Mange is a parasitic skin disease
caused by microscopic mites. Two different mange mites cause skin disease
in dogs. One (the Demodex mite) resides in the hair follicles, while the other
(the Sarcoptic mite) lives just under the surface of the skin.
Although both mites share some similar characteristics, there are some important
differences. It is important not to confuse the two types of mange because
they have different causes, treatments and prognoses.
There are other types of mite which infect dogs, but these are not true
mange mites, and not discussed here. They include the fur mite, Cheyletiella
("creeping dandruff"), Otodectes, the ear mite, and the harvest mite Trombicula.
Sarcoptic Mange or Scabies
The presence of the sarcoptic mite causes severe itching which often looks
like severe eczema. The dog will chew and scratch its skin constantly. This
leads to a loss of large amounts of hair.
Sarcoptes often starts first on the ears and legs, particularly the elbows
and hocks, but can rapidly spread over the the legs, shoulders, ears and under
the abdomen, and on to cover the whole body in severe cases. Eventually the
skin will become thickened and will darken due to pigmentation, and often
look rather elephantine. Affected skin in active areas can seep rancid smelling
serum which often becomes secondarily infected with bacteria and fungi.
Sarcoptic mange is highly contagious to other dogs. It is also contagious
to humans. The dogs bedding should be discarded or, if this is not possible,
it should be washed and then sprayed with a veterinary insecticide. Your veterinary
surgeon will advise you and supply the correct one to use. Although the mites
are not able to complete their life cycle on people, they will burrow into
the skin and cause quite a lot of itching before they finally die.
In the Downland Veterinary Group area a lot of cases are the result of contact
with the heavily infected local fox population. Cases are also common in kennel
situations, particularly racing greyhound kennels where there is frequent
interchange and mixing of dogs from a large number of different backgrounds.
Diagnosis
Diagnosis is not always easy as the disease looks very much like allergic
eczema. Skin scrapings are performed and examined under the microscope for
mites or mite eggs. However, if only a small number of mites may be present
on the dog, skin scrapings may be negative. A presumptive diagnosis is then
made because the signs are suspicious. Treatment is then commenced without
the confirmation of a skin scraping. Age is not a significant factor in sarcoptic
mange, although it seems more common in puppies. It will affect all ages of
dogs.
Treatment
Treatment is with a specific mange wash and is normally done at 1-2 weekly
intervals. Two treatments may be all that is required, although sometimes
treatment will continue for several months. There are a number of products
available, some of which are of dubious value. Always discuss the treatment
with your veterinary surgeon to ascertain the best and safest product to use
in your situation.
Should bathing not prove effective, injections with a preparation called
ivermectin may be successful. This product is not licensed for use in dogs
and the implications of this must be discussed with your veterinary surgeon
prior to its use. It cannot be used in Border Collies or similar breeds. If
bacterial infection is also present, antibiotics will be prescribed. A spray
for the house and bedding will also be needed and your veterinary surgeon
will provide you with this.
Inn cases where there is secondary infection, antibiotics and other ancillary
treatments may be required.
If any member of the family develops an itching skin rash, it will usually
clear once the dogs are treated. If you are at all concerned, it would be
wise to see your doctor. In people, the mite cannot complete its life cycle
so it will die in a few days. Reinfestation from the dog or premises can result
in continued itching.
Demodectic Mange
Demodectic mange is sometimes just called Demodex. It is caused by the Demodex
mange mite, a parasite which lives in the hair follicles of affected dogs.
Under the microscope, this mite appears shaped like an alligator with eight
legs. All dogs (and many humans) have a few of these mites on their skin.
As long as the body's immune system is functioning, these mites cause no harm.
Demodectic mange most often occurs when the dog has an immature immune system,
allowing the mites to grow rapidly. Therefore, this disease occurs primarily
in dogs aged less than 18 months. In most cases as the dog matures, the immune
system also matures. Adult dogs that have the disease usually have defective
immune systems.
Since the mite is found on virtually all dogs, exposure of a normal healthy
dog to one with demodectic mange is not dangerous.
