It has been known for some time that some Collies experienced an adverse reaction to certain drugs of which Ivermectin, although not licensed for dogs, was possible the most commonly used. Recent research has indicated that this is caused by a gene mutation sometime in our early history which also affects related breeds, and that the problem is not confined to Ivermectin but embraces a whole subgroup of drugs, many of which are licensed for dogs, that are used in a wide spectrum of illnesses.

We strongly advise owners read the label for active ingredients before purchasing over the counter medications, and as many vets remain ignorant about this development it is up to the owner to ensure that under no circumstances must any of the following active ingredients be used on a Collie, without first ensuring that the Collie does not carry the defect  MDR-1  gene.

To ensure you are aware of the most up to date information, please see the link to Washington State University, Problem drugs HERE