Sarcoptes scabiei var canis infestation is a highly contagious disease of dogs that occurs worldwide. The mites are mostly host specific, but the disease is zoonotic, and humans who come in contact with infested dogs may be infected. Adult mites are 0.2–0.6 mm long and roughly circular in shape; their surface is covered with small, triangular spines, and they have four pairs of short legs. Females are almost twice as large as males. The entire life cycle (17–21 days) is spent on the host dog. Female mites burrow into the stratum corneum to lay their eggs. Sarcoptic mange is readily transmissible between dogs by means of direct contact; transmission via indirect contact may also occur by combs, brushes, towels, and blankets.
Signs & Symptoms of Sarcoptic Mange
Signs of sarcoptic mange can show up anywhere from 10 days to 8 weeks after being near an animal with the mites. Some animals might not show any signs but still carry the mites. The main thing you’ll notice is really bad itching, which happens because the body is reacting to the mites. At first, you might see red, crusty bumps with thick, yellow scabs, and the skin might get scraped and red. Sometimes, there can be infections from bacteria or yeast. These bumps usually start on the belly, chest, ears, elbows, and ankles and can spread all over if not treated.
When sarcoptic mange gets really bad in dogs, they can have serious skin problems like seborrhea, where the skin gets oily and thick with lots of folds and crusts. Their lymph nodes might swell up, and they could lose a lot of weight, even to the point of dying. Sometimes, in well-groomed dogs, it’s hard to tell they have sarcoptic mange because they wash away the crusts and scales when they bathe, but they still itch a lot. There are also different types of sarcoptic mange that show up in unusual ways, especially when dogs are treated a lot with bug-killing products.
Doagnosis
Doctors diagnose sarcoptic mange by looking at the animal’s history, like if they suddenly started itching a lot, if they’ve been around other animals with the same problem, or if humans have been around them and gotten itchy too. Sometimes, it’s hard to be sure because the skin scrapings don’t show anything, but if they look at several samples carefully, they might find the mites, their eggs, or their poop. They usually scrape the ears, elbows, and ankles, focusing on areas that aren’t scraped or irritated. They might also use a special test called a fecal flotation to see if there are mites or eggs in the poop. There’s also a blood test available that can help find specific antibodies, which can be really helpful in diagnosing the disease.
Treatment
To treat sarcoptic mange, vets often use medicines called macrocyclic lactones. One of these, selamectin, is given as a spot-on treatment at a dose of 6–12 mg/kg. It’s usually given just once, but some dogs might need a second dose a month later. Selamectin is safe for dogs, even for breeds that are sensitive to another similar drug called ivermectin.
Another FDA-approved treatment is a combination of imidacloprid and moxidectin, also given as a spot-on treatment. This one is given in two doses, with a month between each dose. It’s important to avoid giving this one orally to breeds that might be sensitive to a similar drug called avermectin, but using it on the skin is usually safe for these dogs.
Some other drugs like milbemycin oxime and ivermectin, although not officially approved for treating sarcoptic mange in dogs, have been used effectively in some cases. For milbemycin oxime, the recommended dose is 2 mg/kg, given by mouth once a week for 3–4 weeks. But it’s important to be careful with dogs that might be sensitive to drugs like ivermectin.
Ivermectin is also very effective against sarcoptic mange. It’s usually given at a dose of 200 mcg/kg, either by mouth or under the skin, with 2–4 treatments spaced two weeks apart. However, it’s not safe to use this dose in breeds that are sensitive to drugs like ivermectin. Before using any of these drugs, it’s also important to check if the dog has any heartworms, because using certain drugs can be risky if the dog already has them.
There are some new drugs called isoxazoline drugs, like afoxolaner, fluralaner, and sarolaner, that have been found to work well against sarcoptic mange in dogs. However, right now, none of these drugs are officially approved by the FDA for treating sarcoptic mange.
If you’re using older treatments that you put directly on the skin, you might need to trim the dog’s hair first and then clean off any crusts and dirt with a special shampoo that fights skin problems. After that, you can use a special bath called a dip that kills the mites. One effective dip is made with lime sulfur, which is safe even for young animals. You’ll need to do several of these dips, about a week apart.
Another option is a solution called amitraz, which kills the mites, but it’s not officially approved for this use. You’d apply it to the skin every one or two weeks for a few weeks.
When using these treatments, it’s important for the owner to be careful not to get the medicine on themselves. There’s also a spray called fipronil that can help, but it’s best used alongside other treatments, not on its own.
Sometimes, it’s hard to find the mites even if the dog seems to have sarcoptic mange. In cases like this, it might be a good idea to try a treatment and see if it helps. It’s actually pretty common for cases of sarcoptic mange to be mistaken for other skin problems, like allergies, and treated the wrong way for a while before figuring out what’s really going on. In serious cases, the dog might need to see a specialist in skin problems for the right treatment.
It’s also important to treat all the dogs that have been around the one with sarcoptic mange to make sure it doesn’t spread.