Skin disease in dogs and cats is extremely common and new cases are seen at the Fairfield Veterinary centre in significant numbers on a daily basis. Since most of these diseases present in a very similar fashion, (an itchy patient!) it can be a painstaking process to determine an exact cause.

Often a thorough clinical examination will guide us in a specific direction because of the distribution of the lesions or itchy and affected areas. So when Rosie's lesions were noted to be present around her lips and genitals I was concerned about the possibility of an autoimmune disease. Biopsies of the affected areas confirmed this to be the case and Rosie was diagnosed with Pemphigus foliaceus.

Autoimmune diseases are present when a patient's immune system attacks the patient itself. Antibodies usually directed towards harmful micro-organisms start to identify the patient's own proteins as "hazardous".

The target area varies depending on the type of autoimmune disease so that in this instance the affected area is the skin protein desmoglein1.

Once identified as the "enemy", affected cells are liquefied by proteolytic enzymes. This process leads to the formation of blisters, pustules and honey coloured crusts. The exact cause is unknown but is thought to have a significant genetic predisposition due to the high incidence of affected pedigree dogs.

This theory is mirrored in humans where, due to it's high occurrence in Indian populations in central Brazil, it is currently undergoing research.

Besides the evident genetic predisposition, it is thought that additional factors may be involved such as solar radiation, flea saliva and infectious agents. The response to treatment can be very variable and endeavours to suppress the immune system to avoid further damage.

Fortunately, for Rosie she is making excellent progress and those rather painful patches are healing extremely well. As far as I am aware the closest Rosie has ever been to Brazil is watching the football team on the television!

Terry Dunne BVMS, Cert SAO, MRCVS

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