Halicephalobus gingivalis (H. deletrix) infection in two horses in southern California.

The research article discusses two cases of horses in southern California that were diagnosed with an infection caused by the nematode Halicephalobus gingivalis, demonstrating various symptoms such as renal dysfunction, blindness, and in severe cases, seizures. The paper also notes the detection of the infectious agent in the urine and semen of the horses.

Subject of Study

• The research is focused on two cases of horses in Southern California that were diagnosed with an infection named halicephalobiasis. The causative agent for this infection is the nematode Halicephalobus gingivalis.

Progression of the Disease

• One of the horses, a 16-year-old Holsteiner, developed symptoms of renal dysfunction, eye spasms (blepharospasm), and blindness in the right eye over a period of 4 weeks. The horse also developed a mass in its right kidney. The condition became severe and the horse had to be euthanized after it started having seizures.
• The other case was of a 5-year-old male miniature horse that displayed symptoms such as testicular enlargement and uveitis for a duration of 6 weeks. The horse also developed ataxia (loss of control of body movements) and was later found dead.

Necropsy Findings

• On necropsy examination, there were noticeable bilateral enlargements of the kidneys in both horses. The researchers also found petechial hemorrhages of the optic nerve in the Holsteiner horse and a diffusely firm and enlarged left testicle in the miniature horse.

Microscopic Evaluation

• Upon microscopic evaluation of the tissues, the researchers uncovered granulomatous nephritis, optic neuritis, retinitis, and encephalitis in both horses. The smaller horse was also found to have orchitis (inflammation of one or both testicles).

Detection of the Infectious Agent

• The investigators found evidence of Halicephalobus gingivalis, the disease-causing nematode, in the urine sediment of both horses. The Holsteiner horse also had this nematode present in its semen.