Demodectic Mange (Demodex) is a parasitic skin disease caused by microscopic mites which affects millions of dogs each year. This informational site was created for puppy buyers, breeders, and owners of the American Pit Bull Terrier (APBT) and American Staffordshire Terrier (AST). This page is dedicated to Demodex in regards to the APBT and AST, with a few references to other breeds of dogs affected.
Table of Contents
- What is Demodectic Mange?
- Clinical Signs
- Localized
- Generalized
- Information about the Mite
- Diagnosis
- Treatment
- Causes
- Demodex can lead to Other Problems
- Breeding and Genetics
- Extreme Itchiness
- Links
Demodectic Mange (Demodex) is a parasitic skin disease caused by microscopic mites. Dogs have mites living on their bodies all the time (so do humans). Normally there is a balance between the parasites ability to reproduce and the host’s ability to kill the mites. A few mites live to keep the species going and the host never even knows it. Unfortunately, an occasional dog does not have the proper set of T-cells to kill the mites. This gives mites an advantage and they propagate excessively, over-running hair follicles all over the dog’s bodies. Since almost all dogs have Demodex mites somewhere on their body but only a few have clinical signs of Demodex the theory is that dogs don’t have to be infected with the organism because they probably already have it. The necessary key for disease to occur is immune suppression or immune incompetence. Demodex is most commonly seen in APBT & AST around the ages of 3 months to a year. It can occur later in life in dogs that have severe immune compromise for some reason. When it does occur in an older dog, a really good search should be made for some disease that could be causing it. The causative factors as to why some dogs develop demodex mange while other dogs do not is yet understood.
What is Demodectic Mange?
There are two forms of Demodex (addressed below), and clinical signs will depend on which type your dog has. Some Clinical signs are hair loss, inflammation of the skin, and in severe cases, pustules and itchiness with occasional bleeding. It is possible that ear infections or otitis could be symptoms of Demodex. A lot of clinical signs are actually due to a secondary bacterial infection. Some believe that Demodex has a distinctive “mousy” odor. Dogs with Demodex do not itch severely, even though it loses hair in patches. Areas of bare skin will be seen. The hair loss usually begins on the face, especially around the eyes.Clinical Signs
In localized Demodex there may be a roll played by stress or by some other factor that leads to suppression of the immune system. Most dogs with only one or two spots of localized Demodex will outgrow it as their immune system gets stronger with age or decrease in stress. It usually appears in dogs under 1 year of age. The first sign is a thinning of hair around the eyelids, the lips, and the corners of the mouth and the front legs. The dog has a moth-eaten appearance. The patches of hair loss can progress into circles of approximately one inch in diameter (occasionally confused with ringworm). Not all-young animals that experience Demodex are immunologically impaired for life. Significant percentages will self cure as their immune system matures. The maturity in APBT and AST normally takes place between ages of 8 months to 3 years, and this can vary depending on breed of dog. Localized Demodex occurs in less than 5 spots and 80% of dogs with localized Demodex will outgrow the condition. If an animal diagnosed with localized Demodex but is not improving and has 5 or more patches, could be progressing into the generalized form.Localized
Dogs affected by generalized Demodex have an immune deficiency that allows the skin to cause serious disease. In generalized Demodex there is a genetic defect that leads to an inability on the part of the dogs immune system to fight off this mite (in most cases). When a puppy does not outgrow the mange or when it spreads to several sites on the body it is most likely to be generalized Demodex and is therefore more likely to be an inherited condition thought to occur from a deficiency of a specific type of T-cell. The dogs that can not outgrow the problem can be difficult to treat but most of the time this mite can be controlled with persistent effort. Generalized Demodex can begin as a localized case or can present itself as a sudden onset. Dog suffers a breakout