Good hips are important for a working dog. It allows the dog to move and work pain-free, and have a longer working life - whether that is working livestock, participating in dog sports, or being the companion to an active family.
Around 80% of dogs with clinical hip dysplasia (x-rays show hips that are dysplastic), show few if any outward signs of the disease, at least at younger ages. The only way to know for sure if a dog has hip dysplasia is to have a vet take x-rays of the joints. In the U.S., most hip evaluations are one of two different protocols. Orthopedic Foundation for Animals (OFA) used the hips extended x-ray view, and evaluates whether or not the dog currently has hip dysplasia or not. They give each dog a rating that ranges from Excellent, through Good, to Fair, and Borderline for normal hips, or rates the affected hips as having Mild, Moderate, or Severe Dysplasia.
The University of Pennsylvania developed the Pennsylvania Hip Improvement Program protocol - known as PennHIP. This uses three x-ray views, and measures the laxity of the hips. Results are given as Distraction Indices - DI - that range from 0.0 to 1.0. DIs under .3 indicate tight hips, and a dog that is almost certain to never develop arthritic changes in the hips. DIs over .7 indicate very loose hips, and a dog that is almost certain to develop arthitic changes over time. Between .3 and .7, there is an increasing risk of arthritic changes, and environment plays a large role in whether or not the dog actually does go on to develop issues. Factors that affect the outcome include the dog's weight (less is better - condition scores of 3 or 4), rate of growth of a pup (slower is better), and the type and amount of exercise the dog gets (moderate amounts and good footing are better).
The links below will take you to more detail about each of our dogs that has had hip evaluations. You can look at copies of their x-rays, and read a little bit about what the vet saw in them.