Safety and efficacy assessment of a chewable tablet containing sarolaner, moxidectin, and pyrantel in the treatment of Angiostrongylus vasorum in dogs.

Abstract

Angiostrongylosis, caused by Angiostrongylus vasorum, is an important clinical disease in dogs in Europe with infection transmitted through infected snails and slugs which function as intermediate hosts. Previous studies demonstrated the preventive efficacy of a monthly administration of moxidectin in combination with sarolaner and pyrantel (Simparica Trio&#xae; chewable tablet (SMP); Zoetis). An experimental infection study and a field study were conducted to evaluate the efficacy and safety of SMP for the treatment of infections with adult stages of A. vasorum in dogs. The experimental study evaluated the efficacy of a single (n&#x202f;=&#x202f;7 dogs) or repeated dose (n&#x202f;=&#x202f;8 dogs) of SMP at the minimum recommended dose of 1.2&#x202f;mg/kg sarolaner, 0.024&#x202f;mg/kg moxidectin and 5&#x202f;mg/kg pyrantel (as pamoate salt) administered as a chewable tablet. against an induced infection with 200 (&#xb1;10) L3 A. vasorum at least 63 days prior to treatment on Day 0, compared to a placebo control product (n&#x202f;=&#x202f;8 dogs). Efficacy was determined based on adult worm counts 56 or 57 days after treatment. The field study at veterinary practices in Italy and Denmark evaluated the efficacy and safety of SMP in client-owned dogs (n&#x202f;=&#x202f;66). Advocate&#xae; Spot On (100&#x202f;mg/mL (minimum 10&#x202f;mg/kg) imidacloprid +&#x202f;25&#x202f;mg/mL (minimum 2.5&#x202f;mg/kg) moxidectin from Elanco Animal Health, n&#x202f;=&#x202f;37) was used as the control product. Treatment was administered on Day 0 and repeated on Day 30 if the dog was still positive for A. vasorum larvae. Faecal samples were collected and analyzed with the modified Baermann method in-between scheduled visits. In the experimental study the percentage reduction in geometric mean adult worm counts compared to the placebo-treated group was 98.3&#x202f;% (P&#x202f;<&#x202f;0.0001) after a single dose of SMP and 99.6&#x202f;% (P&#x202f;<&#x202f;0.0001) after two doses. In the field study, faecal larvae counts were reduced by 90&#x202f;% or more in 90.9&#x202f;% of the dogs in the SMP-treated group at Day 30 and in 98.5&#x202f;% of dogs at Day 60. Compared to the pre-treatment faecal larvae counts a geometric mean percent reduction of 96.7&#x202f;% was observed on Day 30 and 99.1&#x202f;% on Day 60 in the SMP treated group. Both in the experimental and in the field study, SMP as a chewable tablet was well tolerated and resulted in a high efficacy against adult A. vasorum infections after a single treatment.