Effects of canine heartworm (Dirofilaria immitis) on body condition and activity of free-ranging coyotes (Canis latrans)

We used radiotelemetry to study relationships among canine heartworm (Dirof ilaria immitis) infection, body condition, and activity of free-ranging coy otes (Canis latrans). Average body mass at death was lower for 17 coyotes i n a high-intensity infected group ((x) over bar = 33.6 heartworms) than for 18 coyotes in a control group ((x) over bar = 3.6 heartworms; p < 0.01). C oyotes in the infected group lost body mass at an average rate of 20% per y ear relative to the control group (p < 0.01). Bone marrow fat was negativel y correlated with heartworm burden (R-2 = 0.27; p < 0.01). Average body mas s of coyotes at initial capture (i.e., potentially before infection) did no t differ between infected and control groups (p = 0.90; 1-beta = 0.70). Act ivity was negatively correlated with heartworm burden during the last 2 mon ths of life (R-2 = 0.30; p < 0.01), but no correlation was found 2-4 months before death. Activity of the infected group (n = 13) declined over time ( p = 0.01), whereas no difference in activity was observed in the control gr oup (n = 13; p = 0.50). Our findings indicate that heartworm infection redu ced body condition and activity of coyotes but that nutritional status did not significantly affect susceptibility to infection.