Like humans, cats are susceptible to species-specific viruses that can compromise their health. Most cats are exposed to at least one feline virus early in life, which can result in acute or chronic illness, so pet owners must understand common viral threats so they can protect and support their feline friends’ health. The Memorial Animal Hospital team outlines the most prevalent feline viruses and strategies to prevent or manage ongoing disease.

Feline respiratory viruses

Respiratory viruses are among the most prevalent and contagious feline viral diseases. In most cats, respiratory viruses cause mild and self-limiting sneezing, congestion, eye discharge, and possible mild fever. Common respiratory viruses include feline herpesvirus (FHV-1) and feline calicivirus (FCV). FHV-1 infection can become problematic for some cats, because the virus isn’t usually cleared from the body and instead lurks in nerve cells and can reactivate and cause illness all over again—usually during times of stress or other illnesses. FHV-1 is a major cause of chronic eye diseases in cats.

Feline leukemia virus

Feline leukemia virus (FeLV) is a potentially life-threatening virus that attacks the immune system, leaving affected cats vulnerable to various infections, blood disorders, inflammatory diseases, and cancer. Infected cats may be lethargic, lose weight, lack appetite, and have a fever, diarrhea, or swollen lymph nodes. FeLV is primarily transmitted through close contact with infected cats, such as grooming or sharing dishes. Most FeLV cats live two to three years after diagnosis, but some can live considerably longer, depending on their body’s reaction to the infection.

Feline immunodeficiency virus

Feline immunodeficiency virus (FIV) is common in outdoor cats or those who engage in territorial fights, as the virus is spread through bite wounds, or occasionally from mother to kittens. FIV in cats is similar to HIV in humans, leading to a compromised immune system and leaving them susceptible to a host of opportunistic infections and inflammatory conditions. Infected cats may show no signs or develop recurrent infections, weight loss, eye disorders, or mouth inflammation. FIV is more common and generally less severe than FeLV, and many infected cats live normal, healthy lives, although some cats who succumb to serious secondary infections may die.

Feline enteric coronavirus

Feline enteric coronavirus is a common virus that can cause mild gastrointestinal (GI) infection or no signs at all. Most cats recover with no problem, but rarely, the virus mutates and causes a disease known as feline infectious peritonitis (FIP). FIP causes fever, weight loss, fluid buildup, and neurological abnormalities, and is almost always fatal. However, promising FIP treatments are becoming more readily available and changing the outlook for affected cats.

Safeguarding cats from viral diseases

Completely eliminating the risk of viral infections in cats is impossible, but you can take steps to minimize exposure, including regular veterinary check-ups and vaccinations for your cat. The core FVRCP cat vaccination, which includes protection against herpesvirus and calicivirus, does not prevent infection entirely but can reduce recurrence rates and disease severity. Additionally, we recommend that all cats receive a feline leukemia vaccine series during kittenhood and that their risk profile be reassessed when they reach adulthood. Routine screening for FeLV and FIV infections is recommended for all kittens and sick adult cats or those at risk of exposure.

Cats with existing viral infections need ongoing health support, such as maintaining a low-stress household and providing high-quality nutrition, to reduce disease flare-ups. Schedule and attend routine check-ups and seek veterinary care if your cat develops concerning health signs, which can worsen quickly in cats with compromised immune systems.

Viral diseases spread easily among cats and can have long-lasting effects, but vaccinating your feline friend and providing routine preventive veterinary care can support their health and well-being. Contact the Memorial Animal Hospital team to schedule a visit if you suspect your cat has a viral illness or another health issue, or if you would like to update or discuss your cat’s vaccines.