Animals have a remarkable knack for stealing our hearts, and it doesn’t take long to develop a deep emotional bond with a new pet. This makes it all the more distressing to find out that a seemingly healthy young cat is harboring an incurable and potentially fatal illness. It is unfair but unfortunately common with the feline immunodeficiency virus and feline leukemia virus.
FIV sounds like HIV, which is apt and can give you a decent sense of what the virus does. It is often referred to as feline AIDS, but just as with the human infection, this term only properly applies to the syndrome that occurs in the later stages. Until that happens, infected cats may show little or no evidence of the illness. But their immune systems are generally compromised by the virus, leaving them vulnerable to other infectious diseases and parasites. After a positive diagnosis, cats should receive frequent checkups to detect and treat secondary illnesses.
Cats with FeLV may also have suppressed immunity, but the virus ultimately gets its name from its ability to cause cancer in its victims. The virus replicates by inserting its DNA into the animal’s host cells, and the genetic mutation can cause infected white blood cells to lose control of their own replication, resulting in leukemia or lymphoma.
Both FIV and FeLV require close contact (such as mutual grooming) or biting to transmit, and they’re fragile outside their hosts. (Don’t worry, the viruses are not transferable to humans.) Infected cats should be kept indoors not only to avoid challenging their weakened immune systems, but also to prevent the infection of other cats.
Most veterinary clinics can test for these viruses with a simple in-house kit, but testing often falls by the wayside once cats have tested negative as kittens. This is potentially dangerous, especially in cats demonstrating chronic or recurring illness. False negatives are possible depending on the exact stage of infection, and it is important not to be complacent just because a cat tested negative years ago. While routine testing may not be warranted for healthy indoor cats, it can be valuable for those who are sick or spend a lot of time outdoors, where they might get into a scuffle.
Both viruses have vaccines, but their use is not cut and dried. The FIV vaccine can be wise in certain at-risk patients, but it comes with a big hitch in that it interferes with all common means of testing. Cats that have been vaccinated for FIV will test positive for infection. But since the vaccine is only about 80 percent effective, this makes for potential confusion if a pet develops worrisome symptoms after getting a dose.
It is far easier to recommend the FeLV vaccine for patients with a higher risk. Although the vaccine is also not perfectly effective, it does not interfere with testing, so we don’t lose clarity down the line. It only has an upside.
If you find yourself confronted with either diagnosis, it’s important to take a breath. The news is undeniably unfortunate: Neither virus is curable, and infected cats are likely to require more veterinary care to screen for trouble and to fend off secondary illnesses. But a pet owner should not let concern spiral into despair: Infected cats often experience many years without any symptoms at all, even into old age.
One of the joys of having pets is the perspective they bring. Even when their own health is endangered, they take life one day at a time and remind us to do the same. And in this case, there may well be a lot of good days to come.
Dr. Mike Fietz is a small-animal veterinarian at Georgetown Veterinary Hospital. He received his veterinary degree from Cornell University in 2003, the same year he moved to Charlottesville.