ACVD Veterinary Dermatology cheat sheet

Sarcoptes scabiei: superficial epidermal mite; diagnosis by skin scraping (often negative) or pinnal-pedal reflex; responds to selamectin, moxidectin, or isoxazolines.

Demodex canis: follicular mite; generalized disease in dogs warrants evaluation for immunosuppression or endocrinopathy; isoxazoline or moxidectin/imidacloprid are treatment options.

Dermatophytosis: Microsporum canis most common in cats; Wood's lamp fluorescence (apple-green) only detects some M. canis strains; fungal culture is definitive.

Malassezia dermatitis: cytology shows peanut-shaped budding yeasts; treat with topical miconazole/chlorhexidine and address underlying allergy or endocrinopathy.

Canine atopic dermatitis: clinical diagnosis (Pruritus + characteristic distribution); intradermal testing or serum IgE used to select allergen immunotherapy, not to diagnose allergy.

Staphylococcal pyoderma: superficial (bacterial folliculitis, epidermal collarette) vs deep (furunculosis, nodules); methicillin resistance assessed via culture and susceptibility.

Otitis externa: cytology guides therapy - cocci (Staphylococcus), rods (Pseudomonas), and yeast (Malassezia) require different antimicrobial classes.

Hypersensitivity categories: flea allergy dermatitis (caudal dorsum distribution), food allergy (non-seasonal, may affect ears/perineum), and atopic dermatitis (seasonal or non-seasonal).

Ectoparasite treatment: isoxazolines (afoxolaner, fluralaner, sarolaner) target fleas and ticks; macrocyclic lactones target mites; rotate based on efficacy and label.

Dermatology history: age of onset, seasonality, pruritus level, distribution, response to prior therapy, and environment/contact exposures guide differential diagnosis.

Pruritus scale (0-10) helps differentiate primary pruritic disease from secondary infection; a sudden increase in itch often signals infection or flare.

Minimum dermatology database: skin scraping, cytology (tape or impression), fungal culture, and dermatophyte Wood's lamp; add biopsy for deep or refractory lesions.

Glucocorticoid therapy: anti-inflammatory doses suppress pruritus but mask infection; taper and monitor for iatrogenic hyperadrenocorticism.

Antimicrobial stewardship: culture and susceptibility for recurrent or deep pyoderma; limit empirical systemic antibiotics to uncomplicated superficial infections.

Topical therapy is adjunctive cornerstone: chlorhexidine (bacteria/yeast), miconazole (yeast), and ceramides/essential fatty acids for barrier support.

Allergen immunotherapy: 12-18 month trial; response rate ~60-70% in atopic dogs; monitor for adverse reactions.

Zoonotic risk: dermatophytosis, scabies, and Cheyletiella are transmissible to humans; counsel owners on hygiene and environmental decontamination.