Feline Foamy Virus Infection in Cats

Although FeFV is not thought to present a major threat, cats infected with the virus are often also infected with feline immunodeficiency virus (FIV). FIV is known to cause symptoms. If you suspect your cat may be infected with FeFV, either because they have come into contact with another infected cat or they exhibit symptoms of FIV, it is important to schedule an appointment with a veterinarian.

Feline foamy virus (FeFV) is a retrovirus that affects cats. Generally, FeFV is not pathogenic, meaning it is not thought to cause harm or elicit symptoms from infected cats. While the mode of transmission of FeFV is not completely understood, the virus can be spread from one cat to another.

Cats infected with FeFV are generally free of symptoms. While studies show cats infected with FeFV do not present with any clinical symptoms, changes in tissue of the lungs and kidneys have been observed over time. The jury is still out on whether FeFV may cause symptoms or adverse effects down the road. Some long-term complications of FeFV infection include:

• Progressive polyarthritis
• Enhancement of FIV
• Chronic kidney disease

Cats with FeFV are often co-infected with FIV. If your cat comes into contact with a cat confirmed to carry FeFV, it is important to schedule an appointment with a veterinary professional as soon as possible, especially if she exhibits any of the following FIV symptoms:

• Acute illness, such as vomiting, diarrhea, kidney disease or pneumonia
• Gingivitis
• Chronic infections, such as urinary and respiratory tract infections
• Poor coat condition
• Slow weight loss
• Spontaneous abortion of kittens
• Behavior changes
• Seizures

Veterinary professionals hypothesize FeFV has two major modes of transmission, both thought to be mediated by saliva. These two routes of FeFV transmission are:

• Aggressive behavior: Aggressive behavior, such as fighting that involves biting and scratching, is thought to be the primary mode of transmission of FeFV.
• Intimate contact: Intimate contact between two cats, as with domestic cohabitation, is another theorized mode of FeFV transmission. This accounts for the higher proportion of older cats infected with FeFV.

It should be noted that the above hypotheses about FeFV in cats are still in the theoretical stages, though research is currently being performed to better understand this virus, its symptoms and its repercussions. If your cat has come into close contact with a cat infected with FeFV or exhibits symptoms of FIV, contact a veterinarian right away for confirmation of infection. 

A veterinarian may begin examination of a cat thought to have feline foamy virus with a medical and social history. He or she may ask questions to determine whether your cat has been in close contact with other cats. Routine blood and urine samples will be collected for a biochemical profile and complete blood count to confirm FeFV infection, test for FIV, or perform testing for differential diagnoses. 

FeFV in cats is confirmed using a serum antibody test. A cat infected with FeFV will test positive for antibodies specific to the virus. This test, while relatively safe, is expensive and rarely performed outside of an experimental setting. If your cat is asymptomatic, it is unlikely a veterinarian will perform additional tests to confirm infection. If your cat is exhibiting the signs and symptoms of FIV, a veterinarian will likely test for those viral antibodies instead, as the test is more common and less expensive. 

There is no treatment for cats infected with FeFV. In fact, if continued research shows the virus manifests no symptoms of its own, the virus might play a role in the treatment of other pathogenic cat viruses, such as FIV. 

This conservative approach to treating FeFV is regarded as safe. The only complicating factor is the possible onset of progressive polyarthritis, which may be treated in a number of ways. Cats with arthritis in multiple joints may require physical therapy massage, weight loss or surgery. 

If a cat suffers from an FIV co-infection, a course of treatment will likely be administered, though the prognosis is poor. Chronic infections mean these cats will likely require antibiotic and antifungal treatment regularly. If more serious conditions develop (e.g., cancer), aggressive treatments may become necessary.

Cats infected with asymptomatic FeFV will likely live normal lives and require little treatment or management. As the virus and its implications are not fully understood, your veterinarian may suggest you keep your cat indoors or away from other cats as much as possible to prevent transmission. Regular check-up appointments are recommended for cats infected with FeFV to facilitate the early detection of FIV or progressive polyarthritis. 

As previously discussed, a cat with progressive polyarthritis will require ongoing physical therapy and massage to relieve pain and improve mobility. They may also undergo treatment with antibiotics in the event that synovial fluid drawn from the joints shows bacterial infection. 

A cat with FIV should be kept indoors, away from other cats, to prevent the spread of this potentially fatal viral infection. These cats should be spayed or neutered. Raw meat or eggs, which may contain opportunistic bacteria, should be avoided. Regular veterinary check-ups are of the utmost importance for cats infected with FIV to facilitate early intervention for infections.