www. en.wikipedia.org Approach to Endocrine Dermatosis Hypothyroidism Hyperadrenocorticism Alopecia – X – unknown alopecia Add to the list ….. Thursday, 31 August 2023 35 Hypothyroidism Over/under diagnosed ? Good to keep in mind middle-aged dogs medium to large breed dogs Cat- not common usually due to over treatment of hyperthyroidism – not discussed in lecture Thursday, 31 August 2023 36 Source – www.petactive.wordpress.com Hypothyroidism Aetiology (Dog) Lymphocytic thyroiditis – immune mediated disease – lymphocytes - leading to atrophy- 50% of cases Thyroid neoplasia Congenital hypothyroidism Familial inheritance demonstrated in Borzois, Great Danes and Beagles Secondary due to pituitary neoplasia Thursday, 31 August 2023 37 Source – www. thyroidadvisor.com Hypothyroidism Keep an open mind – look at all signs - holistic Signalment -Large breed dogs- Retrievers, Doberman, boxer, Great Dane, Irish setter Clinical presentation Lethargy, mental dullness, bradycardia, weight gain, hypothermia Myxoedema- droopy appearance Otitis externa Reduced fertility Neurological – laryngeal paralysis, mega oesophagus Skin lesions Thursday, 31 August 2023 38 Source - www.zooland.ro.com, www.petactive.wordpress.com Hypothyroidism Clinical presentation – skin Skin – Bilateral symmetrical alopecia Tail alopecia Hair coat dull Thursday, 31 August 2023 39 Source - www.zooland.ro.com, www.petactive.wordpress.com Hypothyroidism Clinical presentation – skin Skin – cd.. Recurrent pyoderma Can you think of other diseases with similar skin lesions? Thursday, 31 August 2023 40 Source - www.zooland.ro.com, www.petactive.wordpress.com Hypothyroidism Laboratory Tests Hyper cholesterolaemia Normochromic, Non – regenerative anaemia Mild increase in ALT, AST, AP and CK Thyroid function test - diagnosis - total T4 –low - do not rely totally - free T4 - TSH - Autoantibodies – antibodies for thyroid tissue Refer – endocrine disease Thursday, 31 August 2023 41 Hypothyroidism Tests- complex process Total thyroxine (T4) is a very sensitive screening test for hypothyroidism - but a result in the reference range – doesn't give a diagnosis Greatest specificity for diagnosis - Low Total T4 and free T4 with high endogenous TSH But not exclusively diagnostic – dogs with other diseases show this as well Thursday, 31 August 2023 42 Hypothyroidism Tests- complex process Other causes for low Total T4 Sight hounds - low Sick euthyroid syndrome – unwell Cushing's disease- high steroids – low thyroid Drug – side effects– Glucocorticoid NSAIDs If referral case Potentiated sulphonamides or chronic case Anticonvulsants Thursday, 31 August 2023 43 Hypothyroidism Tests Thyroglobulin autoantibodies Evidence of an active inflammatory process in the thyroid gland May not necessarily correlate to actual level of thyroid function Must interpret with other parameters in the panel of assays and clinical signs Thursday, 31 August 2023 44 Hypothyroidism Diagnosis – summary Clinical diagnosis Based on a combination of the following Compatible signalment Clinical signs Physical examination findings Clinico-pathological abnormalities All above supported by specific endocrine testing Thursday, 31 August 2023 45 Hypothyroidism Treatment Levothyroxine 20-40 µg/kg daily in divided doses (10 µg/kg -12 hourly) Dose same time every day- presence of food affects availability Therapy for a minimum of 3 months Trial therapy if acceptable Improvement - mental alertness first, skin last Pre and post-pill T4 testing if possible with TSH testing important When final dose determined – T4 testing every 6-12 months long-life monitoring - required - dosage adjustments may be necessary. Thursday, 31 August 2023 Refer data sheets 46 Approach to Endocrine Dermatosis Hyperadrenocorticism Common endocrinopathy in dogs Quite common in dogs presented in opinion practice Rare in cats Thursday, 31 August 2023 47 Hyperadrenocorticism (revision from year 1) Anatomy and physiology -HPA axis Pituitary dependent HAC – 80- 85% of cases Excessive ACTH secretion leads to adrenal hyperplasia and excess cortisol Failure in feedback mechanism 90% pituitary tumours are benign but may grow over time – suddenly dog gets worse- poor prognosis Most microadenomas Adrenal dependent HAC- 15-20% Usually unilateral adrenal tumours Benign or malignant Often calcified skin- calcinosis cutis Metastatic Image courtesy of wikepedia Thursday, 31 August 2023 48 Slide modified from- SF6 –PBL sessions Hyperadrenocorticism The evidence and Signalment Pituitary dependent hyperadrenocorticism (PDH) A disease of middle-aged to older dogs median 7-9 years 80- 85% of all dogs affected by this disease Small dogs Pituitary adenoma Adrenal dependent hyperadrenocorticism (ADH) - older dogs 15-20% of all dogs affected by this disease Spot the Large dogs pattern Adrenal adenomas or carcinomas recognition One gland enlarged and the other atrophied Breeds- Poodles, dachshunds and small terriers Gender- 60-65% cases female Thursday, 31 August 2023 49 Image source – Muller and Kirk, 2013, content modified form SF6 PBL sessions Hyperadrenocorticism (revision from year 1) Clinical signs Polyphagia and weight gain Abdominal distension – pot bellied – weakening of muscles Muscle wasting/weakness Myotonia Testicular atrophy Anoestrous