Eucoleus boehmi in dogs: Anthelmintic treatment challenges and impact on olfactory capacity

The nasal capillarid Eucoleus boehmi has gained importance in the veterinary field in recent years. However, much is still unknown regarding its life cycle, geographic distribution, and treatment. This study aimed to evaluate the efficacy of three commercial anthelmintic products against E. boehmi in foxhound dogs and to assess the olfactory capacity of infected individuals. The treatment protocols included moxidectin/imidacloprid (MI) and pyrantel pamoate/febantel/praziquantel (PFP), separately and combined, as well as emodepside/praziquantel (EP) alone. Fecal egg count reduction tests (FECRT) were performed using the mini-FLOTAC technique for evaluating the anthelmintic efficacy. The olfactory capacity was assessed through a natural detection task method. In the first phase, the fecal egg count reduction (FECR) values at day 11 post-treatment (PT) were 58 % (95 % CI: 31 %-77 %) for MI, 35 % (95 % CI: 16 %-65 %) for PFP, and 84 % (95 % CI: 68 %-92 %) for EP. On day 33 PT, the fecal egg count (FEC) was higher in all animals compared with day 0. One month after finishing the first phase of the study, a second phase of the trial was performed, and eligible animals were treated either with a combination of MI/PFP or EP alone. On day 13 PT, FECR was 95 % (95 % CI: 78 %-100 %) in animals treated with MI/PFP and 89 % (95 % CI: 77 %-94 %) in animals that received EP. While EP demonstrated moderate efficacy in both phases, MI and PFP products were ineffective individually but achieved high efficacy when used together. In the olfactory function assessment, there was a moderate negative correlation between the egg counts and the performance of the dog in the test. In general, lower FEC were associated with better performance in the olfactory assessment. Further studies are needed to evaluate additional anthelmintics' efficacy, and to further understand the effect of E. boehmi on a dog's olfactory capacity.