Onchocerca cervicalis in horses: dermal histopathology

Area of Science:

• Veterinary Dermatology
• Parasitology
• Equine Pathology

Background:

• Onchocerca cervicalis is a common filarial parasite in horses.
• Cutaneous manifestations of onchocerciasis can vary.
• Histopathology is crucial for diagnosing skin conditions in horses.

Purpose of the Study:

• To identify histopathological differences in equine skin associated with Onchocerca cervicalis.
• To investigate potential seasonal variations in parasite burden and inflammatory responses.
• To characterize dermatitis in horses with and without confirmed onchocerciasis.

Main Methods:

• Histopathological examination of ventral midline skin biopsies from horses.
• Comparison of skin lesions between horses with and without Onchocerca cervicalis.
• Assessment for seasonal variations in parasite presence and cellular infiltration.

Main Results:

• Perivascular mononuclear dermatitis was the most consistent histopathological finding differentiating horses with onchocerciasis.
• No significant seasonal variation in parasite numbers or inflammatory cell influx was observed.
• Eosinophilic dermatitis was present in horses affected by onchocerciasis and those with idiopathic dermatitis.

Conclusions:

• Perivascular mononuclear dermatitis is a key histopathological indicator of equine onchocerciasis.
• Equine onchocerciasis may not exhibit distinct seasonal patterns in parasite load or cellular response.
• Eosinophilic dermatitis can occur in both onchocerciasis and other dermatitides of unknown cause in horses.