Feline Foamy Virus: What Is It and Why Does It Cause Arthritis in FIV Cats?
What Is Feline Foamy Virus (FeFV)?
Feline foamy virus (FeFV) is a retrovirus, just like FIV, that infects cats; oftentimes, without causing any signs of illness. However, some strains of the virus are known to cause lymphocytes, which are white blood cells that defend the body from harmful foreign matter, to burst and therefore, weaken the immune system. With that said, similar to FIV, FeFV may make infected cats more susceptible to diseases and infection.
Additionally, FeFV is generally more common in free-roaming or outdoor cats, but the possibility of a cat contracting the virus also increases with age. This is mainly because, like humans, their immune system becomes weaker as they become older, making it easier for invaders to enter the body.
Why Does FeFV Cause Arthritis in FIV Cats?
While cats with FeFV normally appear healthy and do not show any signs of disease or infection, FIV cats that contract FeFV (or cats with FeFV that contract FIV) usually develop chronic progressive polyarthritis—a rare condition that triggers an immune response that causes arthritis to develop in multiple joints simultaneously.
According to PetMD, cats that contract both viruses often exhibit unsteady gait, sore or swollen joints, and enlarged lymph nodes. However, there is currently no concrete reason as to why this happens.
How Do FIV Cats Get FeFV?
Since FeFV seems to be quite prevalent in a number of cat populations, experts believe that it may be transmitted through casual contact. However, because it is more common in cats that live outdoors or at least have access to it, there’s also a possibility that it spreads through cat bites, like FIV. An infected mother cat may also transmit the virus to her kittens while they’re inside her womb.
How Is an FeFV Infection Diagnosed?
If you suspect that your FIV cat has FeFV, bring them to the vet right away. Once there, your veterinarian will ask you a few questions, including the signs you observed, your cat’s medical history, etc. After that, your cat will undergo a complete physical examination, a series of blood tests, and a urinalysis.
Your veterinarian may also take a sample of your FIV cat’s joint fluid to check for chronic progressive arthritis. In some cases, a blood sample may be needed for serologic testing, which helps detect the presence of FeFV antibodies (proteins produced by the body in response to infection). However, since this test is not readily available and a bit costly, most veterinarians deem it unnecessary.
What Are the Treatment Options for an FeFV Infection?
Unfortunately, just like FIV, there are currently no available treatment options for an FeFV infection. Usually, veterinarians simply prescribe an immunosuppressive medication, such as prednisone, to cats suffering chronic progressive arthritis.
However, since immunosuppressive medication reduces pain and inflammation in affected joints by weakening immune responses, it needs to be administered with extreme caution to cats with FIV or FeLV.
How Can I Prevent My FIV Cat from Contracting FeFV?
To prevent your FIV cat from contracting FIV, it is best that you keep them indoors, away from outdoor cats. That way, you not only remove the risk of your cat picking up the virus but also prevent the spread of FIV to outdoor cats that are already at a higher risk of falling victim to both viruses.
It is also important that you get your cat fixed, if you have not already, to minimize the likelihood of aggression and cat fights, especially if you have multiple cats. If your healthy cats contract FIV, that increases their chances of developing FeFV.
Additionally, make sure that you maintain routine vet visits to keep track of your FIV cat’s health status and spot developing illnesses or infections right away.