Rabies

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Rabies

Hydrophobia, Lyssavirus

Rabies is a fatal zoonotic disease caused by a type of Lyssavirus or the Rhabdoviridae family that affects all mammals, including horses and humans. Cases of rabies occur worldwide, with the exception of Australia, which has a slightly different but related virus called Australian bat lyssavirus. Due to the availability of a vaccine, rabies in horses is relatively uncommon. However, horses that aren't vaccinated against rabies are sensitive and susceptible to the disease. In addition, there is no effective treatment once a horse is infected. The disease is 100 percent fatal to all infected animals, including humans. Vaccinating the horse prior to exposure is the best form of protection.

Clinical signs
Clinical signs of rabies in horses are diverse and can appear similar to several diseases that affect the horse's nervous system. Clinical signs usually progress quickly, over a course of 4 to 7 days, sometimes less. Horses usually will ultimately die as a result of cardiorespiratory failure.

Transmission
Horses are exposed to the rabies virus through the bite of an infected (rabid) animal, usually from the wild such as a raccoon, skunk, wild dog, fox, opossum, bat, or mongoose. Horses are usually bitten on the muzzle, face, and lower limbs. Once bitten, the virus migrates via nerves to the horse's brain, where it initiates rapidly progressive, invariably fatal encephalitis. Rabies exposure and transmission occur only when the virus is introduced into bite wounds, into open cuts in skin, or onto mucous membranes from saliva or other potentially infectious material such as neural tissue.

Incubation Period
The incubation period for rabies in horses varies from 2-10 weeks depending on what part of the body is bitten. The average incubation period in horses is 12 days.

Symptoms

Behavioral changes
Lethargy
Aggressiveness
Hyperreactivity
Extreme agitation
Depression
Distress
Circling
Ataxia
Head tilt or pressing
Ascending paralysis
Tail weakness
Inability to get up
Bladder incontinence
Convulsions
Teeth grinding
Drawing lips back and forth
Excessive salivation
Pharyngeal paralysis
Abnormal vocalization
Lameness
Erratic drinking
Loss of appetite
Fever

Diagnosis

  • History
  • Clinical signs
  • Necropsy - Hemorrhagic malacia in the spinal cord.
  • Fluorescent antibody test - of the brain

While waiting for your veterinarian

  • Horses suspected of having rabies should be handled with care, and all those in contact with the horse should wear protective gear including eye goggles, face shields/masks, and gloves during interaction with the animal.

Treatment


TreatmentDetails
Report diseaseRabies is a reportable disease, meaning that if you suspect that your horse has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
If horses are exposed to a rabid animal that are currently vaccinatedShould receive immediate revaccination by a licensed veterinarian. The horses will need to be keep on strict observation (as directed by public health officials) for 45 days for development of clinical signs of rabiesAAEP Guidelines
If unvaccinated horses are potentially exposed to a rabid animalHorse owners should contact their public health official immediately as they will have established requirements and conditions for the monitoring and/or disposition of exposed, unvaccinated animals. These officials will dictate what options are available for the exposed horse. (These options may include isolation and immediate post-exposure immunization of the horse). Alternatively, the horse can be euthanatized immediately.AAEP Guidelines

Prevention

  • Ensure that adult horses are vaccinated once a year.

Prognosis

Fatal

Scientific Research References

Good Overviews