Cerebrospinal nematodiasis caused by a filariid in a horse.

This research article details a case study of an atypical case of cerebrospinal nematodiasis in a 12-year-old Quarter Horse mare, caused by a filariid nematode. The horse demonstrated various symptoms such as motor weakness, ataxia, and incontinence, ultimately succumbing to the disease.

Introduction to Cerebrospinal Nematodiasis

• Cerebrospinal nematodiasis is a disease in horses characterized by motor weakness and ataxia, which may gradually escalate to total paralysis.
• The typical causative agents are Setaria spp in Asia and Strongylus vulgaris in North America, and in this case, an additional potential causative factor, Hypoderma spp, found in North American horses, is noted.

Case Description and Clinical Observations

• The subject was a 12-year-old Quarter Horse mare that was admitted to a clinic due to hindlimb ataxia that worsened over two days, ultimately leading to the horse needing help to stand.
• Despite her physical difficulties, the mare remained alert and was able to eat and drink when assisted into a certain position. She had signs of urinary incontinence and distended bladder but could defecate normally.
• The mare exhibited several abnormal neurological signs such as lack of patellar and triceps reflexes, crossed-extensor reflex in the hindlimbs, and absence of superficial pain responses in the coronary band of all feet.

Diagnostic Process and Treatment Attempt

• Upon admissions, blood analysis revealed normal results except for high plasma creatinine phosphokinase activity, expected due to the horse’s recumbent state.
• There was an increase in total protein and cellular content, as well as slight xanthochromia in the cerebrospinal fluid (CSF) collected from lumbosacral samples on the third and fifth day of the disease progress.
• Notwithstanding the supportive therapy the mare’s condition declined, leading to her death on the sixth day, marked by fever and elevated heart and respiratory rates.

Postmortem Findings

• A necropsy was performed, revealing congestion in the right lung and kidney, fibrin tags on the liver capsule, and larvae projecting into the lumen of the cranial mesenteric artery.
• The brain and spinal cord revealed no obvious abnormalities on being sectioned and observed.
• A filariid larva, associated with the lesions, was discovered in the cervical spinal cord of the deceased mare, an unexpected finding as this particular type of worm is not typically associated with cerebrospinal nematodiasis in North American Equine.