rrrr

Though all four can be used it should be noted that Fasciola hepatica has began to show resistance to triclabendazole. These dewormers should not be used incessantly due to the development of antibiotic resistance in these liver flukes. Albendazole and Clorsulon are the only two anthelmintics that are approved in the United States of America currently so they must be used sparingly. 

Deworming is typically done twice, in 2 to 3 week periods, and should be given to any of the animals showing clinical signs. Some herd managers may decide to treat the entire herd especially if multiple animals are showing signs and have grazed the same pasture. This however is due to the discretion of the herd manager and a consulting veterinarian. It also may be beneficial to rotate what anthelmintic is used f reinfection occurs so there is little chance of resistance against the dewormers.