"RED MANGE" OR “DEMODICOSIS”)
Demodectic mange, also called "demodicosis," is caused by a microscopic mite of the Demodex genus. Three species of Demodex mites have been identified in dogs: Demodex canis, Demodex gatoi, and Demodex injai. The most common mite of demodectic mange is Demodex canis. All dogs raised normally by their mothers possess this mite as mites are transferred from mother to pup via cuddling during the first few days of life. Most dogs live in harmony with their mites, never suffering any consequences from being parasitized. If, however, conditions change to upset the natural equilibrium (such as some kind of suppression of the dog's immune system), the Demodex mites may "gain the upper hand." The mites proliferate and can cause serious skin disease.
(original graphic by marvistavet.com)
Demodectic mange (unlike Sarcoptic mange) is not considered a contagious disease and isolation of affected dogs is generally not considered necessary. That said, there are some circumstances under which the mites could spread from one dog to another. Classically Demodex mites have been felt to only be transferable from mother to newborn pup. After the pup is a week or so old, it has developed enough immunity so that infection is no longer possible. In other words, after age one week or so, a dog will not longer accept new mites on its body. Recently this idea has been challenged as occasionally multiple unrelated dogs break with demodicosis in the same household. It is not clear if some species of Demodex are more contagious than others or if some contagion is possible under certain circumstances. Current thinking is that mites actually can be transferred from one dog to another but as long as the dog is healthy, the mites simply add into the dog's natural mite population and no skin disease results. In rare circumstances contagion is possible if a very severe infection is involved. While there are still assorted theories about dog to dog transmission of Demodex mites, there is no question that mites cannot be transmitted to humans or to cats.
- Mites live inside hair follicles -- a difficult place for miticides (chemicals that kill mites) to reach.
- Mites are a normal residents of dog skin; it is only in some individual dogs that mites cause problems.
Localized demodicosis occurs as isolated scaly bald patches, usually on the dog's face, creating a polka-dot appearance. Localized demodicosis is considered a common puppyhood ailment and approximately 90% of cases resolve with no treatment of any kind. This is quite a contrast to generalized demodicosis as described below so it is important to be able to distinguish localized from generalized disease. It seems like this would be a simple task since localized demodicosis classically involves several round facial bald spots and generalized demodicosis involves a bald scaly entire dog; still, reality does not always fit into neat categories in this way. Some guidelines used to distinguish localized demodicosis include:
- Localized disease does not involve more than two body regions. (One spot or two on the face and one spot or two on a leg would still qualify as localized even though the spots are not close together.)
- Localized disease involves no more than 4 spots total on the dog.
Treatment is not necessary or recommended for localized demodicosis but there are treatment options for people who simply cannot feel right about doing nothing. Goodwinol ointment, an insecticide ointment, may be used daily to control localized demodicosis. Antibacterial gels are also used against localized demodicosis and associated skin infections. It is important to note that rubbing a creme or ointment on a demodicosis lesion can cause reddening of the lesion making it appear to get worse. It is also possible for rubbing the medication on the area to break off the weaker hairs at the margin of the lesion causing the lesion to appear to get bigger. Neither of these situations truly represents exacerbation of the disease.
Puppy with localized demodicosis
around her left eye
(original graphic by marvistavet.com)
Resolution of a localized demodicosis lesion should be at least partially apparent after one month though total resolution can take up to three months.
Approximately 10% of localized demodicosis cases will progress to generalized demodicosis. Enlarged lymph nodes are a bad sign -- often foretelling generalized mange.
Sometimes the puppy with localized demodicosis was obtained for breeding purposes. The current recommendation is not to treat these puppies so that we can determine if the condition will stay localized and resolve or if it will generalize. If it stays localized and eventually resolves without treatment, the animal is still a candidate for breeding. If the condition generalizes to cover the entire body, the animal should be sterilized. If the condition receives treatment and resolves, we will never know how the disease would have gone in its natural state and will not know whether the pup is carrying the genetic predisposition for generalized demodectic mange. In this case, it is best to be conservative and not take the chance of passing on genetic predisposition for this disease.
Localized demodicosis is almost exclusively a "puppyhood" disease. When a puppy develops localized demodicosis the chance of the condition resolving is 90% unless there is a family history of demodicosis in related dogs. In this case, chance of spontaneous resolution drops to 50%.
Occasionally an adult dog develops localized demodicosis. We currently do not have good understanding of the prognosis or significance of this condition in an adult dog.
Classically with generalized demodicosis, the entire dog is affected with patchy fur, skin infections, bald, scaly skin. Sometimes large patches of affected skin are present, sometimes multiple "polka dots" of lesions cover the dog, and sometimes the entire body is involved. The secondary bacterial infections make this a very itchy and often smelly skin disease. The approach to generalized demodicosis typically depends on the age at which the dog developed the disease.
ADULT ONSET-- Most demodicosis occurs in young dogs, under age one and a half. An older dog should not get demodicosis unless he or she has an underlying problem with the immune system. In such cases, demodicosis is considered a indication to seek a more serious hidden condition such as cancer, liver or kidney disease, or an immune-suppressive hormone imbalance. A more extensive medical work-up will be required.
