|Demodectic Mange In Your Dog
How Did My Pet Catch Demodectic Mange?
Most veterinarians believe that Demodex canis is found in most or all dogs in low numbers that cause no disease. We also believe that puppies probably become contaminated with these mites shortly after birth as they nurse and snuggle with their mother who already harbors the mites. However, studies done in 2009 in Italy may challenge that conclusion.
That leaves us asking why some dogs develop demodectic mange and some do not. We know that the juvenile form of demodectic mange often cures itself after a period of a month or so. This is probably due to your pet’s immune system responding to the parasites and killing them. Age-related immunity is known to neutralize a number of other parasites and this probably occurs with Demodex as well.
However, certain pets and certain breeds have problems controlling the mites. In these pets, the number of demodectic mites becomes very large, resulting in skin inflammation (mange). As common as this problem is in dogs, it is unfortunate how little we really understand about its basic cause.
What Signs Will I See If My Pet Has Demodectic Mange
Localized Demodectic Mange
The first are young dogs that are not yet mature. Owners often notice a small patch of thin or missing hair on the pet’s face, but also occasionally on the leg or trunk. It is rare for these little patches to be inflamed or itchy. These patches are quite distinctive – similar to the one in my illustration. Ninety percent of these localized cases will resolve in a month or two with or without treatment. But in approximately ten percent, the mites are not eliminated and go on to colonize much of the pet’s skin. Those pets have developed generalized demodectic mange.
Generalized Demodectic Mange
The second group of dogs have generalized mange that involves many areas of the body. These dogs have sparse or patchy hair coats. Their skin is often overly pigmented and thickened. These pets have a musty, unhealthy odor. Many have waxy ear infections (ceruminous otitis).
Some of pets with demodectic mange itch and scratch. When they do, they usually have a secondary bacterial skin infection that needs treatment. The superficial lymph nodes on these pets are often enlarged. They may run a low fever and appear listless and ill.
Occasionally, generalized demodectic mange will occur in an older pet that had no previous problems with the mites. Pets that develop demodectic mange later in life generally have a weakened immune system due to another chronic heath problem. This can be a hormone imbalance such as an overly active adrenal gland, diabetes, liver or kidney failure, an immunosuppressive tumor or the use of medications that suppress your pet’s ability to keep mite numbers under control. Corticosteroid medications, such as prednisone, have been known to trigger Demodex, as has the generalized debility of heartworms.
When a dog over two years old suddenly develops demodectic mange, a series of tests will be necessary to try to locate its underlying problem.
The localized, spontaneously curing, form of demodectic mange does occasionally occur in older dogs. But it is quite uncommon.
Occasionally, dogs develop demodectic mange that is confined to their feet and paws. When this occurs, the paws become puffy, malodorous and raw due to secondary bacterial infection. These cases can be very stubborn and resistant to treatment.
Are There Other Problems That Can Be Confused With Demodectic Mange?
Other medical conditions that cause inflammation of the hair follicles have signs very similar to demodectic mange. They include food allergies, staphylococcal hypersensitivities, skin fungal and yeast infections, and long-standing cases of sarcoptic mange. A skin scraping that is positive for Demodex mites, confirms the diagnosis of demodectic mange. If no mites are found , your veterinarian will tests for these other possible causes of chronic skin disease.
How Will My Veterinarian Determine If Demodectic Mange Is My Pet’s Problem?
When your veterinarian is suspicious that your pet might be suffering from demodectic mange, the vet will often scrap these lesions with a scalpel blade and a drop of oil to confirm that mites are present. Scotch Tape, pressed against your pet’s skin, and then examined under the microscope may also detect the mites.
If the lesion is confined to a sensitive area of the face, microscopic examination of the roots of plucked hairs is often sufficient to find the parasite. When the pet’s ear canals are the only areas affected, Q-tip swabs can be the sample source.
When secondary skin disease is severe, or when mange has been present for long periods, the mites can be hard to locate. In these cases, skin biopsies often locate them.
Treatments That Cure Demodectic Mange?
Dogs With Localized, Isolated Demodex Lesions:
Young dogs with no more than four isolated small patches of mites generally get better without treatment. However, when the number of patches continue to increase in number or size, it is wise to administer medications.
Rotenone-containing creams and spot treatments with amitraz-containing formulas are often sufficient to eliminate localized demodectic lesions. In species other than dogs, Tea Tree Oil (melaleuca) has been effective. Do not attempt to use these products without veterinary supervision.
Dogs With Generalized Demodectic Mange;
Demodectic mange can be a very stubborn problem. It can take many months of effort to cure it. When medications do not fully cure your pet, failure to eliminate the mites is usually due to generalized poor health that needs attention, stopping treatment too soon or steroid administration.
Pets weakened by Demodex may need nutritional support, a low stress environment, antibiotics and topical antibacterial and antifungal medications to help clear the mites from their skin.
If your pet is slow to respond, your veterinarian my switch medications to see if better results can be obtained with a different medication.
A macrocyclic lactone or avermectin, this is the same compound that is found in many of the once-a-month heartworm preventative tablets. However, it must be used more frequently (every 1-2 days) and at larger doses to kill demodectic mites. The medication can be given orally or by injection.
Avermectin - sensitive dogs can be identified through a blood test.
Since compounds in this group quickly kill heartworm larva in the blood, pets need to be confirmed heartworm-negative before beginning treatment.
Dogs receiving ivermectin for mange should not be receiving spinosad-containing medications (Comfortis) during the same period.
Amitraz (Mitaban) Dip
This was the “old standby” treatment for demodectic mange. It is still used. The compound is sold as a dip. For it to work, the active ingredient must come in direct contact with the mites. This requires that the pet’s hair coat be clipped and its skin cleaned with shampoos before each application. The smelly dip must be massaged into the pet’s skin while it is partially submerged in the solution (protective ointments are used to protect the pet’s eyes). Specific instructions and cautions are provided with the bottle. These dips are generally done at veterinary hospitals at 7-14-day intervals. I do not suggest you use this product at home.
The solution often ends up on the owner or applicator. It is smelly, stains and can have a number of negative health effects on both the owner and pet. These side effects are more frequent in small breeds, puppies and debilitated pets. Please do not get this material on your body or inhale it.
Dips are continued until no living mites are found on skin scrapings. When Amitraz does not cure dogs at the manufacturer’s FDA-suggested dose, veterinarians sometimes resort to increasing the dip concentration or frequency.
A relatively new flea/tick control product also contains amitraz (ProMeris). Some veterinarians have used this product to control or eliminate demodectic mange. It is a much more "user friendly" form of amitraz for dogs that do not tollerate the avermectins.
Dogs with demodectic mange are predisposed to bacterial skin infections that make mange cures more difficult. When your vet suspects that bacteria have taken advantage of your pet’s unhealthy skin, the vet will put your pet on antibiotics in addition to the medication used to kill the mites. These antibiotics do not kill demodectic mites – but they make the chances of curing your pet much better.
The bacteria that colonize the skin of dogs with demodex are often staphylococcus. When they get deeper into the pet’s skin than they should, they cause infections called pyodermas. These bacteria can be eliminated or controlled with antibiotics that are known to kill staph. Bactericidal shampoos also help control these bacteria.
Can My Other Pets Or People Catch Demodectic Mange?
Cross-transfer between semi-mature and mature pets appears to be very unlikely in demodectic mange. But there have been rare instances where more than one unrelated pet in a family developed demodectic mange. We do not understand why this occurred. Perhaps some strains and species of demodectic mites are more pathogenic than others.
THIS ARTICLE IS ONLY A GUIDELINE