Rabies is a severe, invariably fatal viral infection of the nervous system which can affect all warm-blooded animals, including humans. The medical term for the effects of a rabies infection is polioencephalitis.
How Rabies Affects Cats
The clinical signs of rabies can be quite variable, and atypical presentations are often more common than typical ones. The constellation of clinical signs in what is called the "prodromal" or early form of rabies can include attitude and behavioral changes (becoming more solitary, anxious, apprehensive, nervous, shy or aggressive) and other types of erratic behavior (snapping, licking, chewing, biting at a crate or kennel, wandering and roaming aimlessly, becoming excitable and/or irritable).
The paralytic or "dumb" form or phase of rabies – which is less common in cats but more common in dogs - can include lethargy, disorientation, muscular incoordination, excess salivation, impaired ability to swallow, "frothing at the mouth" and changes in the tone of vocalization.
The so-called "furious" form of rabies is seen in the majority of cat cases and the minority of canine cases. It includes aggression, viciousness, biting, paralysis, seizures and hypersensitivity to sound and touch. Most affected cats develop an ascending paralysis preceded by a period of mania and aggression. Some or all of these signs and forms of rabies can (and often do) occur in the same animal.
Causes of Rabies in Cats
The rabies rhabdovirus usually is transmitted in the saliva of an infected animal, typically through a bite or through some entry into disrupted mucous membranes. It is possible but uncommon for the virus to be aerosolized and transmitted upon exposure to large colonies of infected bats. Also rare but possible is transmission through organ transplantation and by ingestion of infected tissues. Regardless of the mode of entry, the virus replicates in muscle cells called "myocytes" and from there spreads into the peripheral and central nervous systems. The virus is susceptible to destruction by vaccine-induced immune mechanisms when replicating in local tissue around the site of infection. However, once it enters the nervous system, it is protected and will replicate rapidly. By this point, infected animals have tremendous loads of virus in their saliva, which reportedly can be shed and infect other mammals up to 2-weeks before the animal shows clinical signs of disease. It can take from 2 weeks to 6 months for clinical signs to appear from the time of the bite or other inciting incident. Unfortunately, once clinical signs are apparent, death almost universally occurs within 10 days.
Preventing Feline Rabies
All cats (and dogs) should be vaccinated against the rabies virus normally after 12 weeks of age, again 12 months later and then every 3 years thereafter (or otherwise in compliance with applicable state regulations). Vaccination protocols are subject to change, so it is important to rely on your veterinarian for the appropriate vaccination schedule for your pet. Cats should be given killed or inactivated vaccines; experts advise against using modified live virus vaccines in cats. The rabies vaccine is very effective and is the best way to prevent this deadly disease in domestic animals. Cats in areas where bats, foxes, skunks or raccoons are present should not be allowed to roam freely.
Rabies is one of the most important zoonotic diseases, because it is so highly contagious and inevitably fatal in pets and people. In the United States, rabies is primarily a disease of wildlife, with the most important strains of rabies found in fox, raccoon, skunk, and bat populations. Each of these strains can be transmitted to domestic cats and dogs, and to humans. Infected raccoons are mainly in the eastern United States. Infected skunks are also found there, as well as in the Midwestern states and in California. Infected bats live in all of the states except Hawaii. Rabid foxes are found primarily in Alaska, Texas, and the Southwest.
Rabies is untreatable and almost always fatal. Animals infected with the virus invariably die within 7 to 10 days after their clinical signs appear. The only way to conclusively diagnose rabies in cats is through post-mortem examination of brain tissue. The current veterinary recommendation is that cats exposed to the virus (i.e., bitten by a known rabid animal) be humanely euthanized. However, again depending on local or state regulations, pet owners may have the option of having their cat securely quarantined in strict isolation for 6 months, so that medical professionals can assess whether clinical signs of rabies develop.
A clinically normal cat that bites or scratches a person should be confined and isolated for at least 10 days (probably under inpatient veterinary care) to see whether it develops any mood change, attitude alteration, or other clinical signs suggestive of rabies. If no signs occur within 10 days of the bite or scratch, then there has been no exposure to the rabies virus.