Abstract Background Canine heartworm ( Dirofilaria immitis ), a filarial parasite endemic in many countries worldwide, can cause life-threatening disease in dogs if left untreated. Two laboratory studies and one field study were conducted to evaluate the efficacy of Credelio Quattro, a novel chewable tablet containing moxidectin in combination with lotilaner, praziquantel and pyrantel, for the prevention of heartworm disease caused by D. immitis . Methods In the laboratory studies, dogs were inoculated with 50 D. immitis L3 larvae on Day – 30. Eight dogs per group were randomized to receive either a placebo or Credelio Quattro at the minimum effective dosage of 0.02 mg/kg moxidectin, 20 mg/kg lotilaner, 5 mg/kg praziquantel, and 5 mg/kg pyrantel on Day 0. One of the studies also included a lotilaner-only treated group to demonstrate non-interference. Efficacy was evaluated ~ 150 days post-inoculation utilizing adult heartworm counts collected at necropsy. The field study enrolled client-owned dogs, ≥ 8 eight weeks of age, weighing at least 1.5 kg, from 13 geographically diverse veterinary clinics throughout the USA. Dogs were randomized in a 1:1 ratio to receive either Credelio Quattro or a positive control product, Simparica Trio ® (moxidectin/sarolaner/pyrantel), at the recommended label dosages for 11 consecutive months. Efficacy was evaluated on Day 330 by assessing the detection of adult heartworm infections using antigen and microfilarial tests. Results In both laboratory studies, no adult heartworms were collected from any of the dogs treated with a single dose of Credelio Quattro. In contrast, all dogs treated with placebo (range 13–40) or lotilaner-only (range 9–42) had adults present. A total of 372 dogs were enrolled in the field study (191 Credelio Quattro, 181 Simparica Trio). At the end of the study, no dogs from either treatment group tested positive for adult heartworms. Credelio Quattro was well tolerated in all studies. Conclusions The laboratory studies demonstrated Credelio Quattro as 100% effective for the prevention of heartworm disease caused by D. immitis in dogs. Additionally, no dogs in the field study tested positive for adult heartworm infection after 11 consecutive monthly doses of Credelio Quattro. Graphical abstract
Young et al. (Mon,) studied this question.