Characteristics of Mange that May Lead to Misdiagnosis
Mange is commonly misdiagnosed as allergic dermatitis, for two main reasons.
Mange indeed resembles allergic dermatitis, as both are signaled by pruritis (intense itching), self-mutilation due to scratching, patches of crusty skin and hair loss.
Secondly, taking skin scrapings, while effective in detecting other skin parasites, like ear mites, is not nearly as effective in detecting sarcoptic mites, which are microscopic and very elusive.
Two Ways to Test for Mange in Dogs, Including Using Ivermectin
One way to test for scabies, especially useful in dogs that cannot take Ivermectin, is to perform the Pedal-Pinna Reflex Test, in which the pinna, or ear flap, is grasped by thumb and forefinger and scratched on the underside, to see if a dog reflexively begins a scratching motion with the back leg. Dogs without a scabies infection will rarely if ever exhibit this behavior. Dogs with scabies mites in the skin almost always will.
Another way to test for scabies is to administer Ivermectin to dogs to see if the symptoms of mange cease, which would favor a diagnosis of mange over allergic dermatitis. In fact, some medical institutions will not test for allergic dermatitis until sarcoptic mange is ruled out in this manner. Distinguishing between mange and allergic dermatitis at the outset is extremely important, because the treatment for allergic dermatitis-cortisone-has been shown to significantly accelerate proliferation of scabies mites in dogs.
Ivermectin Used Safely Can Kill Scabies Mites in Dogs
Because Ivermectin has not yet been approved by the Federal Drug Administration as a treatment for scabies in dogs, your vet will need your consent to prescribe it to your dog. At the same time, you should know that Ivermectin is used routinely as a safe and effective de-wormer for livestock. Moreover, it is the active ingredient in heartworm preventatives given to pets. Due to its growing reputation as an effective treatment for scabies in dogs, many veterinarians are beginning to add it to their traditional arsenal containing chemical dips and sprays. The key to making sure Ivermectin is safe for your dog is to administer the correct dosage. Follow your vet's instructions to the letter if your dog is taking Ivermectin, for an overdose of Ivermectin can be fatal.
When Ivermectin May Not Be Safe for Your Breed of Dog
Some dogs in herding breeds possess a genetic mutation, MDR1, which makes them unable to safely absorb Ivermectin into their system. As a result, dogs with this mutation may experience grave neurological symptoms if given Ivermectin, even death. MDR1 has been identified in Collies, Shelties, Australian Shepherds, Old English Sheepdogs, German Shepherds, Long-haired Whippets, Silken Windhounds, among several mixed breeds as well.
Fortunately, your vet can order a test involving a simple cheek scraping to determine if your dog can take Ivermectin safely or not. Moreover, your vet can prescribe new and effective topical treatments for scabies instead of Ivermectin.