Doggie coats and booties are more than fashion accessories and a couple of extra pounds of fat is healthy when it comes to "winterizing" dogs for outdoor activities, according to trainers of some canine athletes that make human Olympians look like couch potatoes -- the sled dog racing team at Cornell University's College of Veterinary Medicine.

With a little preparation, almost any healthy dog can accompany humans on winter running, fitness walking or cross-country skiing expeditions, said Arleigh Reynolds, D.V.M., Ph.D., assistant professor of clinical nutrition. The Alaskan huskies that are involved in Reynolds' nutrition studies at Cornell and trained by students to run in sled races are well suited for winter life, he notes. But even the racing huskies need extra care in extreme conditions -- a lesson that can be applied to family pets.

"Keep in mind what your dog is built for," Reynolds advised. "Not all dogs can handle cold weather. Some of the small, short-coated dogs like Chihuahuas are never going to be comfortable in a cold environment. And other breeds, such as Norwegian elkhounds, Samoyeds, Huskies and Malamutes, actually are more comfortable in the cold than in a warm environment. Most family pets fall between those extremes, so your average Labrador retriever, for example, has a coat that keeps it fairly comfortable in cold weather."

The professor/musher offers these tips to successfully share winter activities with dogs:

• If weather conditions allow humans to be comfortable, running with normal sweat pants and breathing without a face mask, dogs such as retrievers will do fine. But if it's so cold that humans need a face mask, then dogs are at risk of frost bite. Especially vulnerable are females that recently have had puppies or males with little hair on their underbellies. Specially designed dog coats can protect the abdomens of dogs that are out in cold weather.
• Even champions in Alaska's Iditarod race wear dog booties, so suburban pooches shouldn't feel bad when they're led to the pet-supply store for a fitting. The uninsulated booties are not for warmth, the Cornell expert noted, but for two kinds of protection: For preventative health care if the dog may run through changing conditions -- from water to snow that forms balls in the hair of the feet or from powder snow to granular snow or ice with sharp edges -- the booties prevent injuries. In deep-snow conditions, where dogs' feet spread out and snow acts like tiny knives to produce cuts between the webs of their feet, Rover will be grateful for the fashionable attire. And if the dog already has a cut pad or other minor foot injury, booties help the injury heal faster.

Taking the dog in for a fitting is a good idea, Reynolds said, because a boot that is too large won't give proper traction on slippery surfaces. Openings at the top allow snow to enter the boot, also causing injuries. And a too-small boot can cut off circulation to the dog's feet. Check the condition of the booties from time to time to ensure that the dog hasn't worn holes in the bottom and that the boots aren't too tight.

• Adjust feeding as winter approaches to add a pound or two of insulating weight to active, outdoor dogs. That much weight will not make normal dogs obese, and they can shed the extra pounds when the weather warms in the spring.

Don't forget water for working dogs in the winter, even if they are eating snow, Reynolds said. An active dog can't get enough water from snow, and it uses extra energy to melt the snow. However, the electrolytes in sports drinks are not needed, the veterinary nutritionist said, because dogs don't sweat the way humans do.

• Equipped with their naturally thick coat and adapted to the cold, many dogs can thrive outdoors if their yard includes a shelter from precipitation and wind. The doghouse should be appropriately sized -- just large enough to allow maneuvering while retaining the animal's body heat -- and outfitted with dry bedding.

All dogs reach their cold-tolerance limit at some temperature, the Cornell husky-trainer said. "If it's so cold that you can't go out without extreme cold-weather gear, your dog shouldn't be outside at that temperature either.

"Bring the dogs inside then," he advised. "That's the true meaning of a 'three-dog night.' They'll be happy to keep you warm, too."

Those amazing canine athletes, the Alaskan huskies of sled-dog racing.

Cool facts from the College of Veterinary Medicine at Cornell University:

• Although almost any "Northern" breed of dog may run in the Iditarod, the most successful mushers field teams of Alaskan huskies. The Alaskan husky is not recognized by the American Kennel Club (AKC), as are such breeds as the Siberian husky and Malamute. It is a mix of those breeds, with superior speed and endurance.
• The average Alaskan husky running in the Iditarod burns about 11,000 calories a day. To put that in perspective, compare a 44-pound dog with a 175- to 180-pound human in an endurance event like the (Tour de France) bicycle race. On a body-weight basis, an Iditarod racer eats and burns about eight times as much as a Tour de France cyclist.
• In another physiological parameter, the maximal oxygen uptake, or VO2 max, the huskies also are champs. The human who won the 1996 Olympic marathon in Atlanta had VO2 max of about 75 mils of oxygen per kilogram of body weight. Dogs running in the Cornell sled dog team have VO2 maxes as high as 240 -- three times as high as the very best human athletes in the world.
• The average human recreational runner in an endurance event such as a marathon usually clocks 9-minute miles. Alaskan huskies in the 1,000-mile Iditarod, running in a variety of harrowing conditions that would turn a human marathoner blue, average 9 or 10 mph -- the equivalent of a 6-minute mile. And the dog teams are pulling sleds that weigh, at the beginning of the race, between 300 and 400 pounds.
• Besides endurance, Alaskan huskies are prized for their super-insulating coats of inner and outer fur. A musher considering buying a new husky sometimes borrows the dog for the night and lets it sleep on the snow. If snow beneath the dog has thawed overnight, the dog is a "melter" with insufficient insulation and probably isn't worth buying.