Unexplained Neurological Disease Reported in Horses

Horse owners in NSW, Victoria and SA should be aware that there are reports of horses in a number of locations displaying unusual neurological signs. These cases are still under investigation but may result from infection with an arbovirus, most likely mosquito-borne. Cooperation in reporting and investigating similar cases would be appreciated.

Reports indicate the first cases were seen approximately two weeks ago. Initial clinical signs may include depression and mild colic. These are typically followed by the onset of neurological signs including increased responsiveness to touch and sound, facial paralysis with difficulty chewing, stiffness in forelimbs, weakness in hindquarters, and general ataxia (incoordination).

Most animals appear to be recovering slowly, although two cases in Victoria have died  and one horse has been euthanised in NSW.

There has been no evidence of respiratory disease in affected horses, and there is no suggestion that Hendra virus is involved in this syndrome. In NSW, all cases examined to date have been tested for Hendra virus with negative results.

It is vital that appropriate samples and a full history are collected to assist in building a full understanding of this disease.

A range of products are available to protect horses from insect bites and should reduce the risk of horses being infected with an arbovirus by biting insects. They include both physical barriers (e.g., flyveils) and registered chemical treatments.

If your horse is affected with any nervous disorder, contact your veterinarian for an investigation of the disease or the State Department of Primary Industries for more information.