Here are some links to see what Medical DNA tests are available for your breed(s) currently.  Doing the DNA medical tests will help with future breedings to screen for certain known genes that are linked to specific traits such as PRA, CEA, CK, TNS, MDR, etc. and to help those looking for a puppy to know that their puppy comes from lines that have been tested and either shown clear or that are carriers.

At this site you can see a list of different tests and the labs doing the testing
http://www.offa.org/dnatest.html

These are the links for the USA companies and the tests for certan breeds they can currently do - your breed's parent organization is the one to encourage and promote these tests so if you do not see your breed listed you may want to contact your breed's parent club and inquire about getting things started.
** http://www.optigen.com/opt9_test.html  (seems to offer the most tests at one location)
    http://www.vetgen.com/index.html
    http://www.offa.org/dnatesting/
    http://www.vdl.umn.edu/vdl/ourservices/canineneuromuscular/home.html
    http://www.vetdnacenter.com/index.html

This is the USA company that can do the testing for MDR-1 test (Canine Multiple Drug Sensitivity test)
    http://www.vetmed.wsu.edu/depts-VCPL/test.aspx

This is the link for the Canadian company (Toronto, Ontario) and the tests they can currently do.
    http://www.healthgene.com/canine/breeds.asp
    http://www.healthgene.com/canine/C142.asp

This is just one of the links for the UK
     http://www.aht.org.uk/genetics_tests.html