Introduction

Feline immunodeficiency virus (FIV) is a common retrovirus in cats that is thought to share many features in common with the human immunodeficiency virus (HIV), which causes AIDS. Infection with FIV progressively suppresses the cat’s immune system. As a result, the symptoms of so-called “feline AIDS” can vary widely, as the cat’s immune system slowly breaks down.

Symptoms of FIV

Cats infected with FIV can develop a number of different symptoms. Because their immune systems are weakened and unable to function normally, affected cats are predisposed to developing secondary bacterial infections that can occur almost anywhere in their bodies. Initially, most FIV-positive cats develop a mild stage of illness roughly 4 to 6 weeks after infection with the virus. However, their early symptoms may not be noticed even by attentive owners, because most cats continue to behave fairly normally. During this early stage of disease, cats may have no obvious symptoms, or they may develop one or more of the following nonspecific signs:

• Fever
• Swollen lymph nodes
• Lethargy
• Weight loss
• Lack of appetite (inappetance; anorexia)
• Depression
• Diarrhea

They may also become anemic and develop superficial skin infections.

The initial phase of FIV infection is usually followed by a long latent period, during which few if any clinical signs are present. This phase can last for months or years. Most cases of FIV are diagnosed during this incubation period as part of a routine veterinary check-up or during testing for some other condition.

Eventually, FIV enters a terminal phase, during which the viral organisms replicate profusely and cause increasing – and irreversible – suppression of the cat’s immune system. When end-stage symptoms appear, they tend to be associated with secondary opportunistic bacterial infections in or around the mouth, gastrointestinal system, reproductive, urinary and respiratory tracts and eyes. Owners of cats with end-stage FIV disease may notice one or more of the following signs:

• Inflamed gums
• Oral ulcers
• Severe, chronic mouth and gum disease
• Bad breath (halitosis)
• Chronic small bowel diarrhea
• Loss of appetite (inappetance; anorexia)
• Dramatic weight loss (emaciation)
• Recurrent urinary tract infections
• Spontaneous abortions
• Recurrent upper respiratory tract infections
• Sneezing
• Coughing
• Red, inflamed eyes
• Ocular opacity (cloudy eyes)
• Ocular (eye) discharge
• Retinal degeneration or hemorrhage
• Nasal discharge
• Neurologic signs (seizures; behavioral changes; dementia)
• Poor hair coat
• Chronic skin infections
• Chronic ear infections
• Hair loss (abundant)

Many of these conditions can be quite painful. The symptoms may wax and wane for years.

Cats at Increased Risk

FIV infection primarily is a disease of outdoor cats. It is commonly caused by bite wounds, especially as a result of fights between intact males.