Feline Viruses and Diseases

Feline Infectious Peritonitis (FIP)

A systemic, viral disease characterized by insidious onset, persistent nonresponsive fever, pyogranulomatous tissue reaction, accumulation of exudative effusions in body cavities, and high mortality.  This virus is multisystemic affecting liver, kidneys, intestines, lungs, brain and eyes.  FIP is a reaction to infection with the feline coronavirus.  The coronavirus mutates and FIP is the result of immunocompromised young cats. FIP is a disease created by the cat’s own immune system.  There are 2 forms of FIP.  The “wet” form includes the effusion of thick, yellow fluid in the belly or chest.  The “dry” form is more insidious, leading to a long, slow death.  Both forms are felt to have 100% mortality. 

Transmission with coronavirus is primarily through infected feces.  Prevention is limited to preventing overcrowding, and exposure to infected feces.  We can test for positive antibodies to the virus, but it does not distinguish between coronavirus and FIP.  There is a vaccine available, but its efficacy is unknown.  There is no known cure or treatment available.

Feline Immunodeficiency Virus (FIV)

FIV is retrovirus that causes an immunodeficiency disease in domestic cats.  It has the same genus as HIV (aids in humans).  Infection disrupts the immune system function causing the cat to become more susceptible to secondary infections.  There is no cure, and treatment is limited to treating the secondary infections.

Transmission is cat-to-cat through bite wounds, and occasionally it can be transmitted perinatally (during birthing). 

Prevention includes preventing contact with other cats, and screening prior to introducing new cats into the household.  There is a vaccine available, but only 60-80% efficacy after 3 doses.  Testing cannot distinguish between vaccinated and infected cats, so vaccinated cats will always test positive.

Feline Leukemia Virus (FeLV)

FeLV is another retrovirus that causes an immunodeficiency disease in cats.  This virus is species specific and does not infect dogs or humans, but there is evidence of the disease in wild cats such as lynx, cheetah and lion.

After the initial infection, the virus replicates in the tonsils and pharyngeal lymph nodes (the pharynx is the muscular tube in the neck). Then it spreads via the bloodstream to other parts of the body, especially the lymph nodes, bone marrow, and intestinal tissue, where it continues to replicate. Viremia, the presence of virus in the blood, usually shows up 2 to 4 weeks after the initial infection.

FeLV usually spreads through infected saliva. It can also spread through infected urine, tears, and feces, and through an infected mother to her kittens during gestation and nursing. Methods of transmission include the following:

  • Bite wounds from infected cats (more common among outdoor and indoor-outdoor cats)
  • Blood transfusions
  • Mouth and nose contact with infected saliva or urine
  • Mutual grooming
  • Nose-to-nose contact
  • Shared food dishes and water bowls
  • Shared litter trays
  • Sneezing

Because cats normally may not appear to be sick until they are in an advanced state of illness, it is vital that cat owners pay close attention to their pets' day-to-day condition. Cats should be examined regularly for painful or swollen areas.  30% of cats infected with the disease will progress and die.  Treatments may help to slow the progression of disease, but are not 100% effective in all cases.

FeLV is one of the most devastating feline diseases worldwide.  Feline leukemia virus (FeLV) infection is responsible for more deaths among cats than any other infectious disease.