written by R.M. (Bug )
Russell
The dilute colors (fawn and blue) do have coat and
skin problems and there is a ton of available information on them. There is
one major problem called CDA (see below) that is an alopecia (hair loss)
directly related to the coat color. The granules of material which provide the
color of the coat are located in the hair shaft...in blacks and most reds and
fawns and blue who don't have CDA the material is evenly spread through the
hair shaft. In the CDA dogs it is found in clumps...the clumping evidently
makes the hair shaft fragile at that point and prone to breaking. When this
happens below the skin line in the follicle itself it can "kill" the follicle
so no new hair is produced. That's the abbreviated version of the major
problem.
Dobes in general are rather prone to staph infections...their immune systems
are rather slow to mature...in a black and most reds this may be a problem in
puppies and may result in temporary hair loss but in blues and fawns it can be
a disaster coupled with CDA.
The rarity of seeing these colors in the ring is due in part to the
difficulties in keeping them in good coat. Barbara Russell, who sort of
specialized in dilutes, specifically blues, had blue Dobermans that generally had
good coats she states that
was that even with good blue coats she had problems and keeping blues in show
condition as far as coats went was a full time job.
There are definitely some judges who aren't fond of the dilutes and a few that
wouldn't put one up under any circumstances. In the '60s it was harder for
reds to win than blacks...I think that is about where the dilute situation in
the ring is now...it's harder to win with a dilute but not impossible if the
dog is a good specimen of a Doberman.
The dilute colors are produced much less often than reds or blacks. Genetic
statistics say that fawns comprise about 6% of all Dobermans born and blues
somewhere between 12 & 15%...all the rest are black or red but I can't
remember what the stats are for them).
Thin coats on the dilute colors are not usually due to allergies and the
dilutes don't seem to have any more skin problems, with the exception of CDA,
than blacks or reds do.
If the coat looks good from 2 or 3 feet away it probably is good but most
puppies in dilute colors have decent enough coats the thinning due to CDA
takes place over time so a dog who had a decent coat at 10 months might well
be bald at 5 years.
The dermatology texts say that over 90% of all blues will at least have
thinning hair and many will thin to the point of being bald over most of the
body. Fawns seem to have a better chance of retaining their coats with about
75% of the fawns having extensive hair loss due to CDA.
The literature also says that the darker the coat color in a dilute dog (steel
blue in blues and caramel in fawns) the better the chance they will retain most
to all of their coats. This seems to be the case in the blues and fawns I've
known over the years.
There are a few dilute dogs whose coats are fine, who don't lose hair, don't
have CDA and never go bald but they are few and far between.
COLOR DILUTION ALOPECIA
By Teri Dickinson, DVM
Alopecia (hair loss) related to dilute coat
color is a recognized condition in dogs. The currently accepted medical
terminology for this condition is Color Dilution Alopecia (CDA). The condition
may affect any dilutely pigmented dog, regardless of coat color. This
condition was previously known as Blue Balding Syndrome, Blue Doberman
Syndrome, Color Mutant Alopecia, Congenital Alopecia, etc. The term Color
Mutant Alopecia arose because dilutes were at one time mutations from the deep
pigment occurring in wild canines. Dilutes are now a regularly occurring form
of pigmentation in many breeds and have been for hundreds of years. The term
mutation is therefore not applicable to dilute individuals. References to
Doberman Pinschers or blue hair coats arose because the condition is common in
blue individuals of this breed, but it is not limited to either blue dogs or
Dobermans. The term congenital means present at birth, but CDA affected dogs
are born with normal hair coats.
The dilute (also known as Maltese) gene also
appears in both mice and cats, and interestingly enough, is not associated
with any abnormal coat conditions in those species.(1) Color Dilution Alopecia
(CDA) has been recognized in dilute individuals of many breeds of dogs
including Chow Chows, Dachshunds, Doberman Pinschers, Great Danes, Irish
Setters, Italian Greyhounds, Standard Poodles, Salukis, Whippets, and
Yorkshire Terriers.((2),(3),(4),(5)) Dilute individuals carry a recessive
genotype of dd and are characterized by blue, bluish-grey, lavender or flesh-colored
noses, lips and eye rims. The coat colors may include blue, fawn, blue-fawn,
bronze, taupe or some variation of these. These dogs are usually easily
distinguished from their deeply (non-dilute) pigmented counterparts. Deeply
pigmented individuals carry a dominant genotype of Dd or DD and have black or
liver noses, lips and eye rims. Coat colors may include black, red, red-fawn,
liver or variations thereof.
CDA is characterized by loss of hair from
dilutely pigmented areas. Coats are normal at birth, and
onset of hair loss usually begins between six months and three years of age.
Hair loss usually begins along the dorsal midline (middle of the back) and
often spares the head, tail and limbs. The pattern seems to vary from breed to
breed. It has been suggested(6) that darker colored (steel blue) individuals
are less likely to be affected, may be less severely affected or may start to
lose hair later in life than lighter colored dogs. This suggests that the
severity of the disease may be related to the amount of dilution present.
Deeply pigmented or white areas of coat are unaffected. In blue dogs with tan
points (Yorkies and Dobermans) the tan areas retain a normal appearance. In
piebald (white spotted) individuals, the white areas are unaffected by the
hair loss. The hair loss may be total or partial and any remaining hairs are
usually sparse, rough and easily broken or removed. The skin in the affected
areas is usually scaly and may occasionally develop bacterial infections.
Pruritus (itching) is usually absent, unless a bacterial infection has set in.
Diagnosis of CDA requires first ruling out
other causes of hair loss. Diagnostic tests should include
fungal cultures, skin scrapings to check for parasitic mites, etc. CDA often
closely resembles
endocrine (hormone related) hair loss and the dog should be carefully examined
for any other
abnormalities, and tested for normal thyroid function. Presence of dilute
pigment and a characteristic course of disease also aid in making the
diagnosis. Microscopic examination of hairs and\or skin biopsies can be used
to confirm the diagnosis.
There is no cure for CDA. Treatment is limited
to controlling the scaliness and any associated pruritus with various shampoos
or topical treatments.
The cause of CDA is not clearly understood.
Microscopic examination of hairs of dilute individuals
reveals that the pigment (melanin) forms large granules (macromelanosomes)
which are rarely found in deeply pigmented hairs. In dilute individuals with
normal appearing coats, these macromelanosomes are not grouped or clumped and
cause no distortion of the cuticle (outer covering) of the hair. Dogs with CDA
have many large groups or clumps of macromelanosomes which tend to distort the
cuticle of the hair. It is hypothesized that this distortion of the cuticle
causes the hairs to break easily, resulting in the short stubby hairs commonly
found in affected individuals. (See Drawing). It is further hypothesized that
the rupture of the hair releases byproducts of pigment formation, which are
toxic to the hair follicles. Regrowth of broken hairs is reduced because of
damage to the follicles caused by
these toxins.
Why in some dilute dogs the macromelanosomes
are clumped and in others they are not, is an
interesting question at this time. The relationship between dilute pigment and
hair loss is clear, but
why are some dilute individuals unaffected? Weimeraners as a breed are dd, all
individuals are dilute, yet the disease is unreported in this breed. In
Dobermans, the dilute individuals comprise only 8-9% of the breed, yet 50-80%6
of the dilute dogs have CDA. In Italian Greyhounds, many individuals are
dilutes, yet the IGCA health survey reported only 71 affected individuals
among the approximately 2200 dogs included in the survey.(7) If half the dogs
included in the survey were dilutes, the incidence of CDA in IG's would be
around 7% of the dilute population, as opposed to the 50-80% affected dilute
Dobermans.