All responsible
breeders of the Australian Shepherds, will do the basic
testing to ensure they are producing genetically sound puppies.
And although doing the tests, only mating to those tested and are
known to be genetically sound does not mean that genetic issues will
not arise. Breeding clear stock is never a sure shot.
Recessive genes can and do rear it's ugly head from generation past,
sometimes as from very far back in a pedigree. But it is every
responsible breeder's responsibility to test and research before
breeding to up the odds of producing a genetically sound healthy
puppy.
The most
basic of testing will include, OFA or Penn Hip ratings for Hip
Dysplasia and Elbow Dysplasia, CERF for eye clearances. With
Patellar Luxation being very important with in the Miniatures's that can be
from breeding for smaller size in a breeding program to quickly.
And a huge and growing concern is Epilepsy which I have added as
it's own chapter.

http://www.ashgi.org/articles/gen_info.htm
Recommended sites
for more information:
http://www.offa.org/
http://www.pennhip.org/
http://www.workingdogs.com/doc0090.htm
http://www.vmdb.org/clinic.html
http://www.ashgi.org/index.htm
http://www.westernhillsaussies.com/genetics.html
http://www.mascaonline.org/Health.htm
http://members.aol.com/miniaussie/Frames7.htm