in 5 or 6 areas, sometimes covering the entire body. Numerous patches appear on the head, legs, and trunk. These patches continuously spread developing into large areas of hair loss. The hair follicles become congested with debris and mites. The breakdown of the skin leads to the formation of sores, with crusting and draining sinus tracts. Treatment of dogs experiencing generalized Demodex can be very prolonged. Response to treatment is slow and often requires frequent changes in the medication. In spite of the number of mite removal dips, topical ointments and antibiotics available a cure is not always possible. Generalized Demodex must be treated under veterinary supervision. Poor prognosis for mature dog can be fatal.Generalized
Information about the mite
Demodex mite looks like a worm or a cigar with 8 stubby legs on the anterior one third of the body. They are slender, whitish, and almost maggot like. Demodex mites can only be detected under a microscope. Adults are small .1 to .4 mm long (1/250 to 1/60 inch long). All dogs (and people for that matter) have the Demodex mite living in their hair follicles. The immune system controls the over growth of these mites. They have about an 18 to 24 day lifecycle. This means it is very hard for it to cause clinical disease in a puppy that is younger than about 8 weeks of age, because it takes a while for the population of mites to grow to sufficient numbers to cause the disease. The mites are in the class Arachnida (follicle mite) which is found worldwide. Larvae, Nymphs are similar to adults, but larvae are 6-legged. The mite’s entire life cycle is spent on the host. Females lay 20-24 eggs in the hair follicle. Larvae and nymphs are swept by the sebaceous flow to the mouth of the follicle, where they mature. Sites of infestation are hair follicles, and sebaceous glands. Host Spectrum includes Humans, rabbits, sheep, hamsters, cattle, swine, horses, goats, dogs, cats, and other mammals. Each affected by a different species in the Demodex genus. Development is gradual from metamorphosis, egg, 6-legged larva, protonymph, deutonymph, and finally adult. The Mite feeds entirely within the intradermal nodule, utilizing serum, sebum, and possibly white blood cells of the host. The infestation of the Demodex mite is year-round. Since almost all dogs already have these mites and since it takes very intimate contact to spread them from dog to dog, this problem is not considered to be a contagious disease. Demodex from dogs does not infect people-nor do Demodex mites from people infect dogs. They are passed from mother to puppies and are contagious in that sense but the disease occurs only in dogs in which an immune system deficiency allows the mite population to overgrow its normal boundaries and cause disease.
The Demodex mite can only be detected under a microscope and usually consists of a skin scraping or a punch biopsy. In some cases it is necessary to do skin biopsies to confirm mites when the skin damage has been chronic and severe. If bacterial infection is severe, blood tests and cultures of the pus may be necessary to determine the best antibiotic. The tests also show if there are other related problems, such as low thyroid function and anemia.Diagnosis
There are many ways to treat the breakout of Demodex. Some are proven others experimental but working. It is expensive to treat in some cases but usually it can be cured. Treatment needs to be based on skin scrapings, not just the appearance of the skin. A skin that looks like it is healed can still harbor Demodex mites. This is especially true for adult dogs with feet lesions. Treatment for localized usually will take 1 to 3 weeks, while generalized can take 2-3 months before it becomes effective. Localized Demodex will often clear up without any treatment at all, making almost any treatment appear successful at times.Treatment
* A soothing bath, such as oatmeal shampoos bath or a tar and sulfur shampoo bath might help with the itching. The generalized form requires shampoo therapy. Shampooing with a special cleansing shampoos helps to flush out the hair follicles prior to dipping. Some Recommendations for shampoos have been Oatmeal shampoo, Head and Shoulders, or a medicated antibacterial shampoo (called SulfaOxydex). Bathing with an antibacterial shampoo should be the first step in therapy. This loosens up scales, removes oily discharges, and decreases the secondary bacterial infection that is usually present.
