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When breeding Aussies, one of the first things to consider is color because the breed's beautiful merle colors have a lethal side. The homozygous merle puppy produced from a merle to merle mating may be deaf and/or have eye problems ranging from slight to complete blindness. If your bitch is solid black or red, you probably will want to breed her to a merle male simply to get a variety of merle and solid color puppies. If you breed her to a solid, all of your puppies will be solid colored. With a solid colored parent, you will not have any problems with the defective merling gene.
However, if your bitch is merle, you must make one decision. Are you prepared to cull the defective white puppies? If not, breed her to a solid dog. If you decide to breed merle to merle, there are a few basic things to know:
The defective puppy is not caused by one defective gene. It is the unfortunate side of our merle genes which produces the beautiful merle patterns. The defective puppy is the pure merle puppy, which averages one out of four in a merle to merle mating. Something we do not completely understand about the merling gene is how the gene breaks down the coloring in an otherwise solid dog, and also affects eye and ear development in the fetus. When the solid gene is present with the merling gene, the results are a sound merle dog. When the merle gene is joined with another merle gene (homozygous merle), a defective puppy is the result.
In litters from merle to merle matings, they will statistically average one defective, homozygous merle puppy out of four. This will vary from one to many defective puppies in a given litter. If you realize these puppies are going to be deaf or have eye defects, it is not too difficult to cull them at birth. This should be done as soon as possible after whelping since there is no reason to stress the bitch with nursing extra pups. If you cull all puppies with white off the blaze, collar, socks, white chest and belly patterns, there are no borderline pups. Defective, homozygous merle puppies are often primarily white with just patches of color, and nearly always have a lot of white on the head. Puppies with each eye surrounded with color, color over the ears, and no white on the body behind the shoulder should be sound. The patterns seem to be the key. Sometimes a puppy without very much white, but with mismarkings on the body, such as a stripe running up from the underside, will be defective.
There are many breeders who said they would keep excessive white puppies long enough to see if they are sound. They then are faced with the sad task of having a cute, fuzzy puppy destroyed because it is deaf, blind or both. Some people have given these pups away, or even sold them. If you really care about the Australian Shepherd, don't do it! That white Aussie is advertising the Australian Shepherd Breed everywhere it goes, as well as your breeding program. So many times the end of the story is the heartbreak of the child you gave that cute white puppy to crying because the dog never knew the family car was coming- he never saw or heard it start.
The best way is for you, the breeder, to cull those white-factored puppies at birth, and then to forget them and enjoy your healthy, sound litter. Another option is to simply do a solid to merle breeding, and eliminate the possibility of the homozygous merle.
Individuals do exist in the breed with excessive white markings, but which are sound dogs. They are carrying the genetic makeup like a pinto or piebald horse, which simply causes white body spots. Also, puppies may be from a bloodline with a lot of white markings, and a puppy is born where the white simply went to far. Breeding these dogs should be discouraged for an obvious reason: if the breed carried genetic possibility for sound puppies to be marked like defective puppies, there would be no way to make a determination at birth. No one wants to make a decision to cull five or six week old puppies. To keep these defective puppies easily identifiable, the excessive white individual must be kept out of the breed's gene pool.
As a breeder, please educate your puppy buyers regarding merle to merle matings. BE A RESPONSIBLE BREEDER!!!
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