Ataxia in four horses with equine infectious anemia.

The study reports on four horses with equine infectious anemia (EIA), detailing ataxia as a predominant symptom, along with other clinical signs and lab findings. It also describes neuropathologic processes, the onset timings of the neurological signs, and the characteristics of cerebrospinal fluid in these horses. Finally, premises are made on the production of anti-EIA antibodies.

Ataxia as a Predominant Symptom in Horses with EIA

• The research observed that in four horses diagnosed with equine infectious anemia, ataxia, or loss of full control of bodily movements, was the primary clinical sign.
• Alongside ataxia, these horses also showed typical symptoms and laboratory results often associated with EIA like weight loss, anemia, fever, lowered platelet count, hemorrhages, excessive quantities of antibodies or other proteins in the blood, and elevated activity in enzymes of the biliary tract.

Neuropathologic Processes in Horses with EIA

• The study showed specific non-suppurative (not producing pus), granulomatous (formation of granulomas: collection of immune cells) inflammation of the lining of the ventricles of the brain and the spinal cord, inflammation of the protective membranes covering the brain and spinal cord, and inflammation of the brain and spinal cord in the horses, hinting at a neuropathologic implication of EIA.
• Moreover, the presence of an excess of specific white blood cells, including plasma cells and lymphocytes, in the brain and spinal cord was observed, indicating an immune response at these sites.

Onset Timings of Neurological Signs and CSF Characteristics

• A noteworthy observation was that the emergence of these neurological symptoms corresponded with the acute phase of infection in at least two horses. However, in one case, these symptoms arose at least 18 months post-infection.
• The study of cerebrospinal fluid (CSF) from three of these horses revealed high concentrations of protein and white cells, suggestive of an inflammatory response. One horse’s CSF changes might have been influenced by a prior traumatic attempt to sample CSF.
• Meanwhile, on comparing the CSF from three EIA-infected ponies showing no apparent symptoms, the CSF was found to be normal.

Suspicion of Active Production of Anti-EIA Antibody

• Finally, serologic findings led to a suspicion that there was an active production of anti-EIA antibody in the CSF, indicating the body’s defensive response to the EIA infection in the nervous system.