Efficacy of Simparica Trio® (sarolaner, moxidectin, and pyrantel chewable tablets) against circulating microfilariae in dogs infected with Dirofilaria immitis.
5 affiliations
- 1Zoetis, Veterinary Medicine Research and Development, Zoetis Australia, Rhodes, NSW, 2138, Australia. [email protected].
- 2College of Veterinary Medicine, Chonnam National University, 77 Yongbong-ro, Gwangju, 500-757, South Korea.
- 3Zoetis Korea, 412 Teheran-ro, Gangnam-gu, Seoul, 06193, South Korea.
- 4Zoetis Inc, 333 Portage Street, Kalamazoo, MI, 49007, USA.
- 5Zoetis, Veterinary Medicine Research and Development, Mercuriusstraat 20, 1930, Zaventem, Belgium.
Abstract
Background
Canine heartworm disease remains a global threat despite the availability of multiple preventive options, a challenge compounded by the emergence of macrocyclic lactone-resistant heartworm strains, especially in the USA. Circulating microfilariae play a pivotal role in heartworm transmission, serving as a continuous infection reservoir for mosquito vectors. Therefore, targeting this life cycle stage is critical in the framework of a comprehensive and multimodal heartworm prevention strategy.Methods
A randomised, blinded, negative-controlled laboratory study evaluated the efficacy of Simparica Trio® (Zoetis Inc., Parsippany, NJ, USA), containing a minimum dosage of 1.2 mg/kg sarolaner, 24 µg/kg moxidectin, and 5 mg/kg pyrantel, against circulating microfilariae. Dogs naturally infected with heartworm and harbouring circulating microfilariae were enrolled in the study. Twelve dogs received a single treatment with Simparica Trio as per recommended label dosage, and efficacy was compared with an untreated control group of 10 dogs weekly for 28 days.Results
There were no adverse events recorded in this study. Following a single oral dose of Simparica Trio, a significant reduction in microfilaria counts in the Simparica Trio-treated group relative to the control group was first detected within 7 days (P < 0.0001), resulting in an efficacy of 99.9% (98.9%) based on geometric (arithmetic) means. The efficacy remained at least 99.9% (≥ 99.5%) based on geometric (arithmetic) means for 28 days (P < 0.0001).Conclusions
A single oral dose of Simparica Trio was highly effective against circulating microfilariae in naturally infected dogs with D. immitis for 1 month. Combining its effects on migrating L₄ stages and circulating microfilariae coupled with mosquito killing, Simparica Trio offers a multimodal, holistic, integrated solution to heartworm prevention in dogs.
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BibTeX
@article{packianathan2026efficacy,
title = {{Efficacy of Simparica Trio® (sarolaner, moxidectin, and pyrantel chewable tablets) against circulating microfilariae in dogs infected with Dirofilaria immitis.}},
author = {Raj Packianathan and Kyu Sung Ahn and SungShik Shin and Hyeonjo Cho and Jihae Kim and Jessica Rodriguez and Thomas Geurden},
journal = {Parasites \& vectors},
year = {2026},
month = oct,
doi = {10.1186/s13071-026-07733-2},
url = {https://europepmc.org/article/MED/42907840},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Efficacy of Simparica Trio® (sarolaner, moxidectin, and pyrantel chewable tablets) against circulating microfilariae in dogs infected with Dirofilaria immitis.
AU - Raj Packianathan
AU - Kyu Sung Ahn
AU - SungShik Shin
AU - Hyeonjo Cho
AU - Jihae Kim
AU - Jessica Rodriguez
AU - Thomas Geurden
PY - 2026
DA - 2026/10/20
JO - Parasites & vectors
DO - 10.1186/s13071-026-07733-2
UR - https://europepmc.org/article/MED/42907840
AB - Background Canine heartworm disease remains a global threat despite the availability of multiple preventive options, a challenge compounded by the emergence of macrocyclic lactone-resistant heartworm strains, especially in the USA. Circulating microfilariae play a pivotal role in heartworm transmission, serving as a continuous infection reservoir for mosquito vectors. Therefore, targeting this life cycle stage is critical in the framework of a comprehensive and multimodal heartworm prevention strategy.Methods A randomised, blinded, negative-controlled laboratory study evaluated the efficacy of Simparica Trio® (Zoetis Inc., Parsippany, NJ, USA), containing a minimum dosage of 1.2 mg/kg sarolaner, 24 µg/kg moxidectin, and 5 mg/kg pyrantel, against circulating microfilariae. Dogs naturally infected with heartworm and harbouring circulating microfilariae were enrolled in the study. Twelve dogs received a single treatment with Simparica Trio as per recommended label dosage, and efficacy was compared with an untreated control group of 10 dogs weekly for 28 days.Results There were no adverse events recorded in this study. Following a single oral dose of Simparica Trio, a significant reduction in microfilaria counts in the Simparica Trio-treated group relative to the control group was first detected within 7 days (P < 0.0001), resulting in an efficacy of 99.9% (98.9%) based on geometric (arithmetic) means. The efficacy remained at least 99.9% (≥ 99.5%) based on geometric (arithmetic) means for 28 days (P < 0.0001).Conclusions A single oral dose of Simparica Trio was highly effective against circulating microfilariae in naturally infected dogs with D. immitis for 1 month. Combining its effects on migrating L₄ stages and circulating microfilariae coupled with mosquito killing, Simparica Trio offers a multimodal, holistic, integrated solution to heartworm prevention in dogs.
SN - 1756-3305
ER -