I just learned of another sad episode of a dog being poisoned and blinded after lapping up ivermectin dewormer paste, dropped from a horse's mouth after treatment. So it doesn't happen to your dog(s), here are some heads-up points you should know:
* A genetic mutation, known to be present in certain dog breeds (Collies, Shelties, German and Australian Shepherds, for instance, plus mixes derived from them), is responsible for the problem. A dog with this mutation is unable to process the drug effectively out of his system, and suffers reactions--sometimes fatal--as a result. Blindness is common. Learn more here.
(Ed's dog, Ranger, shown above, is a mixed-breed guy tracing to the affected breeds.)
* It may only take as little as 1/4 teaspoon of the deworming drug to cause serious effects in a dog who ingests it. A horse can easily spit out this much, or you can have this much left over in a discarded tube that a dog finds and starts to chew on.
* Dogs find flavored ivermectins--ones made for increased palatability to horses--especially tasty. They may sniff out and eat amounts falling to the ground from treated horses, or may dig through garbage to find discarded tubes of dewormer with residue remaining.
* Scientists at Washington State University have pinpointed the mutated gene, and have developed a test for it. The results will indicate whether your dog is susceptible to poisoning from ivermectin and certain other drugs.
* Play it safe by keeping your dog(s) confined whenever you plan to administer ivermectin to horses. Watch horses closely after giving the drug, to make sure they haven't spit any out. Wipe up anything that falls and discard safely. Store tubes of ivermectin paste, whether new or used, out of dogs' reach. Dispose of used tubes with care.
* Never give leftover equine dewormer to your dog!