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DEMODEX IN THE DOG

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Demodex in the dog is a common infestation of the dog’s skin with
tiny, cigar-shaped, eight-legged mites. Human demodex cases do
occur but transmission from the dog to a human is quite rare. The
mites reside and feed in the hair follicle and oil glands of the skin.
Also called Mange, which is a general term used to describe any
kind of mite infestation, Demodex is generally less severe than
Sarcoptic mites (often called scabies).



Fortunately, most cases of Demodectic mites are self-limiting…
that is, the animal is able to arrest the reproduction and growth of
the mites and eventually repair the damage they do. Once
eliminated, most dogs do not acquire another infestation; the dog’s
immune defenses are primed to eliminate any new Demodex
mites that happen to find themselves on the dog. However, there
are certain individual dogs that, because of genetic programming,
do not produce the specific immune factors that will target the
mites for destruction. That specific lack of adequate immune
defense against the mites is a hereditary aspect of the disease that
can predispose an infested dog to a severe, unresponsive case of
Demodex. Many veterinarians believe that all dogs have small
numbers of Demodex mites residing in the skin and that having a
few mites is normal and common. It is when immune related, or
nutritional or environmental stresses impact the dog that visible
skin lesions from mite infestations become noticeable. Seen most
commonly in young dogs, and rarely in cats, Demodex skin lesions
are usually transient, but occasionally in certain individuals the
mites will totally overwhelm the dog's skin. .




QUESTION: Can Demodex mites be inherited?
ANSWER: No. The mites are not present on the fetus while the
fetus is developing from an embryo in the uterus. However, if the
mother has demodex mites present in/on her skin, the mites can
invade the new fetus' immediately after birth. Since all dogs have
Demodex mites present in their skin, and never actually develop
noticeable skin lesians, the mother might not even be showing
signs of mites and yet tranfer mites to her newborn pups. The pups
may or may not develop a case of mites.

QUESTION: Why, then, do I keep hearing that Demodex can be
inherited.
ANSWER: The problem is the wording. The specific antibodies that
will defend against infestation of Demodex can be inherited and
most dogs have those immune factors and are able to defend
against Demodex. But some individuals have inherited a deficiency
of those antibodies and just don't have the ability to fend off the
mites. So the ability to resist the mites, or not resist, is inherited.
The actual mites are not inherited.

QUESTION: So if I have a pup that has Demodex and it is only six
weeks old and has never been in contact with any dogs outside our
home, the mites must have come from the mother. But, the mother
has never had Demodex so how could this happen?
ANSWER: Your assumption that the mother dog has "never had"
Demodex is probably not valid. Demodex mites have been proven
to inhabit the hair follicles of many, many dogs, humans and other
mammals without causing the host any problems at all. So these
mites can be present in normal and healthy individuals (who have
inherited the immune factors needed to keep the mites
suppressed). So just because you have not experienced a visible
skin lesion on your dog does not mean that the dog has no mites
present.

QUESTION: If I have a dog that has Demodex, does that mean I
should not breed it?
ANSWER: If the dog, male or female, has a protracted, difficult-to-
cure case of Demodex, that dog should not be bred. If you have a
dog that has or had a brief, localized episode of Demodex and has
recovered well, then breeding may be considered; but some
veterinarians believe that any dog that has displayed skin
manifestations of Demodex should be removed from a high quality
breeding program.

QUESTION: Is Demodex transmissible to my healthy dog from a
dog that is infested?
ANSWER: Healthy dogs are quite resistant to infestations and, as
mentioned, may already have a number of mites residing
harmlessly in the skin. It is best, though, to not allow your dog to
have direct physical contact with a dog that has an active case of
Demodex... just to be safe

QUESTION: What about the dog that suddenly develops Demodex
later in life and never had it as a puppy?
ANSWER: This is called Adult-onset Demodicosis and is most
commonly seen in what are assumed to be healthy dogs but that in
reality are actually affected with an underlying pathology or immune
compromising disorder. Therefore, whenever a veterinarian is
presented with a case of Demodex in an adult dog the doctor is
alerted to the possibility that there is a potentially serious
underlying disease going on that has compromised the dog's
immune integrity. Such afflictions as cancer, Hypothyroidism,
Systemic Fungal Disease, adrenal gland diseases and even
exposure to prescribed cortisone medications can allow previously
innocuous resident mites to reproduce rapidly and cause visible
skin disease. Adult-onset demodicosis is not a genetically
programmed disorder. These cases can be difficult to cure unless
the underlying stressor is resolved successfully.

DIAGNOSIS

Demodex mites usually create irregularly shaped, mildly irritated
areas of hair loss. The skin is usually not inflamed and the lesions
are not highly pruritic (itchy). Conversely, Sarcoptic mite lesions are
very pruritic, inflamed and scabs may be present.

The diagnosis is made by doing a skin scraping of the affected
area and placing the scrapings on a microscope slide. Click here
to see how a skin scraping is done. Usually the material scraped
from the skin is mixed with mineral oil and then examined under
the microscope. (NOTE: Sarcoptic mites are rarely visible via skin
scrapings and are therefore very commonly misdiagnosed as an
allergic skin disorder because the veterinarian "couldn't see any
mites". See this article for important information about Sarcoptic
Mites.) Demodex mites are plentiful and seem to be easily detected
via skin scrapings even though they spend most of their time deep
in the hair follicles.

TREATMENT

In dogs with very mild, localized, small skin lesions some
veterinarians do not treat the dog at all. Other veterinarians will
always treat Demodex lesians with topical medication appropriate
as an insecticide. (Some home remedies are harmful so always
consult with your veterinarian about any kind of skin lesion and the
safest and most effective therapy.) These organisms are live
parasites so applying such remedies as Vitamin E cream or aloe
vera will have no effect on them.

It is vitally important that all dog be consuming a high quality, meat-
based diet with proper amounts of high quality fat. Any dog,
especially a growing pup, that is consuming a cheap, grain-based
diet will not fare as well as the dog eating a high quality diet. In
general, the better diets are higher in price so do not let your
decision about what to feed your dog be dictated by the cost. The
nutritional aspects of skin disorders is an often overlooked
"treatment" and should always be considered when a health
impacting situation is present. For good information about nutrition,
visit this department for a list of articles.

Mitaban was a commonly used treatment for Demodex and had a
proven record of successes. This prescription-only product is
diluted with water and applied to the dog's skin according to the
product directions. Repeated applications are almost always
required. This product may no longer be available. On occasion a
veterinarian may decide to use a product called Ivermectin. This
product must be very carefully calculated regarding dosages that
are effective and not toxic. The use of Ivermectin in treating
Demodex needs to be discussed with the owner prior to use since
it has not been labeled for use against Demodex. Another
treatment that is sometimes used is oral milbemycin given daily for
six to eight weeks. Lime-Sulphur dips have been used in the past
and some veterinarians continue to prefer this therapy for
demodex. Ivermectin in fairly high doses is also used... with
owner's consent and with caution!