JUVENILE ONSET -- Young dogs that develop demodicosis are believed to have a genetic immunological defect that allows the mite to gain the upper hand. As the puppy grows up and his or her immune system matures, the immune system tend to naturally regain control of their mite infestation; in fact, 30-50% of dogs under age 1 year recover spontaneously from generalized demodicosis without any form of treatment. Usually treatment is recommended, though, to facilitate recovery.
IT IS VERY IMPORTANT THAT DOGS WITH A HISTORY OF GENERALIZED
DEMODECTIC MANGE NOT BE BRED AS THERE IS A HEREDITARY
COMPONENT TO THE DEVELOPMENT OF THE DISEASE.
This condition represents demodectic mange confined to the paws. Bacterial infectious usually accompany this condition. Often as generalized demodicosis is treated, the foot is the last stronghold of the mite. Old English Sheepdogs and Shar pei tend to get severe forms of this condition. The infection can be so deep that biopsy is needed to find the mites and make the diagnosis. It is one of the most resistant forms of demodicosis and the deep infections and proliferative tissue that result can take months and great expense to resolve.
The treatment of demodicosis only in part relies on medications; some basic steps can be taken with regard to pet care to maximize the chance of success. Physiological stress is an important factor determining the degree of severity of demodectic mange and the following steps should be taken to reduce stress:
- Females should be spayed as soon as the disease is controlled. Coming into heat, hormone fluxes, and pregnancy are very stressful and will encourage the mites. Also, predisposition to demodicosis is hereditary and should not be passed on.
- The dog should be fed a reputable brand of dog food so as to avoid any nutritionally related problems.
- Keep the pet parasite-free. Worms are irritants that the pet need not deal with and fleas may exacerbate the itchiness and skin infection.
- Keep up the pet's vaccinations.
- The mites themselves cause suppression of the immune system so the pet needs every advantage to stay healthy.
- Skin infections are usually present in these cases and antibiotics will likely be necessary. It is very important that cortisone type medications such as prednisone NOT be used in these cases as they will tip the immune balance in favor of the mite.
CURRENT TREATMENT OF CHOICE -- IVERMECTIN
Ivermectin is a broad spectrum anti-parasite medication with a number of uses though its use in treating demodicosis is not approved by the FDA. Before ivermectin was available, the only treatment for demodicosis was dipping (see below) which is labor intensive and not without side effects. The advent of ivermectin has changed the prognosis of demodicosis entirely. Ivermecint is inexpensive and easy to give by mouth or as injection. Daily or every other day dosing is usually necessary and most patients achieve cure or at least control of their disease. (Note that the weekly ivermectin protocols that work for other parasites do not work on Demodex mites.)
That said, there is an important caveat: Some individual dogs, those with the MDR1 mutation, are sensitive to ivermectin and can die if subjected to a typical therapeutic dose for demodicosis. In most cases, ivermectin-sensitive dogs are members of the collie-family, Old English Sheepdogs or other herding breeds.
THIS MEDICATION CANNOT BE ASSUMED SAFE FOR
USEIN COLLIES, SHETLAND SHEEPDOGS, AUSTRALIAN SHEPHERDS,
OLD ENGLISH SHEEPDOGS AND, SOME WOULD SAY, ANY HERDING BREED.
So if there is any question about a dog's heritage, what you should be done to be sure treatment is safe? One way to go is to use a test dose for several days prior to starting the therapeutic dose. A better way is to actually test the dog for the MDR1 mutation since we now have that ability thanks to Washington State University.
For details on testing for ivermectin sensitivity visit:
There is a range of ivermectin doses used in the treatment of demodicosis and it seems that higher doses do clear infection faster than lower doses. This means that if a lower dose has been ineffective, a higher dose may still work. This does not mean that a pet owner should experiment with ivermectin doses on their own as there is some potential for lethal toxicity if this drug is not used appropriately.
The doses of ivermectin used in the treatment of demodicosis are not compatible with the commonly used flea product spinosad (Comfortis® or Trifexis®). The combination of spinosad and high doses of ivermectin will increase the likelihood of ivermectin neurologic side effects. While flea control is very important during the treatment of demodectic mange, a different product should be used.
Another important caveat concerns heartworm. The high doses of ivermectin needed to kill Demodex mites will rapidly kill circulating larval heartworms in a heartworm infected dog. The sudden death of a large number of worms in the bloodstream can lead to shock so it is important to verify that the patient is heartworm negative in dogs that are old enough that heartworm infection is possible. Heartworm requires a good 6-7 months to establish an infection so younger puppies are not at risk for this reaction.
For more information on Ivermectin, click here.
MILBEMYCIN OXIME (SENTINEL®, MILBEMAX®)
Milbemycin oxime is a macrocyclic lactone like ivermectin and it seems to be just as effective as ivermectin in treating demodicosis. Even better, it has a much broader safety margin with MDR1 mutation dogs. Milbemycin oxime was originally introduced to the small animal market as a heartworm product called Interceptor® which has since been discontinued. Tablets came in a 6 pack and were intended for monthly use. Treatment of demodicosis requires daily use, however, and that made the product often prohibitively expensive. Today, Interceptor® is no longer available but milbemycin oxime can be obtained in combination with other dewormers so at least it remains an option.
