Recently, a friend called me about his chocolate Labrador retriever, who was very itchy. In the past, one of his dogs had been treated with a corticosteroid (prednisone) for seasonal allergies, and he thought that perhaps this was the problem again.
He brought his very happy, exuberant Lab, Coco Crisp, over for me to examine and described how intensely itchy he had been to the point where he was scratching through the night. Whenever a veterinarian is presented a case with this degree of pruritus (itchiness) and constant scratching, the first thing he or she considers is sarcoptic mange.
This type of mange, also known as scabies, is caused by the mite Sarcoptes scabii. It causes extreme pruritus, is contagious to other dogs, and can be passed to humans. In humans, it is self-limiting and usually resolves on its own, as we are not the normal host; the mite is very species specific.
The areas most commonly affected are the ear margins, elbows, and hocks; however, it can also spread to the head and abdomen. The intense itchiness and scratching often traumatizes the skin, leading to secondary bacterial infections. Crispy had a classic presentation, with thick crusts over the ear margins along with intense pruritus.
Definitive diagnosis is made by scraping suspect areas with a scalpel blade and examining the scraping microscopically. If present, adult mites, nymphs (immature mites), or eggs may be seen. Because the mite burrows so deeply, it is common to have a negative scraping (no microscopic evidence of mites); however, treatment is indicated based on signs and history alone.
Ivermectin is the drug used to treat sarcoptic mange, and veterinarians will prescribe it either orally or by injection for a period of four to six weeks.
When there is evidence of a secondary skin infection, your veterinarian will also prescribe an antibiotic and often an antibacterial shampoo.
Crispy responded well to a course of treatment consisting of six weekly injections of ivermectin. Their other dog, Chuckles, although very itchy, did not have characteristic lesions over the ear margins and elbows; he seemed to be most itchy over his abdomen. In addition, he had signs of a secondary bacterial skin infection. Nevertheless, we treated Chuckles for four weeks with ivermectin as well as antibiotics and a benzoyl peroxide shampoo. He has also responded well.
Interestingly, the family’s newest addition, a puppy named Koda, has not shown any signs of mange, which is unusual, as young dogs seem to be more prone to the disease. He is being carefully observed for any signs of it. Also, fortunately, no family members ever exhibited symptoms.
East Bare Hill Road resident Fred Karotkin is a veterinarian.