Neurological symptoms PU/PD can be a diabetic sign in cats Thursday, 31 August 2023 50 Image edited form SF6 PBL session slide Hyperadrenocorticism Dermatological signs Hair Alopecia in dogs or hirsutism in horses (long hair) Hair coat dull Rat tail Skin Hyper pigmented or not Thin and inelastic skin with prominent blood vessels Thursday, 31 August 2023 51 Hyperadrenocorticism Dermatological signs Skin Comedones on abdomen Scale Pyoderma - more prone Comedones Wound healing slow or easily tears Adult onset pedal demodecosis Thursday, 31 August 2023 52 Hyperadrenocorticism Dermatological signs Skin Calcinosis cutis Thursday, 31 August 2023 53 Hyperadrenocorticism Diagnostic approach - Clinical pathology Stress leucogram – lymphopaenia PD – measured and eosinopaenia Urine specific gravity - low less than 1.015 and can be AP increase hyposthenuric 1.008 ALT increase Central Diabetes Insipidus – in severe cases Glucose increase Check for - 50% urinary tract infections Urea and creatinine low 45% dogs have a urine protein:creatinine ratio greater Cholesterol increase -Moderate than 1.0 – prone to kidney disease elevation Total T4 and free T4 reduced – due to steroids Increase in PTH (parathhormone)- not routine. Thursday, 31 August 2023 54 Hyperadrenocorticism Dynamic hormone testing ACTH stimulation test – 2 hours ACTH test for distinguishing spontaneous from iatrogenic Reliable identifies 50% of ADH and about 85% PDH Documents excess production of Glucocorticoids by adrenal cortex Good for monitoring treatment Doesn’t differentiate between ADH and PDH Thursday, 31 August 2023 55 Hyperadrenocorticism Dynamic hormone testing ACTH test –ve but you are not sure Low dose dexamethasone suppression test – 8 hour test- hospitalised time – cost!! Results diagnostic in majority of ADH and 90% with PDH False positives more likely Not for monitoring Not differentiate ADH vs PDH High dose dexamethasone suppression test – used to do – 10 times the low dose Differentiate between PDH (not supressed) and ADH (suppressed) Cats – very high dose needed- uncommon Not used commonly Other tests - urine cortisol:creatinine ratio – not in the scope of this lecture Thursday, 31 August 2023 56 Hyperadrenocorticism Many more tests - Diagnostic imaging Radiography (first opinion) Abdominal ultrasonography (referral) CT/MRI (referral) Thursday, 31 August 2023 57 Hyperadrenocorticism Approach – special notes Suspect an underlying primary disease for dermatological lesions Primary disease maybe hormonal or other Differential diagnosis 1. Hyper adrenocorticism 2. Diabetes mellitus Clinical 3. Liver disease reasoning 4. Hypothyroidism Cannot differentiate sorely on endocrine tests Holistic view – everything must be considered History, signalment, clinical signs, imaging results, dermatological tests, histopathology, and response to treatment etc. Thursday, 31 August 2023 58 Hyperadrenocorticism Treatment and management Treatment is not without risks Client communication very important – animal welfare, their wishes for the animal etc. Options Trilostane – PDH Pituitary irradiation Surgery - Hypophysectomy – referral - remove benign adrenal growth - adrenalectomy Malignant tumours may spread and may not be treatable – poor prognosis Management - lifelong treatment / multiple vet visits / monitoring tests Costly !!! Thursday, 31 August 2023 59 Hyperadrenocorticism Treatment Trilostane - Synthetic steroid - 2-5 mg/kg per day- everyday – divided dose better PDH - 67-90% effective MOA - Competitive, reversible inhibitor of 3 Beta hydroxysteroid dehydrogenase enzyme system which blocks adrenal synthesis of glucocorticoids, mineralocorticoids and sex hormones Monitor with ACTH stimulation test 40-120nmol/l For ADH – use higher dose Side effects Failure to respond Adrenal necrosis Hypoadrenocorticism Hyperkalaemia Vomiting and diarrhoea Thursday, 31 August 2023 60 Approach to Endocrine Dermatosis Alopecia X Old disease names Pseudocushing’s Adult onset growth hormone deficiency Growth hormone responsive alopecia Castration responsive alopecia Adrenal sex hormone imbalance Post clipping alopecia Not much understood 80’s growth hormone responsive 90’s imbalance of adrenal steroid intermediates and sex hormones due to a deficiency in 21 hydroxylase enzyme Thursday, 31 August 2023 61 Alopecia X Signalment and clinical signs Breeds - Nordic breeds with plush coat Pomeranian Chow Keeshond Samoyed Malamute Husky Clinical signs Symmetrical, non-inflammatory alopecia Loss of primary hairs first – down hair Then secondary hairs Hyperpigmentation Treatment Castration (deslorelin®)/ leave it / oral melatonin Thursday, 31 August 2023 62 Approach to Endocrine Dermatosis Seasonal flank alopecia Signalment - Breeds- Airedales, Boxers, Bulldogs Thursday, 31 August 2023 63 References Jackson., H, Marsella., R., (2012). BSAVA Manual of Canine and Feline Dermatology, 3rd Edition., Wiley: ISBN: 978-1-905-31927-5 Miller, W. H., Muller, G. H., Scott, D. W., Griffin, C. E., & Campbell, K. L. (2013). Muller and Kirk's Small Animal Dermatology. St. Louis, Mo: Saunders. Maddison., J. M., Volk h. A., Church d. B., (2015) Clinical Reasoning in Small Animal Practice.; Wiley-Blackwell; ISBN: 978-1-118-74175-7 Thursday, 31 August 2023 64  Thank you Thursday, 31 August 2023 65