Canine dermatitis on contacting grass leaf: A case series

Pruritus is a common clinical sign in dogs for which owners seek veterinary attention. Its diagnosis and treatment are often a source of frustration for the owner and veterinarian. Contact dermatitis is rarely considered, even when lesions are located only on the skin. This report describes the immediate reaction to grass leaf material after skin exposure, with similarities to human protein contact dermatitis.

To describe the history, clinical findings, diagnostic methods, and characteristics of an undescribed canine pruritic dermatitis that is clinically distinct from canine atopic dermatitis and contact dermatitis.

Eighteen pet dogs living in Australia were referred for unresolved pruritic dermatitis.

Retrospective analysis of clinical records from patients with pruritic dermatitis after contacting grass leaves. Findings on skin testing, isolation, challenge, and description of skin lesions are described.

Dogs had an inflammatory and pruritic dermatitis affecting the ventral chest, anterior-medial thighs and distal limb, areas that had been in contact with grass, which dogs instinctively avoided. Erythema and erythematous macules and papules were characteristic in the affected skin, inducing coat loss, and thickened pigmented skin. Isolating the dogs from grass resolved their clinical signs and pruritus returned within hours of contact with causative grass.

A literature review revealed that this canine dermatitis was similar to human protein contact dermatitis. The impact may be enormous for the treatment of dogs having this disease because the treatment path differs from the therapeutic options of common canine pruritic skin disorders, including the possibility of cure by avoidance.