Atopic dermatitisan inherited tendency to allergy to mites, pollen and moulds, the most common cause of chronic itching in dogs.
Flea allergy dermatitisa reaction to flea saliva; a single bite is enough to cause weeks of itching.
Purulent skin infection (pyoderma)a secondary bacterial infection that almost always has an underlying primary cause.
Yeast dermatitis (Malassezia)greasy, smelly, darkening skin in the skin folds and on the paws.
Demodicosis and sarcoptic mangeskin parasites detected in skin scrapings, requiring targeted treatment.
Ringworm (dermatophytosis)contagious to people as well, common in cats and young animals.
Hormonal diseaseshypothyroidism, Cushing's syndrome; the skin is sometimes the first place where they show.
Demodicosisovergrowth of Demodex, a mite that lives in the hair follicles; detected in deep skin scrapings and a trichogram.
Sarcoptic mangea contagious parasite that causes intense itching; it can be hard to find, and a negative scraping does not rule it out.
Purulent skin infectionbacteria on cytology from pustules and under crusts, together with inflammatory cells.
Malassezia dermatitis and otitischaracteristic yeasts on tape cytology or an ear swab.
Ringworm (Microsporum, Trichophyton)confirmed by culture; contagious to people and other animals.
