(bad) news from france

hye evrybody one more time i have to ask you something aboute staffies cause here in france everything goes wrong... because all of you are from the staffie's original country i would like to know what you thik about that...
a couple of days ago somebody post a text on a french forum ( planete-staffie) about a blue staffie female who have a skin disease name Color Dilution Alopecia...for some reason a lot of this forum users start to say that this disease is a good reason to stop the blue staffie production in france and we need to sterilize all the blue staffies in france and also the black one with blue gene...they also suggest to stop to confirm any staffie blue or with the blue gene...
so what do think about that? i need to have your point of view
lena

Staffies are not the only breed to suffer from this and some of the breeds effected are dogs that are meant to be blue. Does this mean that entire breeds should be irradicated because of this. The problem lies in the fact that a blue dog of any breed is produce by a recessive gene and when doing so not only color genes are diluted but the genes for other things as well sometimes causing disorders when they do. Not always does the disorder happen but it is not uncommon. Personally I am not a real big fan of blue staffords... i like the color but have a problem with the blue to blue breeding generation after generation. The only true blue staffy for me is one that happens accidentally in a litter from black parents and very rarely do you see this conditio in such a dog as this.


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. 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.

The entire process of coloration and color patterns in dogs starts with embryonic development. The specific cells that become melanocytes (pigment producing cells) are derived entirely from the neuronal
crest of the embryo. This essentially means that pigment cells are directly produced along with the same cells that give rise to the nervous system. Though not entirely true, it can be assumed that if you have defects in genes associated with color genetics you might also have nervous system defects because both types of cells are derived from the neuronal crest. This provides a logical genetic indicator and explains why it is likely that certain dilute or patterned dogs, such as extreme piebalds, or other types of homozygous dilutes , as well as those that may be carrying the gene are prone to psychological, neurological and/or immunological problems found in other breeds that carry these alleles.

The allele like a couple other dilution factors when expressed in a homozygous state is correlated to psychological, neurological, and usually immunological issues. Here I will mention a few of the issues. The first are eye development problems that are superficial in nature affecting appearance such as heterochromia iridis (A difference of color between the iris of one eye and the other), thus a dog with one brown and one blue eye has heterochromia iridis. Note that this defect is not necessarily or always indicative of having the gene because it can also be found in dogs with extreme piebald or double blue
dilution for example. In addition to superficial indicators there are also major effects such as absence of tapetum lucidum. Tapetum lucidum is a reflective substance that lines the back of the dogs eyes. This reflective structure acts like a mirror and reflects light back through the retina, like a satellite dish giving the retina two chances to catch the light. Dogs that lack tapetum licidum have night blindness or reduced ability to see in low light. Another defect is lack of retinal pigment and microphthalmia. Microopthalmia (smaller than normal eye) is described as dogs having prominent third eyelids and seemingly small eyes which appear recessed in the eye socket (enophthalmos). Another problem known as coloboma is actually a physical cleft in a portion of the eye, particularly the iris . In addition to the eyes which are a key indicator of neurological defects, there is also evidence for effects on the ears that result in reduction in auditory sensitivity or complete deafness because the merle color locus exerts epistatic effects on ear development. Excessive white or dilution in a dog of any color can be a warning
sign of potential hearing problems. If there is no pigment in the inner ear the dog will be deaf; white ears are more likely to lack inner ear pigment.