The "greening" of American backyards -- as more people turn to composting food scraps -- is turning some dogs a bilious shade of green. Certain microorganisms and the toxins they produce can sicken or even kill dogs that get into the wrong compost pile, a Cornell University veterinary toxicologist is warning.

"We're seeing more and more cases of 'compost poisoning,' where the fermentation of meat, dairy products and other food in compost piles produces clostridial toxins that can be very nasty to a dog," said Larry J. Thompson, D.V.M., Ph.D., a toxicologist in the Cornell University College of Veterinary Medicine's Diagnostic Laboratory.

Samples sent to the Cornell Diagnostic Laboratory from throughout New York state and the Northeast give veterinarians an early warning about disease and toxicological trends in the animal population, and they now have a renewed concern about "garbage gut."

"Particularly in warm weather, when animals ingest garbage with clostridial toxins, we see severe vomiting, severe diarrhea, dehydration and sometimes death if garbage gut is not treated," Thompson said. "As more people utilize compost for degrading biological materials -- if they're not judicious about what they put in their compost and how they protect their compost pile -- dogs and other animal can smell the meat and gain access to the compost."

Composts can be a microcosm of potentially harmful bacteria to meat-foraging pets, according to Patrick McDonough, Ph.D., a microbiologist at the Cornell Veterinary Diagnostic Laboratory. He pointed to Clostridium perfringens, Campylobacter jejuni, Yersinia enterocolitica, Staphylococcus aureus and some of the Salmonellae and Bacillus species as prime suspects.

In any case, meat scraps have no business being in backyard composts, said Dan Cogan, a compost technology expert at the Cornell Waste Management Institute.

"It's true that meat can be composted in some of the high-tech, in-vessel systems that are now in commercial use," Cogan said. "But please don't try this at home -- for a number of reasons, including the 'attractive -nuisance' problem with dogs and other animals. Also, if you simply make sure your pile is enclosed on all sides, dogs won't be able to gain access."

Most of the compost garbage-gut cases recorded at the Cornell Veterinary Diagnostic Laboratory involve dogs, Thompson said, hoping to alert pet owners to hazards in their own backyards and to encourage owners to monitor the health of dogs that roam the neighborhood. "Dogs are not put off by smells that offend us humans," he said, "and dogs -- more so than cats -- will eat garbage without hesitation. It takes all kinds of organisms to make a compost work, but a dog isn't one of them."