Haematological changes of experimental feline immunodeficiency virus (FIV) infection in six inoculated and six control cats were studied over a 98 week period. Acute infection was characterised by moderate to severe leucopenia, neutropenia, and eosinopenia between weeks 5 and 13 post-inoculation (PI). Normal myeloid activity or mild myeloid hyperplasia with a left shift to promyelocytes accompanied neutropenia. Chronic infection was characterised by intermittent neutropenia in three of six cats beginning after week 50 Pl and lymphopenia in two cats starting on week 66 Pl. The severity and duration of neutropenia and lymphopenia varied in individual cats. In contrast to natural FIV infections, anaemia and thrombocytopenia did not develop in either acute or chronic experimental infection. Age-related haematological changes such as increasing packed cell volume and plasma protein concentration as well as decreasing neutrophil and total leucocyte counts were noted as both control and inoculated cats reached maturity. The mechanisms of neutropenia and eosinopenia remain unknown. Viral infection of myeloid cells may be involved in the pathogenesis of cytopenias, and further studies are needed to elucidate the mechanisms. This study also demonstrated that FIV infection in cats may be a useful model in studying haematological abnormalities associated with other immunodeficiency-causing lentiviruses.
- Feline immunodeficiency virus
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