Demodectic Mange Race Foster, DVM Drs. Foster & Smith, Inc.

Demodectic mange (also known as red mange, follicular mange, or puppy mange) is a skin disease, generally of young dogs, caused by the mite, Demodex canis. It may surprise you to know that demodectic mites of various species live on the bodies of virtually every adult dog and most human beings, without causing any harm or irritation. These small (0.25 mm) 'alligator-like' mites live inside of the hair follicles (i.e., the pore within the skin through which the hair shaft comes through), hence the name follicular mange. In humans, the mites usually are found in the skin, eyelids, and the creases of the nose. Disease related to suppressed immune system Whether or not Demodex causes harm to a dog depends on the animal's ability to keep the mite under control. Demodectic mange is not a disease of poorly kept or dirty kennels. It is generally a disease of young dogs that have inadequate or poorly developed immune systems or older dogs that are suffering from a depressed immune system. What is the life cycle of Demodex canis? The demodectic mite spends its entire life on the dog. Eggs are laid by a pregnant female, hatch, and then mature from larvae to nymphs to adults. The life cycle is believed to take 20-35 days. How is Demodex canis transmitted? The mites are transferred directly from the mother to the puppies within the first week of life. Transmission of the mites is by direct contact only. That is, the mother and puppy must be physically touching, as the parasite cannot survive off of the animal. This is important because it means the kennel or bedding area does not become contaminated, and therefore the environment need not be treated. Lesions, if present, usually appear first around the puppy's head, as this is the area most in contact with the mother. Virtually every mother carries and transfers mites to her puppies. Most puppies are immune to the mite's effects and display no clinical signs or lesions. A few are not immune and it is these that develop into full-blown cases of mange. What are the signs of demodectic mange? Individuals that are sensitive to the mange mites may develop a few (less than 5) isolated lesions (localized mange) or they may have generalized mange, in which case, there are more than 5 lesions involving the entire body or region of the body. Most lesions in either form develop after four months of age. The lesions and signs of demodectic mange usually involve hair loss, crusty, red skin and at times, a greasy or moist appearance. The mites prefer to live in the hair follicles, so in most cases, hair loss is the first noted sign. Usually, hair loss begins around the muzzle, eyes, and other areas on the head. In localized mange, a few circular crusty areas will be noted, most frequently around the muzzle. Most of these lesions will self heal as the puppies become older and develop their own [url=http://elkies.dogboard.net/javascript:popupWin1('/dictionary_term.cfm?term=immunity&cls=2', 50, 50, 350, 300)]immunity[/url]. Persistent lesions will need treatment that will be described later. In cases in which the whole body is involved (generalized mange), there will be areas of hair loss over the entire coat, including the head, neck, abdomen, legs, and feet. The skin along the head, side, and back will be crusty and oftentimes inflamed. It will often crack and ooze a clear fluid. Hair will be scant, but the skin itself will often be oily to the touch. Some animals can become quite ill and develop a fever, lose their appetite, and become lethargic. Patients with generalized demodectic mange need immediate vigorous treatment. How is demodectic mange diagnosed? Once Demodectic mange is suspected, it can usually be confirmed by a skin scraping or [url=http://elkies.dogboard.net/javascript:popupWin1('/dictionary_term.cfm?term=biopsy&cls=2', 50, 50, 350, 300)]biopsy[/url], in which case, the mites can be seen with the aid of a microscope. They are too small to be seen with the naked eye. The adults appear as tiny, alligator-like mites. Remember that these mites are present in every dog, so by themselves, they do not constitute a diagnosis of mange. The mite must be coupled with the lesions for a diagnosis of mange to be made. How is demodectic mange treated? The treatment of Demodectic mange is usually accomplished with lotions, dips, and shampoos. Fortunately, 90% of demodectic mange cases are localized, in which only a few small areas are involved and can often be treated topically. A treatment that has been successful for years has been a 1% rotenone ointment (Goodwinol ointment), or more recently, a 5% benzoyl peroxide gel applied daily. Bathing periodically with a benzoyl peroxide shampoo and feeding a high quality diet and a multivitamin with a fatty acid may also help some dogs. Most of these localized lesions will heal on their own and do not require overly aggressive treatment. If a dog develops generalized demodicosis more aggressive treatment is usually required. Studies show that between 30% and 50% of dogs that develop the generalized form will recover on their own without treatment, but treatment is still always recommended for the generalized form. The treatment of choice continues to be Amitraz dips applied every two weeks. Amitraz is an organophosphate, and is generally available under the product name Mitaban. It is a prescription product and should be applied with care. Humans should always wear rubber gloves when applying it to their dog, and it should be applied in an area with adequate ventilation. It is recommended that longhaired dogs be clipped short, so that the dip can make good contact with the skin. Prior to dipping, the dog should be bathed with a benzoyl peroxide shampoo to help remove oil and cellular debris. Most dogs with generalized demodicosis require between 4 and 14 dips. After the first three or four dips, a skin scraping should be performed to determine if the mites have been eliminated. Dips should continue until there have been no mites found on the skin scrapings taken after 2 successive treatments. Some dogs develop sedation or nausea when dipped, and toy breeds in particular are sensitive to amitraz. Half strength dips should be used on these sensitive animals. Ivermectin should not be used in Collies and similar breeds. Some dogs may not respond to this treatment, and the frequency of the dips may have to be increased or additional treatments may need to be instituted. Two other products, which though they are not licensed for the treatment of demodectic mange, are being widely used by veterinary dermatologists and general practitioners with some good results. One of these is ivermectin, which is the active ingredient in Heartgard, however, the concentration in Heartgard is not high enough to be effective against Demodex. Larger daily doses of liquid ivermectin must be given and should only be used under close veterinary supervision. Another drug, Milbemycin oxime (Interceptor), has also been given daily and been shown to be effective on up to 50% of the dogs that did not respond to Mitaban dips. Dogs that have generalized demodicosis often have underlying skin infections, so antibiotics are often given for the first several weeks of treatment. In addition, we usually recommend the dog be put on a good multivitamin/ fatty acid supplement. Because Demodex flourishes on dogs with a suppressed immune system, it is wise to check for underlying causes of immune system disease, particularly if the animal is older when they develop the condition. Prognosis and impact on breeding Demodectic mange is not an [url=http://elkies.dogboard.net/javascript:popupWin1('/dictionary_term.cfm?term=inherited&cls=2', 50, 50, 350, 300)]inherited[/url] condition, but the suppressed immune system that allows the puppy to be susceptible to the mites can be. Remember that all puppies receive the mites from their mother, but only a few have ineffective immune systems and develop the mange. This sensitivity can be passed genetically through generations. Individuals that have a history of demodectic mange, and their parents and siblings, should not be bred. Through careful breeding, most cases of generalized demodicosis could be eliminated. Can I get Demodex from my dog? The various species of Demodex mites tend to infest only one species of host animal, i.e., Demodex canis infests dogs, Demodex bovis infests cattle, and Demodex folliculorum infests humans. Conclusion In conclusion, a few important points should be repeated. The mites are transferred from the mother to offspring in the first few days of life. The first sign of hair loss usually does not occur until after four months of age. Demodectic mange is almost always curable or controllable with persistent treatment, except in rare cases with very immune suppressed individuals. The immune system condition that allows for the development of demodectic mange can be an inherited condition, and breeding of these animals should not occur. References and Further Reading Ackerman, L. Skin and Haircoat Problems in Dogs. Alpine Publications. Loveland, CO; 1994. Griffin, C; Kwochka, K; Macdonald, J. Current Veterinary Dermatology. Mosby Publications. Linn, MO; 1993. Scott, D; Miller, W. Griffin, C. Muller and Kirk's Small Animal Dermatology. W.B. Saunders Co. Philadelphia, PA; 1995.

