MICROFILARIEA IN THE FREE-RANGING FLORIDA PANTHER (FELIS-CONCOLOR CORYI)

Blood samples from Florida panthers (Felis concolor coryi) collected f rom 1986 to 1993 during the months of December through May were screen ed for the presence of microfilariae (mff) by the Difil(R) filter test . Thirty-five of 47 (74.5%) panthers older than 2 yr of age were posit ive with microfilaremias ranging from 10 to 7,380 mff/ml of whole bloo d. No panthers that were 6 mo of age or less (n=10) were microfilariae -positive, and only 20% of the panthers in the 1-yr class (n=5) were p ositive. A representative number of microfilariae (n=40) from each of 7 freshly collected positive blood samples was measured and morphologi cal characteristics were noted. The average length of microfilariae pr ocessed by the modified Knott's technique was 320 mu m (273-370 mu m) with a width of 4-5 mu m. Of the 280 microfilariae measured, 202 (72.1 4%) had tapered heads and straight tails with an average length of 319 mu m (276-368 mu m), 61 (21.79%) had blunt heads and straight tails a nd averaged 323 mu m (274-366 mu m), 16 (5.71%) had tapered heads and button-hooked tails with an average length of 320 mu m (290-368 mu m), and 1 (0.35%) had a blunt head and button-hooked tail and measured 32 0 mu m. The finding of no significant difference (P >0.05) between len gth measurements due to differences in head and tail shape leads us to believe that all microfilariae were of 1 species. Based on microfilar ial length measurements, review of necropsy reports, and comparison wi th bobcat microfilariae, the most likely filarial species infecting th e Florida panther is Dirofilaria striata (Molin, 1858).