Pemphigus foliaceus in feline patients

Most of us do not see pemphigus foliaceus on a daily basis in our feline patients, but we need to know about it; this disease is a challenge in terms of its diagnosis and treatment, and relapse is not uncommon, as the authors explain.

Pemphigus foliaceus (PF) is an autoimmune, vesicobullous to pustular skin disease recognized in many species, most notably dogs, cats, horses and humans. Clinical lesions in small animals typically include pustules and crusts, erosions and ulcers, as well as alopecia (Figure 1) (Figure 2a)(Figure 2b) ( 1 ). The disease is characterized histologically by acantholysis (the breakdown of desmosomes) and loss of adhesion between keratinocytes ( 2 ).
 

The first report of seven cases of feline PF was published in 1982 ( 3 ) and to the best of the authors’ knowledge only two papers of a larger case series (>10 cats) have been published since then ( 4 ) ( 5 ). Five forms of pemphigus are recognized in dogs and cats: pemphigus foliaceus, pemphigus erythematosus, panepidermal pustular pemphigus, pemphigus vulgaris and paraneoplastic pemphigus ( 1 ) ( 6 ) ( 7 ). In contrast to humans, who are frequently affected with pemphigus vulgaris (a deep form of pemphigus), PF is the most common form in dogs and cats ( 1 ).

Many cases of PF need long-term medical treatment with immunosuppressive drugs. While glucocorticoids are often used in feline patients, only limited and contradictory data for the need for, and choice and efficacy of, alternative medications are available ( 1 ) ( 8 ) ( 9 ).

Incidence, prevalence and predispositions

In most cases, the underlying cause for PF cannot be identified ( 1 ). The production of autoantibodies against adhesion molecules may result from an abnormal antigen stimulation or an exaggerated immune response ( 1 ). While genetic predispositions in humans and dogs exist, no such data has been published in cats. Breed and sex predispositions for feline PF have not been reported but domestic short-haired cats are said to be most commonly affected, and the age at disease onset, although reported to have a median of 5 years, can be highly variable ( 4 ) ( 5 ). One study calculated a prevalence of 0.5% for feline PF over a 10-year period, so the disease seems to be rare in cats ( 4 ). [...]