It's hard to say how many people buy pets online. Web sites offering puppies advertised as AKC certified, home-raised and healthy go against recommendations by the experts.

One of the first things to look at instead of the cute puppy photos on the site is the warrantee. One breeder in Tennessee specifies that the warrantee she offers for her puppies does not include undescended testicles or loose patellas.

Luxating (or loose) patellas are kneecaps that pop out of alignment because of a malformation of the joint. The American College of Veterinary Surgeons describes patellar luxation as the most common congenital anomaly in dogs, diagnosed in 7 percent of puppies.

Studies have found a predisposition for the anomaly in 32 breeds. In 82 percent of the cases, dogs with patellar luxation are born with it. Most must be surgically repaired.

Dogs with undescended testicles are called Cryptorchid. The American Veterinary Medical Association states it is unethical for a veterinarian to surgically correct this condition without also neutering the animal to prevent treated cryptorchid dogs from being deceptively presented as reproductively normal. Because of the potential for an increased incidence of torsion or cancer within the retained testicle, it is strongly recommended that all of these individuals be neutered.

Another breeder's warrantee states: "There are certain disorders that may be caused by environmental factors for example: allergies, thyroid dysfunction, demodectic mange, and other autoimmune disorders that are not covered by this guarantee."

According to the AVMA, demodectic mange may signal an underlying medical condition. There is strong evidence that a predilection for juvenile demodectic mange is inherited. Demodectic mange is caused by a mite in a dog's hair follicles. While it generally never causes a problem, in dogs with impaired immune systems, intense stress or malnutrition, the mites can reproduce rapidly, and lead to widespread inflammation, and infection.

Another online breeder states, "Although we do everything we can to ensure the health of our puppies, our health guarantee does not apply to kennel cough, coccidia, diarrhea, collapsed trachea, giardia, open fontanel or parasites."

According to Dr. Randi Olson of Vale Park Animal Hospital in Valparaiso, these issues should not be excluded. Roundworms and hookworms can be passed from the mother, who should be free from them before being bred.

Coccidia is easily prevented by keeping the dogs' environment clean.

"If they're doing a good job they shouldn't have kennel cough and they definitely shouldn't have parasites," she said. "Healthy puppies that are well taken care of don't normally develop kennel cough. If I see a puppy that comes in with ear mites, or intestinal parasites or fleas, it says it's not a very good kennel."