Younger dogs of specific breeds are more likely to experience a rare adverse event after administration of extended-release injectable moxidectin heartworm preventive.

OBJECTIVE

To estimate the incidence of and identify patient risk factors for an acute adverse event in dogs after administration of a sustained-release injectable heartworm preventive product.

ANIMALS: Canine patients that received the injectable heartworm preventive product during routine preventive care visits.

METHODS

Retrospective analysis of electronic medical records of canine visits within a large network of primary care veterinary clinics in which the product was administered from January 1, 2016, through December 31, 2020. Visits during which vaccination(s) were also administered were excluded from analysis. Identification of acute adverse events was based on diagnostic entries and other clinical presentations suggestive of an adverse event within 3 days of product administration. Data were analyzed using mixed-effects logistic regression.

RESULTS

In the 5-year study period, 1,399,289 visits with 694,030 dogs led to an incidence estimate of approximately 14.3 events/10,000 doses. Regression analysis found younger dogs and 7 breeds (relative to mixed-breed dogs) to have statistically significant greater odds of an event.

CLINICAL RELEVANCE: Understanding of incidence and patient risk factors provides veterinary professionals and dog owners more information when deciding on heartworm preventive options for their dog when considering risk for adverse event in dogs of certain ages or breeds.