The Merle Genes in Dogs- Stunning Colours, but will too much lead to Birth Defects, skin problems?
Blues, Harlequins, blue eyes the list goes on, but one thing is for certain they tend to be all the craze in the 20th century. The average price for a blue English staffordsire Bull terrier is upwards of $1500, and the average price of your good old brindles and reds is roughly $600. We have observed friends go through nothing but trouble with endless skin problems associated with owning blue staffordshires. We ourselves
owned a blue dobermann some years ago who also suffered with a myriad of skin problems. Being around the show ring for some time we also heard Australian Shepherd breeders saying that you can’t put a merle over a merle (2 recessive gene carriers) as the results can be devastating and can include deafness, small or missing eyes, blindness, dead puppies etc. Is this just a coincidence?
Well, we haven’t experienced first hand any breeding issues with such dogs, but we have had some blue eyed puppies in previous litters, whom we chose not to breed with due to their recessive genes and the possibility of problems further down the line if we met up with another dog also carrying these genes. The genes that are responsible for producing such colours are recessive and therefore for a puppy to inherit the trait that is so we can see it in whatever form blue eyes etc we must have both parents being carriers of the gene (A carrier doesn’t necessarily have to be a blue eyed it just needs to carry the gene).
This article found on wikipedia is interesting and states what we need to be aware of when breeding with these genes.
Merle (In Welsh:Brych) is a colour combination in dogs’ coats. It is a solid base color (usually red/brown or black) with lighter blue/gray or reddish patches, which gives a mottled or uneven speckled effect. Although most breeds that can have merle coats also typically have white markings (such as around the neck, under the belly, and so on), and often tan points (typically between the white and the darker parts of the coat), these are separate colors from the merle; some dogs do appear completely merled with no white or tan markings.
Merle can also alter other colors and patterns besides the usual red or black. These combinations such as Brindle Merle or Liver Merle are not typically accepted in breed standards.
In addition to altering base coat color, merle also modifies eye color and coloring on the nose and paw pads. The merle gene modifies the dark pigment in the eyes, occasionally changing dark eyes to blue, or part of the eye to be colored blue. Since merle causes random modifications, however, both dark-eyed, blue-eyed, and odd-colored eyes. Color on paw pads and nose may be mottled pink and black.
Merle is a distinguishing marking of several breeds, particularly the Australian Shepherd, and appears in others, including the Koolie, German Coolies in Australia, the Shetland Sheepdog, various Collies, the Welsh Corgi (Cardigan), the Pyrenean Shepherd, the Bergamasco Sheepdog, the Catahoula Leopard Dog,and the Old English Sheepdog. In Dachshunds the merle marking is known as “dapple”[1]. Merle is also less commonly found in the Chihuahua, the Pomeranian, the Pit Bull, and the Cocker Spaniel; it is not, however, a recognized color in these breeds. The merle gene also plays a part in producing harlequin Great Danes.
Merle is actually a heterozygote of an incomplete dominance gene. If two such dogs are mated, on the average one quarter of the puppies will be double merles (”double dilute”) and some percentage of these double merle puppies could have eye defects and/or could be deaf. Knowledgeable breeders who want to produce merle puppies mate a merle with a non-merle dog; roughly half the puppies will be merles without the risk of vision or hearing defects.
We are very interested to hear of other peoples experiences with merle coloured genes in dogs, even cats, horses etc whether you have experienced skin problems, deafness, blindness etc or any good results from the cross of 2 recessive genotype+phenotype animals.