Rabies is an acute viral infection of the nervous system that affects mainly carnivores and bats, although it can affect any mammal. It is caused by the rabies virus. Once signs appear, it is fatal. Rabies is found throughout the world, although a few countries are declared rabies-free due to successful elimination standards. Islands that have a strict quarantine program in effect are often rabies-free. In North America and Europe, rabies has been mostly eliminated in domestic animals, although it still affects wildlife.
No cat-to-cat rabies transmission has been recorded, and no feline strain of rabies virus is known. However, cats are the most commonly reported rabid domestic animal in the United States. The virus is present in the saliva of rabid cats, and people have developed rabies after being bitten by a rabid cat. Reported cases in domestic cats have outnumbered those in dogs in the United States in every year since 1990.
Transmission is almost always by the bite of an infected animal, when the saliva containing the rabies virus is introduced into the body. The virus can be in the body for weeks or months before signs develop.
Signs and Diagnosis
Most rabid animals show signs of central nervous system disturbance. The most reliable indicators are sudden and severe behavioral changes and unexplained paralysis that worsens over time. Behavioral changes can include sudden loss of appetite, signs of apprehension or nervousness, irritability, and hyperexcitability. The animal may seek solitude, or an otherwise unfriendly animal may become friendly. Uncharacteristic aggressiveness can develop; a normally calm and obedient animal may become vicious. Commonly, wild animals may lose their fear of people. Animals that are normally nocturnal may be seen wandering around during the daytime.
The furious form of rabies is the classic “mad-dog” syndrome, although it is seen in all species. The animal becomes irritable and may viciously and aggressively use its teeth and claws with the slightest provocation. The posture is alert and anxious, with pupils dilated. Noise can invite attack. Such animals lose fear and caution of other animals. Rabid cats can attack suddenly, biting and scratching viciously. As the disease progresses, seizures and lack of muscle coordination are common. Death is caused by progressive paralysis.
The paralytic (or "dumb") form of rabies is usually seen with paralysis of the throat and jaw muscles, often with excess salivation and inability to swallow. Affected animals may also lose muscle control. These animals may not be vicious and rarely attempt to bite. People can be infected by this form when examining the cat’s mouth or giving it medication with bare hands. Again, paralysis progresses throughout the body and death occurs within a few hours.
Diagnosis is difficult, especially in areas where rabies is not common. Early stages of rabies can be easily confused with other diseases or with normal aggressive tendencies. A rabies diagnosis must be verified with laboratory tests. The animal must be euthanized and the remains sent for laboratory analysis.
Control of Rabies
The World Health Organization (WHO) has strict guidelines to control rabies in the dog population. These guidelines (which also apply to cats) include notification of suspected cases, euthanasia of animals with signs of the disease and those bitten by suspected rabid animals, leash laws and quarantine to reduce contact between susceptible animals, immunization programs with continued boosters, stray animal control, and pet registration programs.
Because cats are the most commonly reported rabid domestic animal in the United States, vaccination of cats against the rabies virus is critical.
Management of Suspected Rabies Cases
In areas where rabies is known to exist in the wildlife population (including bats), an animal bitten or otherwise exposed by a wild, carnivorous mammal or a bat that is not available for testing should be regarded as having been exposed to rabies. The National Association of State Public Health Veterinarians recommends that any unvaccinated cat exposed to rabies be euthanized immediately. If the owner is unwilling to do this, the animal must be placed in strict isolation, with no human or animal contact, for 6 months and be vaccinated against rabies 1 month before release. If an exposed animal is currently vaccinated, it should be revaccinated immediately and closely observed for 45 days.
Risk of Passing Rabies to People
When a person is exposed to an animal suspected of rabies, the risk of rabies transmission should be evaluated carefully. Wild carnivores and bats present a considerable risk where the disease is found, regardless of whether or not abnormal behavior has been seen.
Any healthy domestic dog, cat, or ferret, whether vaccinated or not, that bites a person or otherwise deposits saliva into a fresh wound, should be confined for 10 days for observation. If the animal develops signs within those 10 days, it should be promptly euthanized and submitted for testing. If the animal responsible for the exposure is stray or unwanted, it should be euthanized and submitted for testing immediately.
Pre-exposure vaccination is strongly recommended for all people in high-risk groups, such as veterinary staff, animal control officers, rabies and diagnostic laboratory workers, and travelers working in countries where canine rabies is common. However, pre-exposure vaccination alone cannot be relied on in the event of later exposure to rabies virus and must be supplemented by additional doses of vaccine. For healthy, unvaccinated people bitten by a rabid animal, treatment consists of wound care, local injection of rabies antibodies into the wound, and several doses of vaccine over a 2-week period. When provided in a timely and appropriate manner, modern postexposure treatment virtually assures human survival.