Canine Hip Dysplasia (CHD) is a polygenic, inherited disease. "Polygenic" simply means more than one gene is involved in the disease. Hip dysplasia means "badly formed hip" and refers to a malformed hip socket. Diagnosis is usually made by x-ray.Depending on the severity of the malformation, outward signs may be absent or the dog may be in severe pain. Mild cases may be treated using anti-imflammatories, while the most severe may require surgery.

The OFA has provided the following recommended breeding guidelines:

Breed normal to normal.
Breed normals with normal ancestry.
Breed normals from litters with low incidence of CHD.
Select a sire that produces a low incidence of CHD.

Having mostly hip-cleared relatives on both sides of the pedigree is thought to increase the chances of breeding clear hips.

From 1974 to December 1999, 378 Toller hip x-rays were submitted to OFA, with  7.7% of those submitted proving dysplastic.

More information on CHD can be found at the following links:

Orthapedic Foundation for Animals (OFA)
http://www.offa.org

PennHIP (University of Pennsylvania Hip Improvement Program)
http://www.vet.upenn.edu/pennhip/

Australian Hip Rating System
http://www.acay.com.au/~dissi/sbc/hipdys.htm

PennHip vs. OFA
http://www.workingdogs.com/ofa_penn.htm

Canine Hip Dysplasia page features radiographs of surgical treatments for CHD
http://www.k9web.com/dog-faqs/medical/medical-info.02.html#HD

A collection of links to Hip Dysplasia sites
http://www.workingdogs.com/doc0090.htm