* There is also a cream or ointment type treatment known as Goodwinol. This is generally used in dogs that have a localized breakout. It is usually very inexpensive and highly effective but must not be administered close to the eyes. Many vets do not feel that Goodwinol does much, so they usually tell people to wait and see if the spots disappear and do nothing. Lots of dog owners are not happy doing nothing, which is probably why Goodwinol continues to be recommended
* Mitaban Dip is the only approved medication for the treatment of Demodex. Dips are considered to be the oldest and most common, although somewhat of a high risk. Most dips used for the indication of curing Demodex contain the active ingredient Amitraz. Dips are usually very effective, somewhat costly, at around $45 per dip. Dips are required once a week. Dip requires some caution because it is a strong insecticide that can have some side effects to your dog, and to you if it is not used properly. Your dog may experience vomiting and sedation for 24 to 36 hours following each application. If so, those problems will usually be self-limiting. If this occurs, the dip should be diluted with 25% more water the next time it is used. Since each dipping result in the development of tolerance to the dip, your dog is less likely to have side effects with each subsequent treatment. Your dog should be dipped at least 3 times at 7 to 14 day intervals (without any baths in-between). After dipping is complete it is important to examine for the presence of live mites or mite eggs. Further treatment will be determined by the results. If you do the dipping yourself, be sure to wear rubber gloves to prevent getting it on your hands. Remember that it is usually a tech that will be dipping your dog, and not your veterinarian. Does the tech know what he/she is doing? Even some of the most experienced tech can accidentally get this into your dog’s eyes or mouth. Has the dip been properly diluted? A squirming puppy is more likely to get the dip in his or her eyes or mouth; this will cause severe sickness and can damage vital organ functions and in some cases even death. If you have not shaved the dogs prior to dipping with Mitaban you should consider doing this. It is supposed to work much better when the dogs are shaved prior to use. In a desperate situation veterinarians will sometimes dip the dog daily but only cover half of the body with the dip each day. It sometimes takes three or four dips with Mitaban to see a lot of improvement and it takes at least six or eight dips to cure the condition in most dogs. Works well, between 50-80% of the time to control generalized mange.
* Another treatment is the use of Mitaban mixed into olive oil. This mixture is applied on the areas of hair loss daily. Remember to keep away from the eyes and mouth.
* Ivomec is pure ivermectin as found in the monthly heart worm preventative Interceptor. This is usually given in the beginning as an injection once every three weeks. This is becoming a very common method of treatment and is gentle on your pocket book. This is a very safe way to treat your dog, proven your dog responds to this medication. Ivomec is administered either orally or by injection in high dosages. Vets will also consider the oral daily dosage of Ivomec if the breakout continues to worsen. This is a low dosage given orally every day for at least 30 days. Ivemectin is reasonably safe to use for Demodex and some dermatologists use it as a first choice product for this condition now. This use is considered to be experimental for dogs and there have been a number of suggested dosages, dosing intervals and duration’s of administration suggested for this medication. Your vet will probably have a dosing plan he or she is comfortable with. Side effects like excess salivation, in coordination; even coma and death are possible, so they must be used judiciously. They should not be given to Collies, Shelties, Australian shepherds, or dogs that are positive for heartworm.
* A new treatment out for Demodex is very costly but said to also be very effective. It consists of giving your dog a single Interceptor (or milbemycin) a heartworm preventative medication tablet every day for 90 days.
* Antibiotics are good idea when there is significant inflammation and infection around the feet or other areas affected by Demodex. This is also considered to be an experimental use in dogs. In general antibiotics will control the itching within a few days as it is usually from the presence of a bacterial skin infection. Continuous long-term antibiotic usage may be beneficial even when the mites can not be eliminated. Antibiotic therapy for secondary infections is very important in the success of therapy for Demodex.
* Pain Relief medications are often prescribed. It is important to be sure that there isn’t an existing problem that they might worsen (especially liver disease) but even in that case it is usually possible to use at least one of the available pain relief medications. Would you want to walk on feet that look like your dog’s feet look without pain relievers?
* Antihistamines help a few dogs.
* Aspirin is even helpful in some cases.
* Thyroid problems are common in dogs with Demodex. There for it usually does not hurt to supplement thyroid hormone.
* Motor Oil is not safe to use on pets. That is usually the oil recommended by home remedy enthusiasts. It is better now than it was when cars burned leaded gas, but it still can cause gastrointestinal problems.