Development of the immune system is under genetic control. Thus, an affected
dog usually comes from a litter containing other affected puppies. Owners
of littermates should be put on alert to watch for it. If the disease is widespread
over the body it may be due to a genetic defect and affected dogs should
not be used for breeding. Also, parents of the affected dogs should not be
bred from again.
Although any breed can be affected the Bull Terrier breeds seem to make
up a large proportion of the dogs which are seen with clinical Demodex.
Sometimes the disease can occur as a result of treatment of the dog with
immunosuppressant drugs including corticosteroids.
Signs of the disease
Surprisingly, a dog with demodectic mange does not itch severely, even though
it looses hair in patches. Areas of bare skin will be seen. The hair loss
usually begins on the face, especially around the eyes. When there are only
a few patches of hair loss, it is termed localised demodectic mange. If the
disease spreads to many areas of the skin, it becomes generalised demodectic
mange. It may become itchy if the skin becomes infected with bacteria or yeasts.
We can check for these if necessary.
Diagnosis
The presenting signs will usually arouse your veterinary surgeon's suspicions.
Diagnosis is made in most cases by the laboratory examination of skin scrapings
as is Sarcoptes. As the mite can get 2-3mm below the skin surface in the follicles,
deep scrapings are necessary. Sometimes it may be necessary to take a skin
biopsy to confirm infection.
Treatment
The localised form is usually treated with topical medication and clears
easily. The generalised form may require more intensive treatment.
Shampooing with a follicular flusher to open the hair follicles (roots).
An example of these shampoos is Etiderm or Paxcutol. The dog is thoroughly
dried afterwards.
Wash with an anti-Demodex shampoo. We prefer Aludex solution. It is important
that the solution is diluted according to instructions on the bottle and scrubbed
into all of the skin. It is essential for you to wear gloves while applying
the solution. The wash contains the insecticide Amitraz. The product can
have side effects on the dog and you if not used properly. Most dogs will
appear sleepy for a few hours after the bath.
These two treatments are repeated every 5-7 days until the mites are eliminated.
This can take anywhere from weeks to several months. We will keep a regular
check on you and your dog and advise you when to stop. After the treatment
it will be necessary to examine your dog for the presence of live mites or
eggs.
Vitamin E can be taken as tablets or capsules and helps stimulate the immune
system.
Antibiotics. For dogs with generalised demodectic mange, secondary skin
infections may represent a complicating factor requiring antibiotic therapy.
Dogs with skin infections have very red, inflamed itchy skin. This is the
source of the term "red mange".
As Sarcoptic infections, your veterinary surgeon may suggest the use of
ivomectin in the treatment of severe or intractable cases. We must again
emphasise that this is not a drug licensed for use in the dog and should
only be used after full discussion with your vet. It is, however, sometimes
necessary to use products such as these since the risk surrounding their
use is less than the risk of untreated demodectic mange.
Prognosis
Treatment of the localised form is generally successful. Treatment of the
generalised form is also usually successful, but takes time and perseverance.
However if the immune system is defective, neither the mites or the skin infection
may respond to treatment.
Because the immune system does not mature until 12-18 months of age, a dog
with demodectic mange may have relapses until that age. It is important for
treatment to begin promptly to minimise the possibility of developing uncontrollable
problems. demodectic mange may also occur in very old dogs because function
of the immune system often declines with age. Dogs who have immune suppression
due to illness or medication are also candidates for the development of demodectic
mange.
and Finally
Demodectic mange can be one of the most frustrating conditions to treat
in the dog. In young animals it can keep returning until the immune system
is mature enough to keep the mites in check. It is important that you and
your veterinary surgeon work together to help keep it under control and ultimately
to cure it. We as a profession only want the best in treatment for your dog,
and are fully aware that the time involved in the treatment of mange can be
frustrating for all involved (including the dog!!). To this end, please keep
your appointments and follow up treatments as requested, and if you are frustrated
let us know!
The above information is simply informational. It's intent is
not to replace the advice of a veterinarian nor to assist you in making a
diagnosis of your pet. Please consult with your own veterinarian for confirmation
of any diagnosis. Your pets life may depend on it.
