Which of the following is classified as an anthelmintic?

Ivermectin is classified as an anthelmintic because it is specifically designed to treat parasitic infections caused by helminths (worms) in various animal species, including swine. Ivermectin works by disrupting nerve and muscle function in these parasites, ultimately leading to their paralysis and death. Its broad-spectrum efficacy also allows it to target other types of parasites, such as certain ectoparasites.

In contrast, while praziquantel is primarily effective against trematodes and cestodes and is considered an anthelmintic for certain applications, it is not the most related choice in the context of swine compared to ivermectin. Fenbendazole, on the other hand, is also commonly used for gastrointestinal worms, thus classifying it as an anthelmintic as well, but the selection of ivermectin often offers a more comprehensive treatment option in swine. Amprolium is specifically an anticoccidial medication used to prevent and treat coccidiosis rather than an anthelmintic, which is primarily aimed at helminths.