Ivermectin is a very commonly used wormer, suitable for horses, cattle, sheep, birds, and a wide range of small mammals. It is occasionally used in dogs – but never in collies and other herding breeds. What is Ivermectin? Ivermectin is part of a family of drugs called the avermectins (which, in turn, are one variety … Continue reading Why shouldn’t my collie have ivermectin wormers?