Efficacy of two topical combinations containing emodepside plus praziquantel, and emodepside plus praziquantel plus tigolaner, for the treatment of troglostrongylosis in experimentally infected cats

: Feline troglostrongylosis caused by Troglostrongylus brevior is increasingly reported in European countries. Although the disease can be severe and potentially life-threatening, especially in kittens and young cats, effective treatment options are still limited. Two administrations of emodepside 2 weeks apart have shown promising results for the treatment of T. brevior infection in single cases and in a field trial. Therefore, the present study has been conducted to evaluate the efficacy of two spot-on combinations containing emodepside (i.e. 2.14% w/v emodepside and 8.58% w/v praziquantel - Profender®, and 2.04% w/v emodepside, 8.14% w/v praziquantel and 9.79% w/v tigolaner - Felpreva®) in the treatment of troglostrongylosis under experimental conditions. Twenty-four cats were experimentally infected with T. brevior and randomly assigned to one of three groups of eight cats each, i.e. (i) Group 1 (G1) left untreated, (ii) Group 2 (G2) receiving Profender® on Days 28 and 44, and (iii) Group 3 (G3) receiving Felpreva® on Day 28 and Profender® on Day 44. Doses corresponded to the minimum effective dose of 0.140 and 0.148 ml/kg body weight, for Profender® and Felpreva®, respectively. The primary efficacy criterion was the number of viable adult T. brevior counted at necropsy conducted between Days 69 and 72. The fecal shedding of first-stage larvae (L1) was also assessed. L1 of T. brevior were detected in samples from all cats within 20 days post-infection. At necropsy, 4 of 8 G1 cats harbored adult T. brevior, while no adult T. brevior worms or other development stages were recovered from any of the G2 and G3 cats. The primary efficacy criterion was not evaluated as the worm counts in G1 did not meet VICH guideline requirements. After the first treatment (Day 28), most G2 and G3 cats were negative at the Baermann examination. After the second treatment (Day 44), L1 were found in two cats from G2 on Day 49 and in one G3 cat on Day 51. No adverse events occurred in G2 and G3 cats. These results indicate that two applications of emodepside spot-on given 2 weeks apart represent a safe and efficacious treatment regime against troglostrongylosis.