Anthelmintic resistance has been widely documented to occur in small strongyles (= cyathostomes) of horses with which of the following dewormers?

Anthelmintic resistance in small strongyles, or cyathostomes, has been notably documented with the use of pyrantel, which is a common dewormer. This resistance can arise due to various factors, including the over-reliance on this class of drugs and inadequate treatment protocols, leading to the survival of worms that are not affected by the medication.

In horses, there has been an increasing recognition that factors such as suboptimal dosing, inadequate frequency of treatments, and the life cycle of cyathostomes can contribute to the development of resistance. Pyrantel's mechanism of action targets neuromuscular function in the parasites, and while it can be effective, it has shown decreased efficacy in populations of cyathostomes that have been exposed repeatedly.

The other dewormers listed, fenbendazole, moxidectin, and praziquantel, have also been used in the treatment of equine parasites, but resistance has not been as widely documented for these specific drugs in small strongyles. Fenbendazole and moxidectin may have varying levels of effectiveness depending on the specific strongyle species and treatment history, while praziquantel primarily targets tapeworms and is not utilized as a standard treatment for cyath