PEMPHIGUS FOLIACEUS IS A RARE autoimmune disease in cats accounting for less than 1% of the author’s skin cases. It is, nevertheless, considered to be the most common autoimmune disease of the skin seen in both dogs and cats.
Autoantibodies attack a component of the adhesion molecules on keratinocytes, leading to lack of intercellular cohesion in the stratum spinosum or subcorneal level of the epidermis (Hnilica and Patterson, 2017; Paterson, 2008).
Clinical signs
- No age, breed or sex predilection. Cases have been seen in cats less than a year of age and in those more than 16 years.
- Crusting lesions are typical, particularly of the nose, face and pinnae (Figure 1).
- Lesions may progress ventrally, often surrounding the nipples. n A frequent and unique feature is a sterile paronychia, which may exhibit a thick caseous discharge (Figure 2).
- Hyperkeratosis of the footpads is sometimes present.
- Fever, anorexia, lymphadenopathy and depression may be observed.
Differential diagnosis
- Bacterial paronychia.
- Dermatophytosis.
- Food allergy.
- Ectoparasitic infestation.
- Food allergy.
- Atopy.
- Facial dermatitis of Persian cats.
Diagnosis
- History and physical examination.
- Cytological examination of primary lesions or nail bed exudate often reveals acanthocytes (detached keratinocytes formed as a result of acantholysis) surrounded by non-degenerate neutrophils (Figure 3).
- Histopathological examination. Sub-corneal pustules containing acanthocytes and non-degenerative neutrophils are diagnostic. In both histopathological and cytological examinations, bacteria are usually absent.
- Bacteria, if detected, are considered secondary to the primary autoimmune disease.
Treatment
- In many cases, cats respond well to glucocorticoids. Of these the first choice is prednisolone (2-2.5mg/kg by mouth q 12-24 hours) (Figures 1 and 4). Prednisolone was very successful as monotherapy in a series of cases (Simpson and Burton, 2013).
- Dexamethasone (0.1-0.2mg/kg by mouth q 12-24 hours) may be used if the case does not respond to prednisolone (Hnilica and Patterson, 2017; Paterson, 2008).
- Successful treatment with cyclosporine has been reported (Irwin and others, 2012).
- Other drugs such as triamcinolone and chlorambucil are also reported to be effective (Hnilica and Patterson, 2017).
A percentage of cats will be cured and require no further treatment. In those that are not cured and treated with glucocorticoids, the aim will be to find the lowest possible dose that maintains remission and give the treatment on alternate days or less.
References
Hnilica, K. A. and Patterson, A. P. Small Animal Dermatology: A Color Atlas and Therapeutic Guide. 4th edition; pp245-257. Elsevier, 2017.
Irwin, K. E. and others (2012) Use of modified ciclosporin in the management of feline pemphigus foliaceus: a retrospective analysis. Veterinary Dermatology 23 (5): 403-476.
Simpson, D. L. and Burton, G. G. (2013) Use of prednisolone as monotherapy in the treatment of feline pemphigus foliaceus: a retrospective study of 37 cats. Veterinary Dermatology 24 (6): 598-e144.