(SOMETIMES CALLED
"RED MANGE" OR “DEMODICOSIS”)

THE CULPRIT - DEMODEX CANIS
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.

IS DEMODICOSIS CONTAGIOUS?
Demodectic mange (unlike Sarcoptic mange) is not contagious. 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 problems occur. Isolation of dogs with even the most severe demodicosis is felt to be unnecessary. While there is 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.
  

DEMODICOSIS HAS THREE FORMS

FORM #1: LOCALIZED
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.
  

Puppy with localized demodicosis around her left eye

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, 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.
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.

CAN THE PUP BE BRED LATER?
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 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.

Dog with generalized demodicosis

FORM #2: GENERALIZED
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 have inherently immature immune systems and are thus susceptible to the development of demodicosis without any sinister underlying diseases. As they grow up and their immune systems mature, they tend to naturally gain 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.

FORM #3: DEMODECTIC PODODERMATITIS
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 peis 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.

TREATMENT: STRESS AND GENERALIZED DEMODECTIC MANGE
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:

1. Females should be spayed as soon as the disease is controlled. Coming into heat, hormone fluxes, and pregnancy are very stressful. Also, predisposition to demodicosis is hereditary and should not be passed on.
   
2. The dog should be fed a reputable brand of dog food so as to avoid any nutritionally related problems.
   
3. Keep the pet parasite-free. Worms are irritants that the pet need not deal with and fleas may exacerbate the itchiness and skin infection.
   
4. Keep up the pet's vaccinations.
   
5. The mites themselves cause suppression of the immune system so the pet needs every advantage to stay healthy.
   
6. 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.