Three serious viruses that have no cure—feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and feline infectious peritonitis (FIP)—affect cats of all ages. Vaccines that protect your cat against FeLV and FIV are available, but you can also protect your cat from FIP. We want you to understand these important viral diseases, to help you take good care of your cat’s health. 

#1: Feline leukemia virus

What is FeLV?

FeLV is exclusively a cat disease that can be spread only by close contact between cats, and only from one cat to another. Viral transmission occurs primarily through saliva; for example, from a bite from an infected cat, or through social activities such as grooming, or sharing food and water bowls. FeLV poses no risk to humans or other species.

Kittens can acquire FeLV before birth from infected mothers, or while nursing. The incubation period (i.e., the time between becoming infected and the appearance of clinical signs) is usually short in kittens, but long in adult cats, who may remain symptom-free for years after infection. Some FeLV-positive cats will never demonstrate disease signs, but may still be infectious to other cats.

What are FeLV signs?

FeLV causes anemia, sometimes caused by leukemia, a type of blood cancer. Signs include:

  • Weakness and lethargy
  • Weight loss
  • Diarrhea 

What if my cat is FeLV-positive?

We can perform a quick test that requires only a few drops of blood, and is usually repeated a few weeks later to confirm results. No treatment exists, although many FeLV-positive cats live long, comfortable lives with proper management, which involves excellent veterinary care and vigilant monitoring for any illness signs. 

How can  FeLV be prevented?

Since no treatment exists for FeLV, prevention is key. The American Association of Feline Practitioners recommends:

  • Vaccinating all kittens, starting at 8 weeks of age
  • Boostering the kitten three or four weeks later, and revaccinating at 12 months  
  • Vaccinating indoor-outdoor cats annually; exclusively indoor cats may need need only the 12-month vaccination  
  • Keeping all cats indoors to prevent infection
  • Testing new cats before introducing them to your household 

#2: Feline Immunodeficiency Virus

What is FIV?

FIV damages the immune system of cats and increases their susceptibility to infections from other microorganisms. Sometimes called “cat AIDs,” FIV also can be transmitted only between cats. Transmission is through saliva, so cat bites, and shared food and water bowls pose risks. Mothers can transmit the virus to their kittens through the placenta or milk, but they may not show signs for years. Some FIV-positive cats will successfully fight the disease and never become sick.

What are FIV signs? 

FIV-positive cats typically get recurrent infections, including: 

  • Urinary tract infections
  • Gastrointestinal infections that cause chronic diarrhea
  • Oral ulcerations causing bad breath, gingivitis, and reluctance to eat because of pain  
  • Weight loss
  • Lethargy 

 What if my cat is FIV-positive?

We can perform a rapid test for FIV, although a positive test cannot indicate whether or not your cat will successfully fight off the infection, or how long they will remain healthy before showing disease signs. Kittens who acquire antibodies from their mother may test false-positive—a kitten who tests positive should be retested at 6 months of age, when maternal antibodies typically fade. 

How can I protect my cat against FIV?

  • Keep cats indoors to protect them from other cats’ bites
  • Test new cats before introducing them to your household
  • Vaccinate outdoor cats and FIV-negative cats living with FIV-positive cats, although the vaccine does not provide full protection

#3: Feline infectious peritonitis

What is FIP?

FIP is caused by a mutant form of feline coronavirus (FeCoV) and is transmitted through saliva and feces. FIP is more common in multi-cat households where food and water dishes and litter boxes are shared. Much remains unknown, but FIP seems to most commonly affect kittens and elderly cats. FIP is always progressive and fatal.

What are FIP signs?

The wide variety of FIP signs include:

  • Chronic diarrhea
  • Weight loss
  • Fever
  • Lack of appetite
  • A swollen belly caused by fluid accumulation in the abdomen
  • Difficulty breathing because of fluid accumulation in the chest
  • Jaundice
  • Unsteadiness
  • Change in eye color

What if my cat is FIP-positive?

Confirming FIP can be difficult, because no test distinguishes between the benign FeCoV and FIP, the mutated version. Cats may test positive for FeCoV exposure, but never develop FIP.  Veterinarians usually diagnose FIP based on the cat’s symptoms. A vaccine does exist, but is not recommended because evidence suggests it’s ineffective.

If you have recently welcomed a new kitten, especially if you have other household cats, bring them to our hospital to be tested for these three serious cat viruses. Or, contact us and schedule testing for all your cats, so we can advise you on preventing FeLV, FIV, and FIP, or learning how to manage a cat who tests positive. We are here to help all your cats live long, comfortable lives.