Andy needed braces. A crooked tooth was preventing him from closing his mouth properly, so Joseph Medell, like any good parent, took Andy to the dentist.

His choice was Dr. Charles A. Williams, a Northern Virginia veterinarian; Andy is a Scottish terrier.

Medell, who raises, breeds and shows Scottish terriers, spent $500 for Williams to correct his dog's bite with custom-made braces, complete with little rubber bands and detailed cleaning instructions.

"My daughter had braces on when she was young. I love my dog and did not feel funny at all to put braces on him, too," Medell said.

Williams, who specializes in animal dentistry at Blue Cross Animal Hospital, 8429 Lee Hwy., Fairfax, said most pet owners are shocked to learn that their dog or cat might need root canal treatment, bridgework or braces, as people often do.

Williams and his wife, Dr. Suzanne Aller, are part of a small network of veterinarians in the United States who perform dental work on dogs and cats, plus an occasional rabbit or guinea pig.

Williams, 43, said only half a dozen other animal hospitals nationwide specialize in his field. His appointment book includes four-legged patients from up and down the East Coast, as well as the Midwest and Venezuela.

Half the patients that are brought to him for braces are show dogs that accidentally have injured their teeth, said Williams. The other half, he said, are pets with painful, abnormal bites or deformed jaws that make eating difficult.

Williams emphasized that he does not attach braces on show dogs with hereditary teeth or jaw problems, because the rules of competition prohibit such cosmetic changes.

"I won't do it unless the animal is neutered, because then they cannot be eligible for show," he said. "Otherwise, it would be unethical."

One Rockville-based dog breeder called Williams when her prized terrier could not chew properly because his bottom front teeth accidentally had been pulled out of alignment. Williams designed a special set of braces and, three weeks and $300 later, the dog's teeth were straightened.

"He was just so patient when we had to tighten his braces. There was no kicking and no screaming. And when it was over, he would run off and play with the rest of the guys," said the owner. "If you're really into these animals, you'll do everything you can to make them comfortable and have a good life."

With about a dozen $300 to $500 sets of braces a month at -- about one-quarter the price of human orthodontics -- Williams said his business is booming. His busy monthly schedule also includes an average of 25 root canal cases, about 40 gum disease treatments, occasional bridgework and periodic requests for crowns or artificial teeth.

Most artificial teeth patients are police or military guard dogs that break a tooth in the line of duty.

"Sometimes I restore the tooth with a silver metal crown . . . it's very impressive looking," said Williams. He said the stainless steel look is the "Cadillac way to go" for tooth replacements, and costs up to $400.

Williams and Aller, who alternate work weeks so that one of them can care for their 17-month-old son Jacob, keep a cat, two dogs, two goats and five horses, along with chickens, on their three-acre farm in Oakton.

Williams has attached braces and performed root canal treatments on one of his dogs, a 12-year-old Chesapeake Bay retriever named Lucy.

"She sure needed a dentist for a daddy," he said.

Williams, who has been practicing animal dentistry for 11 years and is president-elect of the Veterinary Dental Society, an animal dentistry advisory council, said that he often gets startled looks from pet owners when he launches into his spiel on pet oral hygiene.

"Some people get blown away by it all, but there is still such a great lack of public awareness about home care for pets," he said.

Dr. Colin E. Harvey, professor of surgery at the University of Pennsylvania's School of Veterinary Medicine in Philadelphia, said animal dentistry has taken a back seat in most veterinary schools' curricula because there are so few specialists to teach and publicize it. But, he said, word is spreading and the future looks good .

Aller, who at first was skeptical about the value of applying braces and fake teeth to pets, pointed out that healthy oral hygiene removes the pungent "doggy breath syndrome" in household animals.

"Animal dentistry is aiding in your pet's health," Aller said. "If people went around with decaying teeth, their quality of life would be substandard. Well, the same goes for pets."