THE GOODS : The Puppy Chase : Buying a new pet shouldn’t be done on a lark. Do some planning, ask questions and make sure you’re ready for a long term commitment

People select dogs for all kinds of reasons.

The Jack Russell terrier is currently the canine flavor of the month, due to the charms of Eddie, the Jack Russell starring on TV’s “Frasier.” In other times, “101 Dalmatians” and “Beethoven” upped the popularity--and the prices--of Dalmatians and St. Bernards.

But even though it’s tempting to fall in love with a dog on-screen or even bring home the adorable puppy for Christmas, selecting a companion of years’ duration requires planning and commitment.

“Once a dog comes into my house and pees on my rug, it’s there for life,” says Warren Eckstein, author of “How to Get Your Dog to Do What You Want” (Fawcett, 1994).

If you’ve made the decision to get a dog for someone for Christmas, it’s best to wrap up a leash or biscuit with a note from Santa saying, “Puppy on the way--later.”

A new pet requires a safe, nurturing environment. Glass ornaments and easily toppled trees, poinsettia and mistletoe, turkey bones and chocolate are all puppy hazards. In the middle of the Christmas rush, puppies can’t get the kind of undivided attention they need those first few days away from the litter. Then, “When things get back to normal after the holidays, the last thing people want to do is housebreak the puppy or stop it from chewing up their new Christmas gifts,” Eckstein says.

When the time comes to get your puppy, the advantages of buying a purebred are that you can be quite sure how large it will grow and what it will look like, and you’ll be able to make an educated guess about its adult personality.

“The best source for a puppy is a responsible breeder who is concerned first with health and temperament and second with appearance,” says Wayne Cavanaugh, vice president of communications for the American Kennel Club. It’s important to select a breeder with a good reputation and with whom you feel comfortable.

Ask the breeder if you can speak to former buyers and the veterinarian who cares for the dogs.

Inspect the kennels for cleanliness and check the temperament of the adult dogs. Don’t be put off by a breeder who asks you questions about your qualifications to care for a dog. “The more questions you are asked, the more responsible the breeder probably is,” Cavanaugh says.

For a good indication of how a puppy will look and behave, study the dam and sire. When possible, ask to see the grandparents as well. If either parent growls at you, keep looking. “The mother shouldn’t display shyness or aggression,” Cavanaugh says. “During lactation, it’s common for the mother to lose some of her coat, but she shouldn’t have mange or sores.”

Pedigrees are family trees that indicate how tightly the parents and litter have been bred. In-breeding between fathers and daughters, mothers and sons, and brothers and sisters should be attempted only by breeders with decades of knowledge and experience, Cavanaugh says. The degree to which dogs can be line-bred to other relatives depends on the size of the breed’s gene pool and the breeder’s expertise.

Observe the litter at 7 or 8 weeks--old enough to leave the mother. Avoid the shy puppy in the back of the box as well as the one teething on your hand. Novice dog owners are best off with moderately active pups that greet them and then back off. Watch the pup that interests you for as long as possible to see how it interacts with people and its littermates.

“The puppy should be plump and lively with sparkling eyes and a shiny coat,” Eckstein says. “His breath should be fresh, his gums firm and pink, and his teeth should be white. The rear should be clean, not encrusted with feces, which could indicate diarrhea or some other illness.”

No matter how healthy a pup appears, it should be taken immediately to a veterinarian for an examination. The vet can tell you which defects are typical of specific breeds and check for them. For example, deafness is a problem among Dalmatians. Shar-peis routinely suffer from skin and eye problems, and breeds with dropped ears--such as basset hounds--are susceptible to ear infections and ear mites.

Because hip dysplasia is common in medium-sized and large breeds, make sure the breeder has had the parents--and preferably also the grandparents--certified by the Orthopedic Foundation for Animals.

For any breed, but especially spaniels and collies, experts also recommend that the sire and dam have a recent certification by the Canine Eye Registry Foundation. The certification, in the areas of night blindness and progressive retinal atrophy, is valid for only one year.

Breeders should be able to supply both CERF and OFA numbers for the dam and sire. Do not take the breeder’s word that the parents’ hips and eyes are healthy.

When you buy a purebred puppy, don’t leave the kennel without a blue slip. This is not the dog’s actual registration, but the application to register the animal with the AKC should you wish to. Also, you should have a guarantee that you can take the puppy to a veterinarian and if it is found defective, it will be replaced or your money refunded.

Man’s best friend doesn’t come cheap. The going rate for a “pet-quality” purebred puppy is $300 to $500; show-quality puppies run $400 to $800. Older dogs with ribbons and titles can fetch several thousand dollars.

Following the basic laws of supply and demand, a dog’s popularity, lineage and availability largely dictate its price. Fashion and fad are also key in the pricing equation.

“Unlike cars, there is no sticker price when it comes to puppies,” says Sue Stalioraitis, who manages the classified advertising in Dog World magazine. “AKC papers and price do not denote quality. It’s really buyer beware.”