Equine Rabies
History. Owners report that their horse has not “been itself” for the past few days. Today the animal is extremely lethargic and stands with forelegs wide apart and head held low.
The nostrils are soiled, and the owners report that water and feed come out of the nostrils when the animal attempts to eat or drink.Clinical Examination. From the history and presenting signs, you recognize that the horse may have paralysis of muscles of the pharynx and larynx. Because these lesions are typically associated with rabies in horses, you don a pair of plastic gloves and sleeves and proceed with your examination. To assess the function of the swallow reflex, you attempt to pass a stomach tube. You observe that the swallow reflex appears to be diminished, but that with some persistence the tube can be passed. This indicates that there is no physical obstruction in the pharynx or esophagus and that the problem is functional. These findings support, but do not confirm, a diagnosis of rabies.
Comment. Rabies in herbivorous animals may take a number of forms. One of the most common signs in cattle and horses is paralysis of the pharynx and larynx as a result of viral lesions in the brainstem nuclei supplying the appropriate cranial nerves. If rabies is suspected, no one should come into direct contact with the excretions of the animal, especially saliva.
Treatment. In this horse, treatment should consist of oral fluid and electrolyte therapy administered through an indwelling stomach tube. If there is no response to this conservative therapy, and if the animal's condition appears to deteriorate, euthanasia is necessary, and the animal’s head should be submitted for evaluation for a positive diagnosis of rabies.