HEMOSTATIC DISORDERS IN FELINE IMMUNODEFICIENCY VIRUS-SEROPOSITIVE CATS

The hemostatic function of 40 feline immunodeficiency virus (FIV) sero positive and 8 FIV and feline leukemia virus (FeLV) seropositive cats was evaluated and compared with reference values from 30 clinically he althy cats. The FIV-positive cats were divided into 3 groups: group I included asymptomatic carriers; group II comprised sick FIV-infected c ats with illnesses not likely to influence the hemostatic system; and group III included FIV-positive cats with diseases potentially associa ted with coagulopathies. Platelet counts in FIV/FeLV-infected cats wer e significantly lower than in healthy cats (P < .003), whereas the dif ferences in the 3 groups of FIV-positive cats were variable (group I, P = .009; II, P = .05; III, P = .09). Thrombocytopenia (< 145,000 plat elets/muL) was present in 4 FIV-positive and 3 FIV/FeLV-positive cats. Platelet aggregation induced by collagen (0.5 and 0.25 mug/mL), adeno sine diphosphate (ADP) (1 and 0. 6 mumol/L), and thrombin (0.4 and 0.2 5 IU/mL) was not significantly different from that of healthy cats. Th e plasma coagulation system was evaluated by measuring one-stage proth rombin time (OSPT), activated partial thromboplastin time (APTT), thro mbin time, fibrinogen concentration, coagulation factor assays, fibrin ogen and fibrin degradation products (FDP), and plasma exchange test. The OSPT was similar in FIV-seropositive cats and in the healthy contr ol group. Cats with FIV infection, however, had markedly shorter clott ing times than healthy cats when using a modified test system (P < .05 ). In all groups of FIV-infected cats and in those with FIV/FeLV infec tion, APTT measured with 2 different commercially available tests, and a modified plasma assay was markedly prolonged compared with healthy cats (APTT1 and 2:3 modification: P < .01; APTT2: P < .05 except group III). In 22 of 40 cats with FIV and in 5 of 8 cats with FIV/FeLV infe ction, plasma samples were beyond the reference range. The thrombin ti me was also significantly prolonged in cats with FIV and FIV/FeLV infe ction (P <. 01); values in 17 of 40 FIV-positive cats were above refer ence range. The mean fibrinogen concentration of cats with FIV and FIV /FeLV infection was higher than in the healthy control group (P < .001 ). Factor VIII activity of 4 cats with FIV infection was 1.5 times hig her than that of healthy cats. Factor XII activity of 3 cats from a gr oup of 20 cats with prolonged APTT was between 20% and 35%. Factor IX and XI activities ranged between 70% and 120%. The markedly prolonged APTT in 2 FIV-positive cats could be shortened considerably in a plasm a exchange test using 20% feline pooled plasma. The alterations in the coagulogram of FIV-seropositive cats were not related to a clinical s tage or concurrent diseases. A definite explanation of the distinct di sorder within the intrinsic plasma coagulation system in FIV-infected cats was not found.