Possible pemphigus foliaceus in a horse.

The research article describes the possibility of a horse affected by pemphigus foliaceus, a type of uncommon skin disease that is normally observed in humans, characterized by shallow erosions, scales, and crusting. The study aims to lay groundwork for understanding the occurrence of this disease in horses.

Research Observation and Clinical Examination

• The horse in question was a three and a half-year-old Thoroughbred cross gelding who displayed symptoms resembling pemphigus foliaceus.
• It had failed to respond to treatment before referral to the University of Sydney Veterinary Hospital and Clinic for investigation.
• Observed symptoms included weight loss, greasy and matted coat, particularly over the neck, severe dermatitis, ventral oedema, and extensive alopecic (bald) areas.

Pathological and Histopathological Findings

• Two punch biopsies revealed hyperplasia of the sebaceous glands, acanthosis of most of the epidermis, diffuse dermal infiltration with mixed inflammatory cells, and the formation of neutrophil-rich crusts.
• Upon autopsy, the horse showed eosinophilic typhlitis with a heavy cyathostomes infection and mild, chronic interstitial nephritis.
• Immunopathological examination for the presence of immunoglobulin using fluorescein labelled protein A did not yield any evidence of immunoglobulin deposits in the skin, suggesting a potential false negative due to conventional histopathological procedures and limitations with formalin-fixed material.

Implications and Conclusion

• The horse’s condition does closely resemble pemphigus foliaceus, however, the lack of immunopathological evidence complicates the diagnosis.
• The researchers caution against premature diagnosis of autoimmune skin diseases without satisfying immunopathological criteria.
• The study suggests that there may be challenges when diagnosing pemphigus foliaceus in horses due to the complex nature of matching clinical, histopathological, and immunopathological factors.
• The article also considers the possibility that the primary disorder in the horse may have been seborrhoea due to the notably greasy nature of the skin and hyperplasia of sebaceous glands.