* It is usually not considered to be a good idea to use cortisone’s in a dog with Demodex because they suppress the immune response to the mites even further than it is naturally suppressed in dogs susceptible to this problem. My also effect the resistance to treatment. It is usually considered to be OK to use corticosteroids to control the intense itching when treating for sarcoptic mange, which is a completely different problem that Demodex. Prednisone (a corticosteroid) helps dogs to reduce itching, if necessary. But it is not recommended for dogs that have been diagnosed with Demodex that may be generalized. Often, corticosteroids make it possible for the Demodex mites to really cause problems but if this happens they should be easy to find on skin scrapings.
Demodex can return after an apparent cure. Lots of dogs do not ever have completely negative skin scrapings for this mite but it can be well managed. It is important to know that these dogs are always subject to a flare-up of the Demodex if they are sufficiently stressed. If the immune system is defective, neither the mites nor the infection may respond to treatment. Due to the fact that the immune system is paramount in whether or not your pet gets this disease, no guarantee can be made that these medications will work. No matter which form of Demodex is treated, several issues need to be addressed. Your pet needs to be on optimum nutrition stay current on vaccines, and free of internal parasites (worms). Like of any disease process, the psychological needs of your pet need to be met, which includes plenty of exercise, TLC, and access to fresh water at all times. Other skin conditions like allergies can occur simultaneously, and need to be treated also.
*The immune system is able to control the overgrowth of these mites. When the immune system is weakened by illness, or naturally weak it allows the Demodex mite to grow and overpopulate. There are tests that can be run to determine factors that might contribute to a weak immune system. Testing of White Blood Cell count (WBC) and Red Blood Cell count (RBC) can always give you an insight into your dog’s immune system. There are probably other tests as well; something good to run once a year is a general health profile. This is a great test for insight into your dog’s immune system. It just consists of drawing about 1cc-2ccs of blood, the blood is then spun down and the serum on top removed, this is what is used for the testing, this test will check function such as liver, etc. When a bitch goes into heat, her immune system is weakened; this is one reason why some bitches have Demodex only when in heat.Causes
* It is possible to get Demodex from stress or major stresses such as cancers. Stress is often a misunderstood term. APBT and AST are usually a high stress breed. We tend to think of stress as a bad thing and assume that it must have a cause. This isn’t necessarily true. There can be good stresses if you don’t think so, think back to your wedding day! Stress can be anything that makes your dog’s body react to hormonal influences, good or bad. It is very hard to determine what might worry a dog or what might make a dog happy enough to cause good stress. Despite this, it is unknown how much stress really has to do with Demodex in many cases. The stress of the heat cycle is also thought to cause Demodex to worsen.
* It is believed to be possible to get Demodex from, bad nourishment or unsanitary environment.
* Hyperadrenocorticism
* Liver disease seems to be able to predispose dogs to Demodex, and is also more common in older dogs.
* Cancers are possible underlying causes of the occurrence of Demodex in an older dog.
* Food allergies
* Cushing’s disease is the most notable cause of a relapse of Demodex, but this is present primarily in older dogs.
* Chronic use of cortisone
* Heartworm
* Hypothyroidism
* Diseases such as diabetes can also impact therapy.
* Usually you will not see much worsening of the disease due to surgery. It is possible that surgery could induce enough stress to make the Demodex infestation worse but this is rarely seen. It is not necessary to wait for an infection to clear up before spaying.
Stress and poor health can do a number on the immune system. Certain conditions can bring on relapses or new occurrences of Demodex. It is important to know that this all results in a weak immune system. In many cases it is impossible to eliminate the underlying cause. Any condition causing sufficient immunosuppression can lead to problems with Demodex so it is always a good idea to look carefully for an underlying cause, especially in a older dog suddenly showing signs of Demodex infestation. There are underlying causes that can weaken the immune system and make a pet more susceptible to this disease. Demodex is often mistaken for Skin infection, fungal illness, and systemic disease with skin manifestations.
