CAPC statement addresses reports of resistance to heartworm preventives in south-central region

National Report.

-- The Companion Animal Parasite Council (CAPC) issued a statement to address reports in the south-central region about increasing problems with resistance to macrocyclic lactones to prevent heartworm disease in dogs.

"There is a growing body of anecdotal reports and experimental evidence that currently available heartworm preventives (macrocyclic lactones) may not be completely efficacious in preventing heartworm infection in dogs. Reports of resistance for dogs in the region have resulted in confusion about how best to prevent infection in veterinary patients," CAPC reports.

Since the vast majority of heartworm cases are the result of failed product compliance, CAPC wants veterinarians to continue recommending year-round heartworm prevention.

"At this time, reports of resistance appear to be confined to dogs from the south-central United States where dogs have become infected while on preventives or remain infected following treatments.

"Veterinarians should also continue to emphasize the need for heartworm diagnostic tests at recommended intervals and appropriate times," the statement says.

The organization says it will continue to monitor ongoing research and make updated recommendations on best preventive strategies as additional information becomes available.