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Table 2 Key dermatologic features for canine pruritic skin diseases

From: Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification

Alesional Pruritus

May be seen in the early stages of allergy or when seasonal disease begins. This finding of pruritus in areas with no lesions can occur in canine AD cases at any point in the disease process, especially in cases that have recurrences or come out of remission.

Primary skin lesions


Can be seen with most of the above differentials, but lice and Cheyletiella do not usually cause erythema. Demodicosis is highly variable – the skin may or may not appear to be inflamed.


Seen with flea bites, scabies, Trombiculiasis, insect bite hypersensitivity, staphylococcal pyoderma, atopic dermatitis, cutaneous adverse food reaction, and contact dermatitis. Dogs with AD may have small non-crusted papules unless there are concurrent diseases.


Most commonly associated with staphylococcal pyoderma

Secondary skin lesions

Epidermal collarettes

Most commonly associated with staphylococcal pyoderma


Most commonly associated with secondary infections and excoriations

Salivary staining

Indicates excessive licking and often associated with Malassezia


Self-induced trauma from scratching due to severe pruritus


May be due to self-trauma or folliculitis (superficial pyoderma, demodicosis, and dermatophytosis)


Indicates chronic pruritus, inflammation and commonly associated with secondary infections


Indicates chronic pruritus. Allergies and Malassezia are the most common causes and result dark discoloration of the skin. Blue-grey pigmentation is seen with demodicosis in some cases.