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Canine heartworms in coyotes in Illinois
Thomas A Nelson1, David G Gregory, Jeffrey R Laursen
1Department of Biological Sciences, Eastern Illinois University, Charleston, Illinois 61920, USA. cftan@eiu.edu
Journal of Wildlife Diseases
|October 22, 2003
Summary
Heartworm disease in coyotes (Canis latrans) in Illinois showed a 16% prevalence, with higher rates in males and older animals. While it impacted female reproduction, heartworm was a minor factor in coyote population dynamics.
Area of Science:
- Veterinary Parasitology
- Wildlife Ecology
- Canid Health
Background:
- Canine heartworm (Dirofilaria immitis) affects wild canids, including coyotes (Canis latrans).
- Coyotes can act as reservoirs for heartworm transmission to domestic dogs.
- Understanding heartworm's impact on coyote health and populations is crucial for wildlife management.
Purpose of the Study:
- To survey heartworm prevalence and intensity in Illinois coyotes.
- To determine if heartworm intensity correlates with coyote physical condition (body weight, fat levels).
- To evaluate the relationship between heartworm infection and female coyote reproductive success.
Main Methods:
- Necropsy of 920 coyotes harvested by hunters and trappers in Illinois (1995-1997).
- Assessment of heartworm presence, intensity, and location within the cardiopulmonary system.
- Evaluation of physical condition metrics including body weight, kidney fat, and marrow fat.
- Analysis of reproductive parameters in female coyotes, such as breeding status and litter size.
Main Results:
- Statewide heartworm prevalence was 16.0%, higher in males (17.7%) and older coyotes.
- Prevalence increased from northern to southern Illinois.
- Heartworm intensity averaged 8.7 worms, with most coyotes having low-intensity infections (<12 worms).
- No significant correlation was found between heartworm intensity and body weight or fat levels.
- Infected female coyotes exhibited reduced reproductive success, including lower breeding rates in yearlings and fewer offspring in older adults.
- Heavy infections adversely affected fur quality and fecundity in a small percentage of coyotes (4.1%).
Conclusions:
- Heartworm disease is prevalent in Illinois coyotes but generally of low intensity.
- While heartworm infection negatively impacts female reproductive success, it is a minor factor influencing overall coyote population dynamics.
- Coyote populations have increased in Illinois, with little change in heartworm prevalence or intensity over two decades.