Spongiotic vesicular dermatitis as a cutaneous reaction pattern in seven horses.

This research describes a skin condition observed in seven horses over six years, which presented as oozing, inflamed skin lesions. The researchers investigated the possible causes and symptoms, suggesting it could be related to an immune response or other conditions like hives.

Research Context

• This dermatitis was observed in a variety of horse breeds and genders over a six-year period.
• The skin disease did not seem to be associated with any other systemic illness in the affected horses.

Observed Symptoms

• The condition manifested as multifocal, exudative or oozing skin inflammation, specifically in the form of epidermal vesicles.
• At a cellular level, there was what is described as ‘spongiotic vesicles’ in the epidermal layer of the skin and perivascular inflammation, describing inflammation surrounding the blood vessels.
• Some horses also showed signs of itchiness (pruritus), and two had a history of recurrent urticaria, a condition that causes hives or welts.
• One of the horses initially had nodular or welt-like lesions that developed into the oozing skin condition.

Immunological Investigation

• The researchers used a method called avidin-biotin complex-peroxidase staining to detect presence of Interepithelial immunoglobulin G (IgG), an antibody that usually plays a key role in the body’s immune response.
• The staining pattern suggested the presence of epithelial oedema (swelling in the skin layer), but did not suggest specific IgG deposition typically associated with the skin condition pemphigus. Hence, pemphigus was ruled out as a possible cause for the observed skin condition.

Progression and Possible Cause

• The researchers observed that the oozing lesions developed under specific circumstances where dermal oedema, or swelling in the skin, appears to be progressing to both intracellular and intercellular epidermal oedema.
• Suggestively, this increased swelling then seems to progress to the formation of the spongiotic vesicular lesions.
• The research indicates a progression from dermal to epidermal oedema, leading finally to the spongiotic vesicular epidermal lesions, although more research is likely needed to confirm this pathology.