Dr. Stephen Stang, Purcellville, Va. About 1 1/4 hours outside of D.C., but, well worth it. I wouldn't go to anyone else. And, they do clinics at his practice.
Same with me. I got the results I wanted with half the price tag. ASK your vet if they do them often, find out if other breeders use them. My vet is not popular with the lab crowd but the rhodesian folks use her. I got good/normal under a tough OFA panel.