Revised Pruritus for Veterinary Students - PDF

PRURITUS Allison Foster, DVM, DACVD Western College of Veterinary Medicine 1 Pruritus Itching ▫ Sensation that provokes desire to scratch Most common symptom in dermatology Other factors can exacerbate itch ▫ Anxiety ▫ Boredom ▫ Heat / cold...

PRURITUS Allison Foster, DVM, DACVD Western College of Veterinary Medicine 1 Pruritus Itching ▫ Sensation that provokes desire to scratch Most common symptom in dermatology Other factors can exacerbate itch ▫ Anxiety ▫ Boredom ▫ Heat / cold 2 Pruritus History is important! ▫ Seasonal vs non-seasonal ▫ Distribution of itch ▫ Other animals affected? ▫ People affected? ▫ Length of time affected? ▫ Which treatments have worked? History and physical exam guides differential diagnoses ▫ Diagnostic and treatment plan 3 Visual Analog Scale Pruritus Score to help assess itch level Copyright Thierry Olivry 4 VAScat Vet Derm 2022 ; 33 : 407-413 5 What Causes Pruritus? Allergic dermatitis Parasites Infections Keratinization disorders Neoplasia Autoimmune disease Etc. Allergic dermatitis will be explored today ▫ But remember, other conditions can cause itch! 6 Pathogenesis 7 Pathogenesis – Atopic Dermatitis Defined by The ACVD Task Force on Canine Atopic Dermatitis in 2001 as: “a genetically predisposed inflammatory and pruritic allergic skin disease with characteristic clinical features associated with IgE most commonly directed against environmental allergens.” 8 Pathogenesis Multifactorial disease ▫ Genetic factors ▫ Defective skin barrier function ▫ Abnormal epidermal differentiation ▫ Immunologic aberrations 9 Clinical Presentation 10 Clinical Presentation - Dog Age of onset ▫ 6 months to 3 years Starts seasonal, progresses to non-seasonal ▫ May start as non-seasonal Older dogs ▫ Move from a cold climate to a warm one ▫ Signs develop 1-3 years later 11 Clinical Presentation - Dog Pruritus: ▫ Hairless areas  Axillae, inguinal region, interdigital regions ▫ Other areas  Muzzle, periocular areas, pinnae, flexural surface of the elbow Most common clinical lesion ▫ Erythema 12 Clinical Presentation - Dog Other clinical signs can include: ▫ Conjunctivitis ▫ Otitis ▫ Lichenification ▫ Hyperpigmentation ▫ Acral lick granulomas 13 Clinical Presentation - Dog Pruritus ▫ Leads to self-trauma  Excoriations / Ulcerations  Alopecia Secondary Infections ▫ Pustular dermatitis ▫ Crusting / Scaling ▫ Alopecia 14 Cats! Less is known about allergies in cats Different nomenclature Feline atopic syndrome (FAS) ▫ Allergic dermatitis associated with environmental allergens, food allergy and asthma that may be associated with IgE antibodies 15 Cats! Feline atopic skin syndrome ▫ An inflammatory and pruritic skin syndrome of cats manifested by a spectrum of reaction patterns, none of which are specific for this syndrome, and that may be associated with IgE antibodies to environmental allergens. 16 Feline Atopic Skin Syndrome ▫ Food allergy and flea allergy can both either mimic and/or contribute to this syndrome, and their potential role must be assessed before deciding on the therapeutic approach 17 Clinical Presentation - Cat Young cats appear predisposed ▫ Most show signs between 6-24 months 18 Clinical Presentation - Cat Clinical Signs: Pruritus Alopecia ▫ Face and neck Miliary dermatitis Eosinophilic granuloma complex ▫ Eosinophilic plaque ▫ Rodent ulcer ▫ Eosinophilic granuloma 19 Clinical Presentation - Cat Macules, papules, plaques, excoriations Recurrent otitis Other non-cutaneous clinical signs can include: ▫ Sneezing ▫ Conjunctivitis ▫ Coughing ▫ Asthma 20 Feline Eosinophilic Complex Lesions affecting Diagnosis ▫ Skin ▫ Biopsy ▫ Mucocutaneous junctions Assess for ▫ Oral cavity underlying condition ▫ Allergies  Flea allergy Not a final diagnosis  CAFR ▫ Is a reaction pattern in  Atopic dermatitis cats 21 Feline Eosinophilic Granuloma Three types of lesions are recognized ▫ Feline eosinophilic granuloma ▫ Feline eosinophilic plaque ▫ Indolent ulcer Frequently can occur simultaneously 22 Feline Eosinophilic Granuloma Common ▫ Cutaneous ▫ Mucocutaneous ▫ Oral Im age courtesy of Dr. K inga Go rtel Most likely to be idiopathic Most frequent of the three types Not likely pruritic 23 Feline Eosinophilic Granuloma Usually a linear nodule on caudal thighs ▫ Oral cavity ▫ Lower lip ▫ Chin  Fat chin 24 Feline Eosinophilic Plaque Lesions ▫ Single or multiple ▫ Well circumscribed ▫ Raised ▫ Erythematous ▫ Ulcerated plaques Im age courtesy of Dr. K inga Go rtel Abdomen and medial thighs 25 Feline Eosinophilic Plaque Pruritus is usually severe Secondary infection is common ▫ Some lesions respond solely to antibiotic therapy Identification and treatment of underlying allergy is important 26 Rodent Ulcers Early lesions are crusted, erythematous, depressed ulcers of the lip margin Then enlarge, become well-circumscribed, red- brown Most appear on upper lip Unilateral or bilateral Can progress to squamous cell carcinoma 27 Eosinophilic Granuloma Complex Treatment ▫ Identification of underlying cause  Assess for underlying hypersensitivity disorder ▫ Antibiotics  Amoxicillin clavulanate ▫ Prednisolone / Cyclosporine 28 Diagnosis 29 Diagnosis DIAGNOSIS IS ONE OF EXCLUSION! Based on: ▫ History ▫ Clinical / dermatological signs ▫ Exclusion of other causes of pruritus Diagnosis CANNOT be made with: ▫ Allergy Testing ▫ Biopsy 30 Differential Diagnoses Dog Cat Food Allergy Flea Allergy Secondary Infections Food Allergy Flea Allergy Dermatophytosis Dermatophytosis Parasites Parasites Secondary Infections 31 Treatment 32 Atopic Dermatitis Always remember to address 2º infections!! ▫ Basic work-up includes cytology and skin scrapings ▫ Treat infections!  Infections = pruritus ▫ If you treat with steroids  Stop them before recheck exam! Rule out ectoparasites ▫ Parasite elimination trial? 33 Image Courte sy of Dr. J. Noxon, Iowa State Uni versi ty 34 Secondary Infections Superficial pyoderma ▫ Treat until clinical resolution ▫ Use topical therapies +/- Systemic antibiotics  2-4% Chlorhexidine shampoo  Sprays, Mousse ▫ Recheck exam 35 Malassezia Dermatitis If Malassezia dermatitis is present ▫ Treat with topical therapies  Miconazole / Ketoconazole shampoo  Medicated wipes, Sprays, Mousse ▫ Systemic therapies  Ketoconazole / Fluconazole /Itraconazole  Terbinafine Image Courte sy of Dr. J. Nox on, Iowa State Uni versi ty 36 In Case of Sudden Flares… Ask why? ▫ Exposure to fleas? Other parasites?  Yes, there are fleas in Canada!!!!  All allergic animals should be on flea preventative ▫ If an atopic pet has a sudden flare, have infections been ruled out? 37 Treatment of Atopic Dermatitis Topical Therapies: ▫ Frequent bathing:  Chlorhexidine/Miconazole Shampoos  Hypoallergenic Shampoos Multiple benefits: ▫ Remove allergens from fur ▫ Remove bacteria and yeast 38 Treatment of Atopic Dermatitis Topical Therapies ▫ Wipes ▫ Same theory as Shampoos  Removes allergens  Removes bacteria and yeast ▫ Topical steroids  Skin atrophy  Systemic absorption 39 Treatment of Atopic Dermatitis Systemic Therapies ▫ Antihistamines? ▫ Fatty Acids  Do not use in pets on a food trial ▫ Glucocorticoids ▫ Cyclosporine ▫ Apoquel ▫ Cytopoint What level of itch is acceptable? 40 Glucocorticoids Anti-inflammatory doses If dose is immunosuppressive, question diagnosis Avoid Depo-Medrol if possible 41 Glucocorticoids Steroid sparing effects: ▫ Combine with trimeprazine (Vanectyl-P)  Other antihistamines ▫ Combine with fatty acids Better used as short-term treatment Monitor: ▫ CBC/Chemistry/Urinalysis/Urine Culture q 6 months 42 Glucocorticoids Adverse Effects: Weight gain Urinary tract infections Polyuria Pyoderma Polydipsia Demodicosis Polyphagia Alopecia Behavioral changes Thin skin Panting Calcinosis cutis Diarrhea Cruciate rupture Muscle atrophy 43 Iatrogenic Cushings 44 Calcinosis Cutis 45 Demodicosis Im age courtesy of Dr. Linda Frank, UT 46 Glucocorticoids Steroid side effects Cats ▫ Diabetes mellitus** ▫ Alopecia ▫ Skin atrophy ▫ Curling of pinnae ▫ Congestive heart failure  Use cautiously in cats with known HCM 47 Glucocorticoids Images C ourtesy of Dr. LindaFrank, Univ ersity of Tennesse e 48 Cyclosporine Microemulsified forms are better absorbed (Atopica®) ▫ Be careful with generics ▫ Microemulsified forms still have variable absorption  23-45% bioavailability http:/ /c3.q-ass ets.com/i mages/products/p/y in/y in-029_1z.jpg 49 Cyclosporine Dose: ▫ Dogs 5 mg/kg q 24 hours ▫ Cats 7 mg/kg q 24 hours Can use in conjunction with steroids Can use daily if necessary Can use seasonally ▫ Takes 2-4 weeks before results are seen 50 Cyclosporine Adverse Effects Vomiting, diarrhea Fatal Toxoplasmosis ▫ Cats Gingival overgrowth Other infections Papillomatosis Excessive hair growth