Clinical signs

There are 3 stages involved in the clinical FIV disease.  In the first stage, the cat becomes infected resulting in a primary phase of infection, which occurs as the virus distributes throughout the body. This results in a low-grade fever, neutropenia and generalized reactive lymphdenopathy. Cats in this stage normally present with non-specific signs such as anorexia, depression and weight loss (10).  This stage may last several for days to weeks. (6)

 FIV Cat

Cats usually recover from this primary infection and appear healthy though they are still carrying the virus and have only moved into the sub clinical phase of the disease.  This apparently asymptomatic stage varies in the length of time depending on amount of initial viremia, viral strain and age of cat. (6)


In the terminal phase the cat is has now moved into the stage of feline acquired immunodeficiency syndrome which is the equivalent of human AIDS (acquired immunodeficiency syndrome).

The cat is now susceptible to secondary infectious diseases from viral, bacterial, protozoal or fungal origin as its immune system degrades (3). Stomatitis is commonly seen due to chronic antigenic stimulation or immune dysregulation. Other clinical signs are ocular disease, respiratory disease and diarrhea due to an overgrowth of normal bacteria in the gut. (6)

Ocular Lymphosarcoma


FIV infected cats are also statistically more prone to developing neoplasias such as lymphoma and leukemia than other cats. The tumors are generally of B-cell origin. (6)

 Approximately 5% of cats will show neurological manifestations due to FIV (micro). Behavioral abnormalities are most commonly associated with dementia, hiding, rage, inappropriate elimination and roaming. The infected cats may also seizures and show nystagmus, ataxia and peripheral nerve abnormalities due to primary viral effects (6,11).

Table 1.1 Secondary Infections following FIV (11)

Clinical Syndrome

Primary Viral Effect Opportunistic Agents

Skin lesions

(Dermatitis, Otitis externa)
none Mycobacterium spp., Otodectes cyanotis, Demodex cati, Notoedres cati, Cryptococcus neoformans


yes Cryptosporidium, Cystoisospora, Giardia, Salmonella, Campylobacter jejuni
<>Renal Disease

yes FeLV, FIP, SLE

Hematological disorders

(nonregenerative anemia, neutropenia, thrombocytopenia)
yes Haemobartonella felis, FeLV

Neoplasia (lymphoma)

yes FeLV

Neurologic (behavorial abnormalities)

yes Toxoplasma gondii, Cryptococcus neoformans, FHV-1

Ocular disorders (pars planitis uveitis)

yes Toxoplasma gondii, Cryptococcus neoformans, FIP, FHV-1
<>Pneumonia / Pneumonitits
none Toxoplasma gondii, Cryptococcus neoformans


none bacterial


none Calcivirus, overgrowth of bacterial flora, candidiasis

Upper Respiratory Tract

none FHV-1, calcivirus, overgrowth of bacterial flora, Cryptococcus neoformans

Urinary Tract Infection

none Bacterial

FeLV: feline leukemia virus

FIP: feline infectious peritonitis

SLE: systemic lupus erythematosus

FHV-1: feline herpes virus-1