Equine Pathology Workbook

within peripheral nerves to other, highly innervated areas of the body. One such area is the salivary glands, which are highly innervated by multiple branches of the autonomic nervous system. Virus travels through these autonomic nerves to infect the tissue of the salivary glands, which causes virus to be shed into the saliva when it is secreted. In this way saliva becomes a highly potent vector of transmission for the rabies virus. The incubation period seen with rabies infection is variable, depending on the location of the bite. It can take anywhere from two weeks to two months for the virus to reach the CNS and to cause neurological symptoms. There are 3 different presentations of rabies; aggressive, dumb & paralytic. Clinically rabies infection first presents with general signs of infection including fever, depression, lethargy, and anorexia. Paresthesia may develop at the site of the bite and the horse can be seen itching, licking or tearing at the bite area with it is teeth. Paresthesia may spread or increase as the infection spreads causing the animal to . As the infection leaves the CNS through the efferent nerves signs such as excessive salivation, drooling, pharyngeal paralysis, colic and bruxism develop, followed by CNS signs; ataxia, hyperesthesia, photophobia, muscle tremors, sweating, head tilt, circling, frantic running, seizures, recumbency, coma and death.

Diagnosis is made

through necropsy of the brainstem to isolate viral

proteins and antibodies.

There is no treatment for rabies in animals. Individuals suspected of having rabies are quarantined for a minimum of three months and any animals showing signs or symptoms of rabies and who have an incomplete rabies vaccination record are euthanized. If horse has rabies vaccine, give a rabies booster, isolate and observe carefully. Rabies is preventable through annual vaccination. This is necessary for all animals and is especially important for those individuals that have contact with wild animals. Through vaccination rabies has widely eliminated from the domestic animal and livestock populations in many areas, though occasional cases of infection in wild animals are still reported. In many jurisdictions annual rabies vaccination is mandatory in domestic animals.

Rabies is considered a

disease.

Tetanus

Tetanus is caused by the exotoxin

, which is produced by the anaerobic,

gram positive bacteria Clostridium tetani .

Tetanus bacteria are commonly found in the intestines and the feces of horses and other animals and are found in . Tetanus bacteria are usually introduced into the body through a deep puncture wound caused by an object infected with tetanus spores or live tetanus bacteria.

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