Demodex -- Red Mange
Demodectic mange (Demodecosis) is caused by an external parasite that is present in low numbers on healthy animals, including people. Whether or not a pet shows symptoms of this disease depends primarily on their immune status. Since there is no easy test to determine immune status, it is impossible to predict which pets will get this disease or how well a pet will respond to treatment if it shows symptoms of demodex.
It is important to note that the diagnosis of this skin condition, like most skin conditions, cannot be made just by looking at a pet. Stating that an animal looks "mangy" is not the same thing as making a positive diagnosis of mange. Pets that have Ringworm or Sarcoptic mange can look like they have demodex. Pets with lots of fleas can have hair loss that also looks like mange. Diagnostic tests are mandatory to arrive at a correct diagnosis so the animal can be treated correctly.
Demodectic mange is caused by a mite, a microscopic ectoparasite that infects the hair follicles. Most pups pick up these mites from their mother when they are nursing. On healthy pups with good immune systems, they cause no problems. The immune system keeps their numbers small so they cannot cause disease. Pets that have inadequate immune systems develop demodecosis, or more commonly called, mange.
The parasite is cigar shaped and has several pairs of legs. The mite lives down in the hair follicles and kills the hair shaft. The mite is microscopic and is only visible with the aid of a microscope.
One of the most common symptoms of this disease is hair loss (alopecia). The hair loss is commonly first noticed around the eyes. Eventually, the hair will be lost from the entire body.
If a pet has only a few small patches of hair loss, the disease is classified as localized (local to only a few spots). If it has spread all over the body it is classified as generalized. Demodex is most commonly seen in young animals but adults can get it also.
Localized with only hair loss around the eyes.
Generalized demodecosis on the chest and front legs.
The primary way to diagnose demodectic mange is to do a skin scraping where there is hair loss. A skin scrape is performed by pinching the skin to force the mites out of the hair follicles and up to the skin surface. A scalpel blade is then used to scrape the skin surface in order to pick up the mites. The scraped material is then put on a microscope slide with oil and viewed under the microscope. In most cases the mites are easy to find under the microscope and your veterinarian can show them to you. This is a positive diagnoses for demodectic mange and will require treatment.
We are fortunate to have several medications at our disposal
to treat demodecosis. The most commonly used was
Mitaban. It has been discontinued but there is an
alternative
that works great -
AMITRAZ. This medication is highly
effective, and have saved many pets from suffering, and even euthanasia.
Most dogs are cleared of demodex after six dips but some dogs require dips all their lives, once monthly, to keep the mites killed off. Some dogs may have allergies associated with the poor immune system or even develop a deficient thyroid gland. Unfortunately, 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.
Sometimes the most we can hope for is to control the problem, not cure it. Treatment duration needs to 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.
No matter which form of demodex is treated, your pet must be healthy in all aspects in order to clear the disease. Simply dipping the dog will not cure demodex.
Ancillary treatment includes:
1. Deworming with a good dewormer such as Drontal.
2. Treat underlying skin infections with antibiotics.
3. Itching must be controlled with antihistamines so the pet will quit scratching.
4. Thyroid supplementation may be needed if it is determined the pet is hypothyroid.
5. Underlying allergies appear and need to be treated.
Localized Treatment
Bathing with an antibacterial shampoo is the first step in therapy. This loosens up scales, removes oily discharges, and decreases the secondary bacterial infection that is usually present.
Localized demodex can be treated with a medication called Goodwinol. It is a creme that is rubbed into and around the areas of hair loss. This rubbing initially causes more hair to fall out, but within 1-3 weeks the problem usually goes away. If more areas of alopecia appear during this time they should be treated with Goodwinol and brought to the attention of your vet.
It is possible for localized demodex to progress to generalized demodex even if it is treated. Rarely, localized demodex might resolve without any treatment.
Generalized Treatment
Generalized demodex is treated with a combination of medications and modalities.
Treatment failure is most common when the prescribed drugs are not given and the pet is not dipped every week for 6 consecutive weeks. If you miss a week, you are back to square one and have to start dipping and treatment all over.
If Amitraz does not work there are other medications that are used with varying success to cure the problem. None of these usually works as well as Amitraz. These include oral Ivermectin and Milbemycin (Interceptor). Side effects like excess salivation, lack of 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. There can be no guarantee that they will work, especially in a disease that is so closely associated with the immune system.
Prevention
The only prevention is to spay and neuter all pets with this problem.
