Diseases Associated with the Australian Shepherd Breed
The Australian Shepherd, like all breeds of animal, has known
defects. You should purchase ANY breed of dogs being aware that there is
no one perfect breed and research the lines from which you do decide to
purchase. There are many diseases (as in people) that 'just' materialize
without being present in their sire and dam. Read these articles and make
informed decisions about your purchases.
General information on Diseases associated with the
Australian Shepherd can be found at this website
http://www.ashgi.org/articles/gen_info.htm
The Dirty Dozen Plus a Few: Frequency of Hereditary Diseases in Australian Shepherds
Originally published in the 2000 Australian Shepherd Annual
http://www.ashgi.org/articles/health_surveys_dirty_doz.htm
Aussie Genetics Fact Sheet: Australian Shepherd Genetic Disease Prevalence
http://www.ashgi.org/articles/fact_prevalance.htm
Aussie Genetics Fact Sheet: Epilepsy
http://www.ashgi.org/articles/epilepsy_canine_epilepsy.htm
This is a direct quote from the article listed above and the
entire article and more can be read at the above links:
"Inherited epilepsy, also called "primary" or "idiopathic" epilepsy, has long been recognized as a canine disease. It is seen in both purebred and mix-breed dogs, but some breeds, like the Aussie, have a much higher incidence than that seen in dogs as a whole. This is the result of the inbreeding inherent in the development and maintenance of any purebred population. The founders of any given breed will have only a subset of the genes—good and bad—present in the canine species. Selection over generations for desired traits will limit that gene pool further and not all the genes retained will be for desirable traits. If, at some point in a breed's history a particular sire or line of dogs becomes predominant, inherited problems may start to arise seemingly out of nowhere. Attempts to concentrate the desirable genes of the select individuals, can inadvertently bring together whatever undesirable genes are present.
Inherited epilepsy is often called "idiopathic," which means of unknown cause. The terminology is no longer accurate but was developed at a time when no one realized that genes could cause the disease. Primary epilepsy is perhaps a better term because it indicated that the epilepsy is not caused by some other factor.
Epilepsy presents one set of problems to a dog owner and another to a breeder. It is a terrible disease and not something any breeder wants to produce, but avoiding it can be difficult. We don't know exactly how it is passed from one generation to the next. Dogs may not develop the disease until they are old enough that they may already have offspring. Failure by some to disclose information can make it impossible for others with related dogs to take effective steps to limit risk of producing epileptic dogs.
While primary epilepsy is now recognized as inherited, the mode of inheritance is not yet known. It is possible that there are several genetically distinct types of epilepsy, though any one breed will likely have only a single type. In Australian Shepherds, it is clearly not dominant or one would see it following clear lines from parent to offspring generation after generation. A sex-linked condition would result in many more affected males than females, which is not the case. This leaves either recessive or polygenic modes of inheritance. In either case, a healthy parent can produce affected offspring and both parents must be carriers.
For Australian Shepherds, the mode of inheritance remains a mystery. There are currently two research projects that are looking at the disease in the breed. One is conducted by VetGen, LLP, a commercial laboratory working in association with the University of Michigan. The other is at the University of Missouri. Both need DNA samples from family groups including both affected and non-affected individuals. A "family" includes at a minimum affected dog(s), plus parents and siblings."
