Demodex  

Sandra Merchant, DVM, Dipl. ACVD            

Carol S. Foil, DVM, Dipl. ACVD

                        

Demodectic Manage

Demodicosis (red mange) is a skin disease caused by a small mite not visible to the naked eye.  This mite lives down in the root of the hair.  All normal dogs have a small population of mites, but only certain animals will get a disease from mite overgrowth.  In some cases, the tendency to develop demodectic mange runs in families.

The disease is seen in TWO FORMS in the dog.  There is a localized form where only small areas of the skin are affected, and a generalized form where the majority of the body and/or the feet are involved.  Symptoms include loss of hair and reddening of the skin.  Affected areas may be scabby, crusty and sometimes itchy.  Skin infections due to damage by the mite are common.  Skin infections can become so severe that they threaten a dog's life, with ulcers, swelling and fever. Generalized demodicosis is a familial disease and affected dogs and their parents should not be bred. Diagnosis of demodectic mange is made by examining debris from deep skin scrapings under the microscope. Dogs with generalized disease also require further testing for underlying health problems.

 

Treatment of demodectic mange depends on the patient's age and the severity of the disease.  In the localized form, the dog may heal on its own.  Many times a cream or gel will be used to aid in healing.  It is important that dogs with the localized form be observed for a worsening of the condition or spread to other areas. Dogs that are intended for breeding should be observed without treatment to be sure the generalized form does not develop. Infrequently the topical medication may cause the affected areas to look worse before the areas begin to heal. If a skin infection is present, antibiotics will be needed.

 

Dogs with generalized demodicosis may require intensive treatment with amitraz (Mitaban®) dips or oral medications. If a skin infection is present, antibiotics will be needed.

 

MitabanR dip is the only FDA-approved drug for this disease. WHOLE BODY CLIPPING is required throughout treatment so that the dip solution can reach the mite down in the hair follicle.  Dips are usually preceded by a medicated shampoo to fight infection.   The MitabanR is packaged in individual dosing vials of concentrate which is diluted in water just prior to applying  to the patient.  Side affects of MitabanR can be encountered, especially in small dogs, including sedation, decrease in body temperature, loss of appetite, vomiting and diarrhea.  Treatment with an antidote, yohimbine, can be  used to decrease the severity of some side effects. Dips are usually applied either weekly or every two weeks according to the veterinarian's prescription.  We generally recommend that dips be applied by grooming technicians in the veterinarian's hospital.  
If no severe side affects are seen, treatment will be continues until repeated skin scrapes reveal no mange mites (typically 6-9 treatments) and for one more month after that.  Scrapings will be performed every 2-4 weeks to evaluate response to treatment. Occasionally, another form of amitraz (TakticR) is chosen because of lack of availability of MitabanR (but it is not an approved formulation). Different dilution instructions are required for TakticR.

 

Ivermectin or Milbemycin Treatment: Some dogs are very sensitive to amitraz and others do not respond even after many months of therapy.  For these dogs, veterinary dermatologists often turn to extra-label use of oral parasiticides that can be used for generalized demodicosis.  Ivermectin is available as a cattle worming agent (IvomecR and generics) and milbemycin is available as a heartworm preventive pill (InterceptorR) for dogs.  At very high daily dosages, these can be used to treat generalized demodicosis successfully in a majority of cases.

 

Note

Some Collies and other English breed herding dogs such as Australian shepherds, Border  collies, Shelties, and Old English Sheepdogs have a nervous system sensitivity ti high dose ivermectin and should not be treated with this drug except in unusual circumstances under the direct supervision of a veterinarian, who will build up to the needed dose very slowly. For mixed breed dogs of unknown lineage, the ivermectin rule is “White feet, Don’t treat!”

 

Neutering

It is a requirement of the VTH&C that all  generalized Demodicosis patients be neutered as soon as their disease is under control.  This is in the best interest for your dog since stress (breeding, heat cycles) can cause recurrence of the disease.  This policy is intended to reduce the incidence of this hereditary disease in pure bred dogs.

 

Animals with localized demodicosis have a good prognosis with proper care.  As the severity of the disease increases, the prognosis worsens.  Some dogs with generalized mange must have regular treatment for the rest of their lives while others may be cured after a variable number of months of treatment.

 

In all cases it is important to keep your pet as healthy and stress free as possible including a good nutritional diet, regular checkups, routine deworming and heartworm prevention.

 

Treatment For Your Pet

1) Amitraz therapy
Medicated shampoo ________________ to be used the day before the MitabanR dip is scheduled.  No bathing at any other time is allowed.

 

MitabanR dip: ____ in hospital; ____ at home.  Dip every ______ days.  Please make appointment for a drop-off for the day for in hospital dips.  If dipping at your home or your local veterinarian’s clinic, please make a recheck appointment at LSU after _____ dips.

 

DO NOT ALLOW YOUR DOG TO BECOME WET IN BETWEEN DIPPINGS.  Please call if any side affects from the dip are seen.

 

2) Ivermectin therapy

Give _____mls of liquid ivermectin (Ivomec®) by mouth once a day.  It may be mixed with soft food or a treat, but be sure the entire dose is ingested.  Skin scrapes are scheduled once a month in a drop-off morning appointment.  Please make a recheck appointment for skin scrapes on ______________________.  Ivermectin may cause neurological side effects in some dogs: wobbly gait, disorientation, change of personality, and occasionally vomiting.  If you see any of these problems, discontinue the drug and call us the next business day. You should discontinue using monthly heartworm medications throughout your dog’s ivermectin therapy for demodex.

 

3) Milbemycin therapy

Give _____ tablets (Interceptor®) daily with food.  These may be disguised in soft food or treats, but be sure the entire dose is ingested.   Skin scrapes are scheduled once a month in a drop-off morning appointment.  Please make a recheck appointment for skin scrapes on ______________________.

 

4) Antibiotics

Give ______ caps/tabs ______ times a day for ______ weeks.  Drug: _____________     Strength: __________   Please call for a refill or if any

side affects are seen.