If the demodicosis patient is a member of a breed suspicious for the MDR1 mutation, it is still recommended to test for the mutation before giving large doses of milbemycin oxime. As with ivermectin, milbemycin oxime will rapidly kill heartworm larvae and potentially lead to shock so it is important to test dogs that are old enough to have a heartworm infection prior to use.
MOXIDECTIN (ADVANTAGE MULTI®)
Moxidectin is another microcyclic lactone that could be used in the treatment of demodicosis (though probably not in ivermectin sensitive animals). In Advantage Multi®, moxidectin is administered topically once a month as a dewormer and heartworm preventive to provide broad spectrum parasite control in combination with imidocloprid for flea protection. Moxidectin has activity against demodex mites and is often effective if used weekly in the treatment of demodectic mange. Results have not been as reliable as those with ivermectin particularly in more severely affected dogs or older dogs.
Prior to the introduction of ivermectin, amitraz dipping was the mainstay off demodicosis treatment. Today it is mostly for the MDR1 mutation dogs that amitraz dips continue to be used. Dips are smelly, not without toxicity, and pose a great deal of work.
Unless the animal is largely bald or has a short coat, complete clipping will be required for maximal contact with the dip..
Dip should be preceded by a benzoyl peroxide bath to help clear up skin infections and open the hair follicles so the dip can penetrate to the mites. Shampoo must sit on the pet at least 10 minutes before rinsing. CAUTION: this type of shampoo can stain jewelry and clothing.
Dip is applied by sponge. Gloves should be worn while applying dip. The dip dries on the dog's fur and should not be rinsed off. The dog should not get wet between dips.
Dipping occasionally yields mild sedation as a side effect. Very small dogs may become highly sedated and require an antidote but this is unusual. For your convenience, dipping and bathing may be performed at the hospital thus allowing for veterinary supervision in the event of side effects.
Dipping/bathing is recommended every two weeks according to the FDA approved label on the bottle of dip. Most universities are finding that the cure rate jumps from 25% to 80% when dip is used at double strength and applied weekly. No toxic effects have been seen using the dip in this way and this is our current recommendation when opting for dips except in very small dogs and puppies.
Dipping is a fair alternative for ivermectin in collie breeds and in ivermectin sensitive individuals.
AMITRAZ DIPPING SHOULD NOT BE USED IN TOY BREEDS
OR IN YOUNG (UNDER 4 MONTHS OF AGE) PUPPIES.
NOTE: Amitraz is a drug of the monoamine oxidase inhibitor class. People who are taking selected serotonin reuptake inhibitors (such as fluoxetine) could have a bad reaction to the use of amitraz if they administer dips to pets. Similarly, pets on SSRI's may have reactions to amitraz. Human diabetics should also avoid administering amitraz dips as amitraz may interfere with glucose regulation; diabetic pets may have trouble as well.
Promeris® is/was a prescription topical flea and tick product also labeled for the control of demodicosis. Its anti-tick active ingredient is amitraz (the same active ingredient in Mitaban® dip described above). The product is typically used every 2-4 weeks to treat demodicosis and has the advantage of being safe for the collie-type breeds (and other individuals with ivermectin sensitivity). Promeris was withdrawn from the market by Pfizer in 2011 because of immune-mediated reactions emerging with regular use for flea and tick control. Still, some product may still be around and in use so we mention it here.
The younger the dog, the better the chance of cure. Most dogs under one year and a half years of age, recover completely from generalized demodicosis. In many cases of adult-onset demodicosis, the disease is controlled with treatment but cure is not always possible. Some cases can never be controlled.
Treatment, no matter which option is chosen, should be accompanied by skin scrapes every 2-4 weeks. In this way the effectiveness of treatment is assessed and modifications of dosing can be made. There are several protocols published describing how to determine if treatment can be stopped. The idea is to eradicate every single mite from the dog's body so that the condition cannot recur. This typically entails either continuing treatment for a significant time after the patient appears recovered and/or rechecking skin scrapes a significant time after treatment has finished.
When relapse occurs it is often because the dog appeared to be normal and the owner did not return for the appropriate re-scrapings. Relapse is always a possibility with generalized demodicosis as there is no easy way to confirm that every mite has been killed but most dogs that relapse do so within a 6-12 month period from the time they appear to have achieved cure.
SARCOPTIC MANGE IS A COMPLETELY DIFFERENT DISEASE.
Click here for information on Sarcoptic mange.
(original graphic by marvistavet.com)
In older times, decades ago before there were effective medications, dipping dogs with demodectic mange in motor oil was a popular home remedy. Skin exposure to motor oil can cause rashes and skin destruction in severe cases. The hydrocarbons can be absorbed through the skin and cause a dangerous drop in blood pressure. If motor oil is licked off the coat, resultant vomiting can lead to aspiration of motor oil into the lungs and pneumonia. Kidney and liver damage can result from motor oil dipping.
PLEASE: DO NOT DIP YOUR DOG IN MOTOR OIL!
Page last updated: 9/6/2015