Is Breeding a Chocolate Labrador to another Chocolate Labrador Bad?
Are Chocolates "weaker" than the other colours?
Not Necessarily
As far as my research has taken me, I cannot find that breeding Choc to Choc is in itself bad.Read the note from Pam Davol (below) when I asked her advice. Pam has a human medical background (B.S., M.Ed. is a research scientist in the field of biochemical oncology (cancer) and experimental pharmacology) and is a longtime breeder of Labradors. Her web site is Wing and Wave.
The Problem
The reason that there seems to be more problems with Chocolate labradors in any particular geographic area is probably due to line breeding and in breeding within the area. More advice and definitions from from Pam Davol is detailled below.
The more ancestors that the dogs have in common, the higher the chance that "bad" recessive traits will be expressed. Nothing to do with the colour of the coat, this would be true of all colours of lab and indeed all breeds of mammals (including humans!)
"Style" and Breed Standard
Breeding Chocolate to Chocolate where one both parents have a recessive gene for yellow, will produce lighter eyes in the Chocolates, variation in the coat colour, and yellow dogs with "pigmentation faults", yellow coat colour but "chocolate or liver colored eye rim, lower lip, and nose pigment". Pam's words on this issue, see below.
But if you want a family pet and are not going for the show ring, these "faults" are in the eye of the beholder.
Strength of Type in the Blacks
A general belief is that the Black dogs have a better record for "Conformity" - adhering to the "Breed Standard". The closer to the standard a dog is, the better it will be built to be a working Labrador - minimising the chances of the underlying bone structure of the dog causing hip, shoulder or elbow problems.
So, further to this belief, is that if the Chocolates are bred to a well conforming Black, the resulting Chocolates will be of higher quality.
The Black coat and eye traits passed on will also ensure that the Chocolates will have darker coats and dark eye colour - a preference for the show ring.
Look at Chocolate Labradors bred to the standard, type 1, and bred for other reasons, type 2. To my eye, the main difference is the head shape, with the conforming Labs having the "broad skull" you would expect to see. The "type 2" dogs seem to have a narrower skull and lose the typical labrador look - people often mistake them for German Shorthaired Pointers. They would still be lovely dogs, bred for their temperament only, not for their looks.
More informaion on
GENETIC DEFECTS AND BREEDING PRACTICES IN THE LABRADOR RETRIEVER Jack Vanderwyk, January 2004
Astrochoc's Recent Experience
Knowing about the recessive yellow issue and my female carried a yellow (bbEe), I looked for a stud dog who was dominant on the expression gene (bbEE). I found a quality stud with this genotype (ie he had never produced yellow pups when mated to a yellow female), and checked his pedigree chart for ancestors in common with my female. Look at Sires pedigree, and Dam's pedigree.The stud dog was also chosen because he was not a tall dog, because my female tended to be a bit leggy - ie she is about as tall as a female Lab can be within the standard. Also he had a lovely friendly happy temperament.
I don't have enough information to judge why 2 of 6 of the pups of this mating have come out with OCD in their elbow. Perhaps it is just random genetics and very bad luck for us all.
So this result is a warning to breeders and buyers to lessen the odds by finding out hip and elbow scores and PRA outcomes for as many dogs as they can in any given pedigree before breeding or buying decisions are made.
As stated before, nothing can absolutely guarantee that any given litter or your pup will have no problems. We are at the mercy of the randomness of genetics.
If ALL breeders took the actions of minimising the risk of passing on the bad traits, then the chances of getting a bad outcome will lessen over time. So carefully choose a breeder who is taking all the steps they can.
Advice from Pam Davol
Breeding Chocolate to Chocolate
I have been getting many inquiries on this particular topic. Apparently, someone on one of the forums has indicated that breeding chocolate to chocolate increases risks for skeletal disorders, etc. because the gene responsible for chocolate is a recessive.Although there are disorders linked to some coat color genes, these genes are typically only those that occur in absence of color (such as albinism) or in the case of the dominant Merle allele (produces the patches of blue and yellow observed in some breeds) which when inherited from both parents may be either lethal to the offspring or produce eye and hearing disorders (the dominant form of this gene is not present in the Lab). The recessive genes for chocolate and yellow in the Lab have not been associated with any physical abnormality or disorder, nor has any genetic defect been documented in the medical literature as having a relationship to carrying the recessive alleles that encode these colors (either alone or in combination). As to OCD: OCD affects black Labs as well as chocolates and yellows, the latter of which both carry recessive genes for coat color. Certain litters are predisposed to developing OCD but documented factors that influence expression of OCD in a particular dog do not include coat color.
Some genes, like those for some forms of cataracts and one form of retinal dysplasia, do occur as incomplete dominants, however, not all incomplete dominant genes have deleterious side effects (similarly, not all recessive genes are bad). Sometimes, coat color genes will behave as incomplete dominants (this is particularly true of the agouti--A locus-- genes for coat color), however, these genes do not result in any deleterious side effects. This is true of many incomplete dominant genes, even in humans. To put it in context: Blaming every coat color incomplete dominant gene or recessive gene for physical defects in dogs would be the same as saying that every person out there with green eyes (due to incomplete dominant) or blue eyes (due to recessive) is at higher risk for genetic defects!