Since dogs with Demodex have a weak immune system this can attract a number of other diseases or problems. A few common ones are Distemper, Parvo, Bordetella (Kennel Cough), Leptospirosis, continuous upper respiratory infections (URI), and many more. Even if your dog has been vaccinated, as in humans a weakened immune system allows your dog to be susceptible to these diseases. It is even believed that vaccinated puppies do not develop anti-bodies. It also is not unusually for dogs to test low on thyroid hormone when they have significant illness of any type, so this may be misleading lab value in some cases. Staphylococcus infection with a strong sour odor is usually followed by a Demodex break out.Demodex can cause other problems
Although nothing solid has been proven, many vets believe this to be a genetic condition due to a weak immune system. Many owners and breeders feel that this condition can only be passed down from the mother to the offspring. This is a misconception. Sires as well as well as dams are able to pass this weakness into offspring. In the recent past owners were routinely counseled by veterinarians to spay or neuter any dog affected with either form of Demodex, any dog can break with the localized form and need not necessarily be removed from a well-conceived breeding program. Certainly, those dogs affected with the generalized form should be spayed or neutered.Breeding and Genetics
Vets will tell you that they believe it to be ok to breed dogs that have suffered a localized break out of Demodex, as long as the breakout was a one-time deal. It is important to know if the dog will outgrow this condition on its own if you intend to breed it. If you have a potential/future-breeding animal that has Demodex, do not dip. Alter diet to optimum, use Vitamin E supplement, treat secondary staph infection, make sure pup or dog is current on vaccinations, intestinal parasite free and in the best possible health. Let the dog’s immune system rid itself of the mite. If the dog does outgrow it then it is probably not genetic in origin and it is has been considered OK to breed. If the condition is not treated and resolves on its own, that is a good sign that an inherited immunodeficiency is not present. If it does not clear on its own then the animal should not be used as a breeding stock. Wait out these cases with great patience to see if Demodex will self-cure. If two dogs have Demodex that was locally only and they recovered fully from it, without treatment, than they’re probably isn’t an increased likelihood of generalized Demodex in the puppies. Many Vets will and should recommend spaying and neutering dogs that have suffered a generalized breakout of Demodex. Being the immune system in that animal is severely weak and therefor can be passed down to his or her offspring. It is also recommended to Spay or Neuter dogs that continually whelp pups with generalized Demodex even if they have never had Demodex. Some breeders believe that if these dogs were removed from the gene pool the number of cases in our breed would deplete and eventually would be gone. Though many people feel that if they treat it and it never comes back it is ok to breed. Some also believed that Demodex is from close inbreeding. It is tough to make a decision to spay a good bitch or to neuter the sire, or both, when generalized Demodex appears in a small percentage of puppies in a litter.
There is no way to prove that Demodex is occurring due to an inherited tendency in an individual dog, or to disprove this. In some breeds Demodex is pretty well established but in other breeds there is more of a question mark. The breeds known to have a tendency to develop Demodex include the APBT, AST, shar pei, West Highland White Terrier, Scottish Terrier, English Bulldog, Boston Terrier, Great Dane, Weimaraner, Airedale, Malamute and Afghan. In the end, the decision on breeding or not breeding is up to the breeder. Many dog breeders have an entirely different outlook on this situation.
Demodex mange by itself is not an itchy skin disease, but itching may result because of skin infection and related irritation. A secondary bacterial infection, which should be at least partially controllable with antibiotics, is common in dogs affected with Demodex. There are exceptions to every rule. Dogs with extreme Itchiness should be switched to a hypoallergenic diet, such as the new one Purina has come out with, Hill’s I/d, one of the Innovative Diets foods or a homemade diet suggested by your veterinarian. It may be a food allergy that is contributing to the problem, by removing the offending food it my produce a significant reduction in clinical signs in two to four weeks, or possibly slightly longer. Another alternative is to ask for referral to a veterinary dermatologist. For dogs with extreme itchiness is recommended to use hot spot itch relief spray, hot spot shampoo, hot spot pads, food supplement, or a new diet.Extreme Itchiness
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Facts and information in this web page came from Books, Web Sites, and Magazine articles on Demodex. I would like to thank Sandy Comer (Lar-San Kennels), Elaine (Nitro Kennels), and Dr Paul Burton (Benicia Veterinary Hospitial) for helping me in gathering information regarding this disease.
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