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Review
. 2024 Jun 24:11:1377718.
doi: 10.3389/fvets.2024.1377718. eCollection 2024.

A review of moxidectin vs. other macrocyclic lactones for prevention of heartworm disease in dogs with an appraisal of two commercial formulations

Kennedy Mwacalimba  1 , Jenifer Sheehy  2 , Christopher Adolph  2 , Molly Savadelis  3 , Kristina Kryda  3 , Barbara Poulsen Nautrup  4
Affiliations
Review

A review of moxidectin vs. other macrocyclic lactones for prevention of heartworm disease in dogs with an appraisal of two commercial formulations

Kennedy Mwacalimba et al. Front Vet Sci. .

Abstract

Macrocyclic lactones (MLs) are the only drug class currently licensed for heartworm disease prophylaxis. Macrocyclic lactones kill third- and fourth-stage larvae of Dirofilaria immitis, thus preventing the development of adult worms in dogs, which are responsible for heartworm disease, a potentially life-threatening condition. Despite considerable overlap in terms of endectocide spectrum, several important differences distinguish moxidectin from other MLs. Moxidectin has beneficial pharmacokinetic characteristics, such as a longer half-life and greater tissue distribution compared to ivermectin. Additionally, moxidectin has a greater margin of safety compared to ivermectin in dogs with ABCB1 (previously MDR1) gene-defect, which is commonly recognized in collies and other breeds. Multiple laboratory studies have shown that moxidectin is more effective than other commonly used heartworm preventives against resistant strains of D. immitis. This improved efficacy benefits individual dogs and helps reduce the risk of spreading resistant strains within the community. Despite the presence of proven resistant strains in the United States, non-compliance with preventive measures remains a major factor contributing to the diagnosis of heartworm disease in dogs. In retrospective analyses, the oral moxidectin combination product Simparica Trio® (sarolaner, moxidectin, and pyrantel) was associated with increased compliance, resulting in more time of protection compared to dogs receiving flea/tick and heartworm preventive products separately. Compliance with the extended-release moxidectin injectables ProHeart® 6 and ProHeart® 12 was higher than with monthly heartworm preventives, as they provide 6 months or a full year of protection with one single injection, respectively, and revenues remain in the veterinary clinics as injectable moxidectin cannot be sourced through online retailers.

Keywords: Dirofilaria immitis; compliance; dog; heartworm; macrocyclic lactone; moxidectin; prevention; resistance.

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Conflict of interest statement

At the time the study was conducted, KM, JS, CA, MS, and KK were employees of Zoetis. BPN was paid external consultant to Zoetis. BPN was principal of EAH-Consulting. The authors declare that this study received funding from Zoetis. The funder had the following involvement in the study: decision to submit it for publication.

Figures

Figure 1
Figure 1
Lifecycle of Dirofilaria immitis in the dog (2) (L, Larvae; MF, Microfilariae).
Figure 2
Figure 2
Mode of action of macrocyclic lactones (ML). The green circles represent glutamate for the glutamate-gated ion channels.
See this image and copyright information in PMC

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