Patterns of antiparasitic usage in Golden Retriever breed of dogs: A 9-year cohort study

Antiparasitic agents are routinely used in companion animal medicine. However, longitudinal evidence describing real-world usage patterns in dogs remains limited. This study aimed to characterise patterns, routes of administration, temporal trends, and seasonal variation in antiparasitic drug use among Golden Retrievers enrolled in a large prospective cohort study in the United States. A descriptive analysis was conducted to summarise antiparasitic usage data from the Morris Animal Foundation's Golden Retriever Lifetime Study over nine study years (corresponding to years 0 to 8). Percentages with respective 95% CI were used to summarise drug types, therapy combinations, routes of administration, and temporal and seasonal patterns of use. A total of 17,715 antiparasitic use records were analysed. Drug usage pattern was highly concentrated within a limited number of products, with the ivermectin-pyrantel pamoate combination accounting for 23.0% of all recorded use. Other commonly used agents included afoxolaner (9.73%), metronidazole (9.16%), and lufenuron-milbemycin oxime (8.95%). Oral formulations were predominant, representing 65.28% of all administrations. Single-agent therapy accounted for 47.27% of use, while two-drug combination therapy represented 46.65%. The antiparasitic medications spanned multiple pharmacological classes targeting both endo- and ectoparasites, including anthelmintics, ectoparasiticides, and antiprotozoals. Antiparasitic use declined by 1.8% over the study period. We observed a seasonal variation in antiparasitic drug usage, with higher usage during cooler months (winter) and lower use in summer. These findings provide baseline evidence of the burden of endoparasites and ectoparasites in Golden Retriever dogs and highlight the need for stewardship-oriented parasite control strategies in companion animal practice.