Rabies in farm animals

A fatal infectious disease of people and other mammals caused by a virus called lyssavirus. Rabies affects the nervous system of warm blooded animals including humans. Rabies is a fatal disease and the primary goal is to prevent infection. The disease has a long incubation period (six months) and symptoms may take several weeks to appear after infection. However, once symptoms appear, rabies is always fatal in animals.

How is rabies transmitted?

Rabies is transmitted through the saliva of an infected animal. Infection occurs primarily via bite wounds, or infected saliva entering an open cut or wound or mucous membrane, such as those in the mouth, nasal cavity or eyes.

The virus will generally remain at the entry site for a period of time before travelling along the nerves to the brain. In the brain, the virus multiplies quickly, resulting in clinical signs. The virus then moves from the brain along nerves to the salivary glands. The period of time before clinical signs appear in an infected animal can vary depending on the strain of virus and entry point. It is thus important to realise that the disease can be transmitted via the saliva of an infected animal to other animals and humans before the onset of clinical signs of the disease in the infected animal. People can also get infected when saliva gets directly into the eyes, nose, mouth or a wound.

What animals are affected by the disease?

It is important to recognize that wild animals, domestic animals Dogs and farm animals cattle, small stock and humans can get infected and transmit the disease.

What are symptoms of rabies?

Symptoms usually develop 10 days to 7 months after exposure, and can result in death 2-12 days later. Behavioral changes and unexplained paralysis are most indicative of rabies. Signs include anorexia, apprehension, nervousness, irritability, hyper-excitability, ataxia, change in voice, uncharacteristic aggressiveness, seeking solitude.

In the furious form the animal becomes very aggressive and vicious

Paralytic or dumb form is associated with profuse salivation and inability to swallow due to muscle paralysis. Wild animals will often display abnormal behaviors and loose fear of people and other animals.

Clinical signs in farm animals (cattle, small stock, dogs)

Clinical signs of rabies can be varied in cattle, smallstock and other animals. Some of the more common clinical signs include:

  • Sudden change in behavior
  • Progressive paralysis
  • Ataxia (the loss of full control of bodily movements)
  • Abrupt ending of lactation in dairy animals (the fact or process of ending or being brought to an end)
  • Hypersensitivity/alertness
  • Abnormal bellowing
  • Paralysis of the throat
  • Drooling
  • Head extension
  • Bloat
  • Choking behavior

Clinical signs in Humans

From the point where the rabies virus entered the body, the virus moves towards the brain along the nerves. A person may show the first signs of rabies an average of one to three months after the virus enters the body. In humans, the first symptoms of the disease are non-specific and resemble other viral infections, they include:

  • pain at the bite site
  • a general feeling of illness
  • fever
  • headache
  • poor appetite, nausea, and vomiting
  • muscle aches
  • sore throat
  • depression

In 4 – 10 days, neurological symptoms will appear as the virus begins to multiply in the spinal cord or brain. These symptoms include:

  • anxiety
  • confusion
  • excessive saliva production
  • hallucinations
  • high level of excitement
  • insomnia (habitual sleeplessness; inability to sleep)
  • paralysis of lower legs
  • problems swallowing due to painful throat and voice box spasms
  • hydrophobia (fear at the sight of water despite an intense thirst)
  • restlessness

Prevention & Control

In countries where the disease is endemic, measures are implemented to address and reduce the risk of infection in susceptible populations (wildlife, stray and domestic animals) and create a buffer between the animal source of the disease and humans.

  • Surveillance and reporting of suspected cases of rabies in animals
  • Vaccination programs for domestic animals
  • Research into disease dynamics, vaccines and effective delivery mechanisms for target populations
  • Wildlife rabies control programs including vaccination (trap/vaccinate/release or delivery of oral vaccines)
  • Population control and vaccination programs for stray animal populations.

Situation in Botswana

There is free compulsory annual vaccination of dogs and cats by government personnel. Dogs and cats which are three months old or above are vaccinated and a certificate of vaccination is issued to the dog or cat owner. Also dogs and cats are marked with paint and immediately after vaccination, a tie-up order is imposed and dogs without paint are shot. Owners wishing to move their dogs and cats from one zone to another are issued with inter zonal permits which should be accompanied by up-to-date rabies vaccination certificates.