March 31, 2021
The most commonly used tests to diagnose scabies are skin scrapings, which aim to scrape out a few mites from their skin "burrows". These mites can then be identified when the scraped sample is examined under a microscope. The preferred areas for skin scrapings are the elbows, hocks, and chest, as there is a higher chance of finding the mites there. Ear tips are sometimes scraped too.
The hair is usually clipped from the site, then a scalpel blade doused with a little mineral oil scraped across the skin. The skin and debris collected on the scalpel blade are wiped onto a slide and examined under a microscope by the veterinarian.
Unfortunately, Sarcoptes mites are very difficult to find. If a single mite or egg is seen, this confirms the disease, however if none are found, this does not rule sarcoptic mange out. In fact, only about 20 percent of cases will have a positive scrape.
Another common sign indicating the presence of Sarcoptes mites is the pinnal-pedal reflex (pinna is the ear flap, pedal is the hind foot). This involves rubbing the ear margin between the thumb and forefinger in the hope of eliciting a scratch reflex with the hind leg on the same side as the ear. If positive, this is highly suggestive of scabies and occurs in around 75 percent of cases.
What is the best treatment for mange in dogs?
All in-contact dogs and cats must be treated, as the disease is highly contagious. The mites on infected animals must be killed and any bacterial infections should be treated with antibiotic medications. For severe itching, veterinarians will often prescribe anti-inflammatory medications to provide some relief.
Estimates of how long the mites can survive away from a host vary widely, from less than 24 hours up to three weeks. So, while in a worst case scenario, mites will be virtually eliminated from the environment within a couple of weeks, it is still advisable to treat the environment and the pet's bedding to speed the death of the mites.
There are a number of treatments that can be used to kill mites:
- Selamectin (Revolution): Two monthly treatments are required for the treatment of sarcoptic mange in dogs. Trials in the US and Europe demonstrated that based on skin scrapings, the efficacy of selamectin against Sarcoptes infestations on dogs was greater than 95 percent by day 30, and 100 percent by day 60.
- Fipronil (Frontline) has a claim to aid in the control of scabies.
- Amitraz washes and dips, such as Demadex Acaricidal Dog Wash and Mitaban are also approved for the treatment of sarcoptic mange. For maximum effect, the dog should be completely clipped of all hair and bathed in a shampoo which cleans out the pores of the skin and encourages the mites to move towards the skin surface prior to treatment with a dip. Shampoos containing benzoyl peroxide are ideal for this pre-wash.
- The dip solution should be diluted to the appropriate strength with water, then applied with a sponge to ensure the animal is thoroughly wet. After application, the dog should not be rinsed or towel dried but either air dried or dried with a blow dryer. Normally, three to six treatments will be required to cure the dog. Take extra care when using these dips as they can be toxic.
- Weekly applications of lime sulphur for five or more weeks are safe and effective. However, be mindful as the product has a foul odor.
- Ivermectin and milbemycin oxime have been used by some veterinarians as an alternative treatment with reported success even without FDA approval.