Health experts have long agreed that petting a dog or cat can lower blood pressure. But now, scientists in South Africa say that the family pet can also serve as a form of Prozac, increasing the release of endorphins and other hormones tied to pleasure.

Those findings inspired researchers at the University of Missouri to launch a similar study. Their goal? To come up with cold, hard data about the health benefits of pets.

One project involving cancer patients and dogs is already under way. It examines the effects of dogs on cancer patients in radiation therapy, said veterinarian Dr. Richard Meadows, a lead researcher and acting director of the Center for the Study of Animal Wellness at the university. "We expect to find that the dogs are a source of comfort and relaxation, and exert a calming effect on the people. There are connections between mental attitude and the immune system, and we want to look at that."

A second study will mirror the research done by South African Dr. J.S.J. Odendaal, and measure levels of five chemicals in the brain that are connected to feelings of warmth and security, stress reduction and social bonding. Odendaal found all five hormones peaked in both the humans and the dogs when they interacted.

The American team wants to replicate and expand on those results - and eventually perform the same tests with cats and other pets. If this study yields similar findings, it could have significant impact on how doctors treat emotional problems such as depression and anxiety, and even certain physical illnesses.

When salmon runs on the Yukon River in Alaska collapsed earlier this year, few realized the impact it might have on Alaskan sled dogs, which are critical to life in many Alaskan villages. Villagers use sled dogs to check trap lines, haul water and firewood, and travel between villages.

The state's governor Tony Knowles declared a disaster in the area. There were so few fish that even subsistence fishing for food had to be halted. Then reports surfaced that some dog mushers were having to kill dogs rather than watch them starve.

Since then, tons of dog food and fish have been donated for distribution to dog owners. Ralston Purina Co. in October donated 22.5 tons of dog food. Twenty-thousand pounds of sockeye salmon went to the dogs after King Triton Fisheries went bankrupt. And most recently, Pets.com, the online retailer that shut down early last month, donated more than 21 tons of dog food.

Several Fairbanks-based air carriers stepped in to help get the dog food and fish to the villages. The U.S. Postal Service agreed to ship donations of more than 200,000 pounds as bypass mail, cheaper than regular mail. And the Humane Society of the United States has volunteered to coordinate donations and delivery of not only food but high-calorie supplements, such as lard or oil, to get the dogs through the harsh Alaska winter.

Donations may be sent to Alaskan Dog Relief Project, HSUS Northern Rockies Regional Office, 490 North 31st St., 215, Billings MT 59106.