Clinicopathological and Epidemiological Findings in Pet Cats Naturally Infected with Feline Immunodeficiency Virus (FIV) in Australia

Abstract

Feline immunodeficiency virus (FIV) infection in experimentally infected domestic cats produces characteristic clinical manifestations including hematological changes, neurological disease, neoplasia (most notably lymphoma) and lymphopenia-mediated immunodeficiency predisposing cats to a range of secondary infections. Conflicting reports exist, however, with regard to disease associations and survival time in naturally FIV-infected cats. The purpose of this retrospective case–control study was to investigate the effect of natural FIV infection on hematological, blood biochemical and urinalysis parameters and survival time in three cohorts of pet cats in Australia. Cohorts 1 and 2 were recruited from a large veterinary hospital in Melbourne, Victoria (n = 525 and 282), while a third cohort consisted of cats recruited from around Australia as part of a FIV field vaccine efficacy trial (n = 425). FIV-infected cats in cohorts 1, 2 and 3 were found to have 15/37 (41%), 13/39 (33%) and 2/13 (15%) clinicopathological parameters significantly different to FIV-uninfected cats, respectively. Two changes in FIV-infected cats in cohort 1, hypochromia (low hemoglobin) and hyperglobulinemia, were outside the supplied reference intervals and should serve as diagnostic triggers for FIV testing. Kaplan–Meier survival analysis of cats in cohorts 1 and 2 combined did not find any difference between FIV-infected and FIV-uninfected cats, however a confounding factor was a large euthanasia rate within the first 12 months in both groups. Three significant (p < 0.05) spatial clusters of FIV infection were identified in Melbourne. A possible relationship between FIV infection status and socioeconomic disadvantage was discovered, based on three government indices of socioeconomic status (p < 0.001). Until longitudinal field studies are performed in Australia to further investigate the long-term effects of natural FIV infection, Australian veterinarians should consider FIV to be an important infection of pet cats, and recommend measures to prevent FIV infection.

A Retrospective Comparative Evaluation of Selected Blood Cell Ratios, Acute Phase Proteins, and Leukocyte Changes Suggestive of Inflammation in Cats

“…In fact, SAA is a feline major positive APP [ 6 , 53 ], protecting tissues from excessive damage induced by inflammation and acting to regulate the inflammatory process and the immune response [ 54 , 55 ]. Hyperglobulinemia can be observed in both feline inflammatory [ 30 , 31 ] and infectious diseases [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Furthermore, in the serum protein electrophoretic evaluation, most of the positive APPs migrate as alpha- or beta-globulins, and immunoglobulins are beta- and gamma-globulins; thus, a globulin increase can give information about the presence of inflammatory and immune-mediated conditions [ 6 ].…”

“…In cats, serum amyloid A (SAA) and α-1-acid glycoprotein (AGP) are major APPs, haptoglobin is a moderate APP, and C- reactive protein and ceruloplasmin are minor APPs [ 6 ]. Most APPs are globulins, and hyperglobulinemia also reflects the increased production of other proteins, particularly immunoglobulins, that can be observed in both inflammatory non-infectious [ 30 , 31 ] and infectious diseases [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Moreover, the albumin-to-globulin ratio (AGR), routinely reported in the biochemical profile, is considered a screening marker for dysproteinemia observed in feline inflammatory conditions [ 34 , 40 , 41 ].…”

The Late Asymptomatic and Terminal Immunodeficiency Phases in Experimentally FIV-Infected Cats—A Long-Term Study

“…There is controversy regarding the clinical relevance of FIV in naturally infected cats [ 14 ] as some investigators believe that FIV itself does not cause severe clinical disease, and FIV-infected cats live many years without any health problems [ 15 ]. Early epidemiological studies suggested environmental factors such as indoor housing versus outdoor free-roaming status impacted FIV infection status [ 16 ].…”