*Posting some info that may be found helpful :) Please do lots of research if ever questioning a topic, health issue etc. Especially if considering breeding which will affect not only the puppies but their future families. The dogs cant chose responsibly so it is our job as pet owners/breeders to be the responsible party to do the reading, research and testing as well as prevent accidental breedings. (Regarding a breeding of a chocolate to a yellow lab - which I always have been completely against however it is not impossible! But genetic/DNA testing is required to be sure you will not produce dudley puppies. ) * Does the Dudley/pink nose only occur when the >chocolate gene (b) occurs in a double dose? No. Dudley/pink is a condition in which there is complete absence of pigment in the skin and should not be confused with fading of pigment (which I describe below). Dudley/pink is an extremely rare condition in Labs and would occur due to presence of a homozygous (i.e. double) recessive allele of the C locus [most likely c(d)]. You would see this condition occurring in a Lab whose coat color is yellow, but the presence of a homozygous c(d) would cause the yellow coat to appear as a true white. This allele would have no impact on black or chocolate/liver expression because alleles of the C locus only affect phaeomelanin (red/yellow pigment) which is produced by the recessive e of the E locus (yellows are homozygous e [i.e. ee] at the E locus. >And the liver/brown colored nose snow nose >only when the chocolate gene (b) occurs in >a single dose along with a gene for Black? > >And the black nose, black eyeliner occurs >only when the Black gene occurs in a double >dose (BB). Its a bit more complex than this, and it is important to understand that snow nose and the liver/brown colored nose are not the same. First, the B locus alleles will determine whether a Lab has black or liver (aka chocolate) pigment. To have chocolate pigment, a Lab must be homozygous recessive b at the B locus (i.e. bb). The Lab will have black pigment if it is homozygous or heterozygous for B (i.e. BB or Bb). The liver/brown nose, however, is different than what is referred to as snow-nose. Liver/brown (aka chocolate) is dilution of black at the melanosome level and occurs when the dog is homozygous (double) recessive b at the black locus. A yellow lab can have a liver/brown nose (as well as eye rims) if it is homozygous b at the B locus...but this is not snow nose because it is not due to fading and such a yellow Lab will always be liver/brown pigmented and will never show black pigmentation. Snow-nose is a different condition entirely in which a yellow dog can produce black pigment at one time or another, but this pigment is susceptible to fading based on environmental conditions. Fading occurs only in yellow Labs (and just to make matters more complicated, fading of the liver/brown pigment in a bb yellow Lab can also occur) . Coat color and pigment is first and foremost determined by alleles at the E Locus. Blacks and chocolates both have the dominant E allele. The receptor of the E locus that produces yellow in the fur of a yellow lab (homozygous e) is a recessive mutant that can only produce red pigment (phaeomelanin, which is diluted to yellow by the alleles of the C locus) in the fur. The same receptor in the skin of that same dog can produce black (phaeomelanin is not produced in skin) but is dependent upon the alleles of the C Locus, which produce tyrosinase, an enzyme needed by the mutant receptor to produce black color. Fading does not occur in black Labs or chocolate (i.e. brown/liver) Labs because the eumelanin (black) pigment produced by the E locus receptor in black or chocolates (encoded by the dominant E allele) is not dependent on tyrosinase encoded by the C locus. Only the pigment in yellows fades because production of tyrosinase is influenced by environmental and some physiological variables. For instance, in cold temperatures tyrosinase is less stable and without tyrosinase, the recessive e receptors stop producing the black pigment. In the case of the Dudley/pink nose referred to in the first question, the c(d) allele does not produce tyrosinase at all, so the mutant receptor encoded by the ee alleles of the yellow dog cannot produce any pigment. *Dudleys or any dilute such as a Silver, Champagne or Charcoal are lacking pigment meaning these dogs have higher risks for cancers, blindness, allergies, skin irritation, hair loss, cataracts etc. *Dilutes- Various expressions of the dilution gene have been noted. Some dogs with dilute color display minimal or no health problems; other dogs experience hair loss and skin problems. Color dilution alopecia (CDA) and black hair follicular dysplasia (BHFD) can accompany coat color dilution. These diseases cause recurrent skin inflammation and drying, bacterial infections of hair follicles and severe hair loss. Minimizing occurrence of these conditions would mean minimization of the dilute mutation.[24] Selection against dilution is important in breeds that display health issues associated with the mutation. It is also important to minimize the dilution mutation in breeds that do not have a standard written to include these colors. The Labrador Retriever is currently one of these breeds. Dilute colored Labrador retrievers are a disqualification according to breed standards. Those dogs carrying the dilute gene should not be registered as purebred Labrador Retrievers. * AKC Standard states a yellow lab shall have black pigmented nose, pads of the paws and around the eyes. A dudley or dilute will not have this. * Equally important to have health testing completed for EIC (Exercise Induced Collapse) which is common in Labradors and can be prevented if the parents are tested and Carriers are not bred. Clear parents will produce clear puppies.. X-rays for hips and elbows to reduce risks of dysplasia. Having eyes checked to prevent Retinal Atrophy.. PRA. .DM. .CNM *Read, read, read and ask questions! Educate yourself as much as possible :) Help future fur babies and families as much as we can and of course most importantly the future of the Labrador Breed *Commonly asked is the difference between English/British labs -referred to as show type and American- referred to as field type .. *English labs typically have a shorter build, blocky head, thick coat, thick otter tail, and commonly more mellow disposition but dont mistake them for not making great retrieves! They still have the love for water, retrieving and are hardy and bred to do so. *American labs typically have an athletic build, longer legs, more lean build, can have a rounded head but most commonly a more narrow face and smoother coat. Are bred to be high driven and often makes them less desired for couch potato life.. Not saying this is correct for all and there are many lines that produce specific traits to change these stereotypes. I of course have owned both types, love combining both American and English together to make the ideal pet, retriever, parter and family member in the home! I also love a full English with the big blocky head and stout figure! ♡ ♡♡
Posted on: Wed, 07 Jan 2015 19:58:32 +0000
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