All dogs have demodex mites, but border collies and a few other breeds tend to face infestation more than others. It's not that collies are more appetizing. They just have a high chance of experiencing a negative reaction to the medicine commonly prescribed to treat demodectic mange.
Normally, demodex mites are good and quiet neighbors. They feed on dead skin cells inside your dog's hair follicles without making a fuss. Mothers pass the mites on to their babies shortly after birth, so practically every dog has them. When your dog is healthy, his immune system keeps the mite population at a reasonable level. However, they can get out of control if he develops a skin infection or another ailment that weakens his immune system. Damage from demodex mites produces a condition called demodectic mange, which is similar to infestations of other mange mites.
Sometimes puppies develop a temporary case of demodectic mange when they first inherit the parasites from their mother. While medical treatment is recommended, between 30 percent and 50 percent of pups recover on their own as their immune systems become stronger, according to the Mar Vista Animal Medical Center website. Adult demodectic mange is more serious, because it indicates an immune-damaging disorder. Common symptoms include patches of balding, itchy or scaly skin that may appear in a small area such as the tip of an ear and can spread across your dog's entire body.
Ivermectin and Collies
For most dogs, a prescription of ivermectin or milbemycin would be enough to clear up a case of demodectic mange in a few weeks. Unfortunately, these drugs are not an option for many collies. Border collies, shelties and other herding dogs are predisposed to negative reactions with the two drugs used to manage demodex mites, according to Washington State University College of Veterinary Medicine and other authorities. That doesn't mean your collie will definitely have a bad reaction to them, but the risk is great enough to prevent your vet from starting your collie on a full prescription as a first treatment.
Your vet may start your dog off on a very small dose of ivermectin to check for a negative reaction before giving him a full dose. He may recommend a lab test for the mutant gene if the test is available in your area. If he believes your collie won't tolerate the medicine, he will prescribe a dip solution for you to bath your dog in. Dip your dog in the anti-mite shampoo once every week or two as instructed by your vet.
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