Nodular granulomatous posthitis caused by Halicephalobus (syn. Micronema) sp. in a horse.

The research talks about a rare case of a nodular granulomatous posthitis in a horse caused by the Halicephalobus infection, which leads to inflammation in the central nervous system and commonly affects the brain, kidneys, oral and nasal cavities, lymph nodes, and more. In this study, a 5-year-old male Arabian horse was observed to have multiple nodules on the prepuce’s external lamina, which was diagnosed as cutaneous halicephalobiasis.

About Halicephalobus Infection

• The Halicephalobus infection is a worldwide phenomenon, found in various parts of the globe. This includes the United States, United Kingdom, Japan, Egypt, Switzerland, The Netherlands, and Colombia.
• This infection causes inflammation of the central nervous system. In human beings, it is seen to consistently have an impact on the nervous system and is also seen to have similar effects in equine infections.
• When horses are infected with Halicephalobus, the brain is the most commonly affected tissue. The infection also affects the kidneys, oral and nasal cavities, lymph nodes, spinal cord, and adrenal glands, among others. There have also been cases reported where the heart, liver, stomach, ganglion, and bones have been involved.
• Granulomatous osteoarthritis can also be induced by Halicephalobus deletrix, a species of this genus.

The Case Study

• In the case study conducted in 1990, a 5-year-old male Arabian horse was examined due to multiple nodules on the external lamina of the prepuce.
• No previous trauma was observed by the owner, and other horses in the stable were unaffected.
• Nodule diameters ranged from 0.5-1 cm, and the skin appeared ulcerated over the surfaces. No other clinical signs of infection were evident.
• The horse was diagnosed with cutaneous halicephalobiasis and treated with ivermectin and diethylcarbamazine. The remaining nodules regressed after treatment.
• Examination of a biopsy revealed a thickened dermis with a granulomatous infiltrate, disruption of dermal collagen, presence of multinucleated giant cells, macrophages, eosinophils, neutrophils, and nodular aggregates of lymphocytes and plasma cells.
• The presence of a nematode parasite was found, characterized by an abundance of adults, larvae, and developing eggs.