Nephropathy 51 Cyclosporine 52 Apoquel (Oclacitinib) Janus Kinase inhibitor Inhibits JAK1 enzyme activity ▫ Pruritogenic and pro-inflammatory cytokines  IL-31  IL-2, IL-4, IL-6, IL-13 Little effect on JAK2 cytokines ▫ Hematopoiesis 53 Apoquel (Oclacitinib) Side effects: ▫ Vomiting, diarrhea ▫ Tumor growth ▫ Demodicosis ▫ Infections (Skin, ear, respiratory) ▫ Bone marrow suppression Off label use with steroids has not been evaluated Do bloodwork! http:/ /www. all iv et.com/p-5263-apoque l-tablet-54-mg.aspx 54 Apoquel (Oclacitinib) Off label use in cats ▫ Not as effective as in dogs ▫ Higher doses 55 Cytopoint (Lokivetmab) Monoclonal antibody Dogs only! ▫ IL-31 ▫ Do not use in cats Injectable Possible side effects ▫ 1-3 days to work ▫ Vomiting ▫ 4-8 week duration ▫ Diarrhea ▫ Allergic reaction ▫ Pyoderma ▫ Otitis externa 56 Cytopoint (Lokivetmab) Safe to use with other Safe to use in all ages medications ▫ Apoquel Neoplasia ▫ Prednisone ▫ Cyclosporine If you have to, ask why… 57 Allergen Specific Immunotherapy (ASIT) 58 Immunotherapy Allergy Testing is not a Diagnostic Test!!! Atopic Dermatitis is a Diagnosis of Exclusion!! Intradermal versus Serology ▫ Neither test is 100% specific or sensitive ▫ Intradermal testing is still performed by most dermatologists 59 Intradermal Allergy Testing Image Courte sy of Dr. J. Noxon, Iowa State Uni versi ty 60 Why Consider Immunotherapy? Biologic approach rather than pharmacologic Modifies the immune responses May prevent progression of disease Reduces or stops repeated use of antibiotics May offer most economical method of control over long term 61 Immunotherapy In general, 4-6 months to see an improvement Can take up to a year Improvement = lifelong therapy Approximately 70% success rate 62 Sublingual Immunotherapy Allergens are administered sublingually Antigen taken up by mucosal dendritic cells Image Courte sy of Dr. J. Noxon, Iowa State Uni versi ty 63 Food Allergy 64 Diagnosis Serum testing is NOT indicated ▫ No correlation between findings and disease ▫ Atopic dogs have higher levels of food IgE ▫ Dogs with primary gastrointestinal disease will have higher levels of food IgG Skin testing does not correlate with clinical disease 65 Which Diet is the Best? Complete history of previous diets Consider cross-reactivity ▫ Beef may cross-react with venison and lamb?? ▫ Chicken, duck and turkey?? ▫ Chicken and fish? http:/ /www. laz erhorse.org/wp-conte nt/uploads/2013/09/She ep-Vs-Cow.j pg 66 Elimination Diet Trial Wean onto new diet Once on the diet, it is exclusive ▫ No treats ▫ No NylaBones ▫ No Bully Sticks ▫ No flavored toothpaste ▫ No flavored medications... 8-12 weeks 67 Which Diet is the Best? Avoid OTC diets!!!!!!! ▫ Can contain common proteins not listed as ingredients Prescription novel protein or hydrolyzed diets ▫ Royal Canin, Purina, Hill’s ▫ Can still have reactions ▫ Food additives may be an allergen source? Home cooked diet trial 68 Confirming the Diagnosis Challenge with the “old diet” If diagnosis is confirmed, then challenge with individual ingredients ▫ Continue elimination diet food while challenging ▫ Introduce new ingredients once every 2 weeks ▫ Symptoms should recur in 7-10 days ▫ Use ingredients from the “old diet” starting with proteins 69 If there is no response to the diet trial and there are no infections, parasites, etc., there is no need to continue the diet! 70 71 Fleabite Hypersensitivity Dogs ▫ No breed or sex  In flea endemic areas  Signs by 5 years Caudal papular dermatitis ▫ Rump ▫ Dorsal thorax ▫ Flank ▫ Tail ▫ Perineal area 72 Fleabite Hypersensitivity Pruritus!!! Corn-cobbing the front legs Acral lick granulomas Pyotraumatic dermatitis ▫ Rump ▫ Side of face 73 Cats No age, breed, sex predilection Pruritus ▫ Face and neck ▫ Dorsal lumbosacral ▫ Generalized Eosinophilic granuloma complex Miliary dermatitis 74 Fleabite Hypersensitivity Management ▫ Flea control for all animals in household! ▫ Environmental control ▫ Anti-pruritic medications Lack of flea infestation does not mean lack of fleabite hypersensitivity ▫ Look for ”flea dirt” 75 In Summary…. Pruritus can be a non-specific clinical presentation ▫ Can be frustrating for owners and clinicians ▫ Affects quality of life for pets and owners Important to consider all possibilities ▫ Don’t just assume a diagnosis of allergies Do skin scrapings and cytology! 76 Thank You 77