Tierdermatologie Deisenhofen Consultations
Clinical clues for pruritus:
Pruritus is frequently used interchangeably with "itch". If it itches, then scratch itů. However "itch" is not just scratching. In dogs, cats and horses, pruritus can cause the following behaviour: rubbing (with front and back paws / hooves) at the nose and eyes, rubbing the sides of the face along the furniture or ground or grass, scratching at the ears with the hind paws/hooves, rolling on the back, licking and biting of the dorsal / ventral paws, claws and/or clawbeds, biting or licking at the flanks, ventrum (especially cats), tugging at the hairs individually (trichotillomania is seen in cats), nibbling or "cobcorning" or licking at the forelegs (antebracheal area), rubbing the tail base on furniture, fences, ground (also referred to as "scooting"), biting and licking at the perianal skin, some special additional behaviors include: dragging of the belly / ventral abdomen over the floor (especially in some breeds of dogs such as pugs, bull terriers), head shaking (in horses).
Cause of pruritus:
Determining the exact cause of pruritus is one of the more difficult challenges in veterinary dermatology. A careful clinical examination is essential to help formulate the differential diagnosis list and microscopy is frequently required to help work through this. Unfortunately allergies are not the only cause of pruritus, infections as well as ectoparasite infestations may occur alone or concurrent to allergies.
Clinical examination and differential diagnoses list:
Pruritus without lesions and without a cytologically evident superficial infection should suggest atopic dermatitis or scabies incognito as the two major differential diagnoses.
Pruritus with lesions may result from self trauma and/or from secondary infection / ectoparasite infestation. Lesions need to be carefully examined for clues such as folliculitis (seen with demodicosis, dermatophytosis and staphylococcal infections), papules and pustules (seen with insect bites, staphylococcal infections and uncommonly with pemphigus). The distribution of both the pruritus and the lesions must also be carefully assessed. For example, involvement of the caudal half of the dog or cat suggests a flea bite hypersensitivity, of the pinnae, elbows and hocks suggests scabies, of the sparsely-haired areas such as axillae and ventrum of either contact allergy or atopy; of the head of atopy, recurrent otitis externa is frequently associated with both hypothyroidism and hyperadrenocorticism and with atopic dermatitis as well as food hypersensitivity.

Labrador with demodicosis
Labrador with atopy