Educational post

[Gina Heitz <brier@oregonsbest.com>]

Hi All,

Auntie Ellen has come through with some articles she has written and have
been published in both the Harrier Club of America news letter and the
Willamette Beagle Club news.  This first one is about Demodectic
Mange some times called Demodex.  Now don't go flipping the big one
if your puppy at 6 months or so has a occurrence of demodex.  While
we have not had but one case in any related dogs a Sprite /Runner boy who
is now 2 1/2 and fine, it can happen but is usually as Ellen points out a
localized condition which usually will spontaneously go away.  Good
info to file away.  Yukon the dog that was affected was an intact
male and came up with one patch on his face at about 11 months of
age.  

We would never knowingly breed a dog who has been affected by this to a
degree that this paper implies to be reason for non breeding.  This
is not something we "clear for" but certainly consider as
important as anything else.   Compromised immune systems should
not be bred.  However we know that not every one has these
standards...

We do know of a breeder here in Candy Or. Diana Cheadle Foxburrow who has
produced several dogs from the same parents diffrent litters that
unfortunately have been plagued with the generalized form of this. 
These poor puppies have suffered as well as their families.  


Gina



Demodectic Mange

Demodex mites are a normal inhabitant on the skin of dogs.  They
live in the hair follicles and sometimes in the sebaceous glands. 
Puppies are born without the mites, however they will be transferred to
the pups from the dam in the first few days of life.  However, the
mites are not considered to be contagious to normal healthy adult
dogs.  Thus, demodectic mange is most likely due to a dysfunction of
the dog, not due to an increase in virulence of the mite. 
Demodectic mange occurs when, for some reason, the mites have a surge in
population.  There are two types of demodicosis, localized and
generalized.  

Localized demodicosis is the most common form.  It is most often
found in dogs less than 1 year of age.  There is no breed or sex
predilection.  Small lesions are usually found on the head and
extremities.  The lesions appear as small areas of hair loss, with
varying degrees of redness, scales, infection and itchiness.  It is
often diagnosed by taking skin scrapings of the affected areas and
examining the debris microscopically.  If mites are detected, then
the diagnosis is often confirmed.  However, because the mite is a
normal inhabitant, it is best to find more than one or two mites on a
slide to be positive.  Generalized demodex is essentially the same
as localized, however, large areas of the skin are affected. 
Typically, you will also see scaling, crusting, redness and
infection.

There are predisposing causes for either form of demodicosis. 
Recent incidents of stress or trauma, such as poor nutrition, separation
anxiety, estrus (heat cycles), pregnancy, or other stressful periods can
deplete the dog’s immune system.  Underlying diseases that stress
the immune system can also affect the dog’s ability to naturally control
the mite.  The use of immunosuppressive drugs such as steroids or
antineoplastic drugs can also induce localized or generalized demodectic
mange.  Finally, there does seem to be a genetic predisposition for
this disease.

Localized demodex is most often a self-limiting condition, especially in
dogs less than 12 months of age.  The usual treatment is to attempt
to identify and remove the predisposing causes and then allow the body to
heal itself.  Spontaneous remission will usually occur within a few
months.  There are topical agents available for treatment, but are
often not necessary, given enough time.

Generalized demodex is a much more difficult condition to treat. 
Cure rates are only about 50%.  However, in many dogs, the mite
population can be adequately controlled so that the dog is
asymptomatic.  Sadly, there are some cases that are not treatable
and may result in euthanasia.  There are several different types of
treatments available.  Amitraz dips are the most commonly used, with
the protocol of how often to be determined by your veterinarian. 
There are some side effects that can occur to the dog, such as sedation
and gastrointestinal disturbances.  A newer treatment protocol is
based on research done by Drs William Miller and Danny Scott and Cornell
University.  While this protocol is not yet approved by the FDA, and
the study not long enough to draw accurate conclusions about long term
cure rates, it is promising to be fairly effective.  It involves
using the drug Interceptor, which is a heartworm preventative, on
a daily basis.  The precise mechanism of action of the drug on the
mite is unknown.  If you have a dog with this condition, discuss
this possibility with your veterinarian.  Also, ask your vet to
inquire with the manufacturer about making a deal to reduce the cost, as
at normal pricing, this is a very expensive treatment.  The
manufacturer may have short-dated product available that they may be able
to offer at a substantially reduced price.  The only known side
effect of this treatment is ataxia (weakness), which occurred in toy dogs
and went away as soon as treatment was stopped.

There is no sure way to prevent this disease other than avoiding
predisposing factors and removing any dogs with the generalized form from
breeding programs.  It is generally considered okay if a young dog
has a mild, localized case as a puppy.  However, if the localized
form does not go into remission spontaneously or the dog gets repeated
episodes, especially as an adult, those dogs should also be removed from
a breeding program.

There are other forms of mange caused by different mites which are
contagious to other dogs and sometimes to people, so it is important to
have skin lesions checked if there is no known cause.  It is also
important to treat any underlying conditions or conditions that result
from the demodicosis, such as skin infections.