You’ve treated for fleas, and that dog in your shelter is still itching. Should you assume he has allergies? Maybe not.

Veterinary dermatologist William Miller of the Cornell University College of Veterinary Medicine told shelter veterinarians at the recent North American Veterinary Conference that dogs with localized demodex injai often have symptoms mistaken for allergic dermatitis. They’re itchy, frequently on the face – a common site for allergic itching in dogs. Like some dogs with allergies, they also may have a greasy coat. They may have yeast overgrowth, like dogs with allergies. And d. injai can even cause external ear inflammation, usually considered a sign of allergies in dogs.

It’s an important distinction to make in shelters. Allergies that cause itching and other skin symptoms can deter some adopters, who may not feel up to the task of managing a pet with allergic dermatitis. And although dogs in shelters may be under too much stress to fight off the mite on their own, veterinary dermatologist Alice M. Jeromin reported at the 2012 Western Veterinary Conference that localized d. injae clears up on its own as much as 90 percent of the time.*

Distinguishing between the two conditions can also be important because steroids or other immune-suppressing drugs, such as Atopica, typically given for allergic skin symptoms can make demodicosis worse – sometimes much worse, as graphic images shown by Dr. Miller demonstrated.

While considered as easy to treat as the more-familiar d. canis, d. injai mites can be tougher to diagnose. That’s because, said Dr. Miller, “You have to get under and squeeze up, to get capillary oozing” before scraping or plucking hairs to test for the mites. He offered one tip that might help shelter veterinarians tell the difference: “If the dog has atopy, the coat may be greasy in itchy areas. In d. injai, the dog will be greasy all over, not just in areas of hair loss.”

The takeaway message? The next time you see a dog you think has allergies, take the time to dig a little deeper. When it comes to skin symptoms, things aren’t always what they seem.

*Generalized demodicosis is more serious than localized, is almost always associated with underlying immune disease, and is much more difficult to treat.