Veterinarian Brendan McKiernan of Wheat Ridge, Colo., a board-certified internist, disagrees.
"They don't dissolve in the stomach," he says. "When we take them out, they're not digested. And they are causing both esophageal and intestinal problems in dogs to an extent that is concerning."
But McKiernan believes incidents are underreported. Earlier this year, at a meeting of the American College of Veterinary Internal Medicine, a group of gastroenterologists discussed obstructions caused by "compressed vegetable chew treats" such as Greenies. By an informal show of hands, he says, "a significant number said, 'Hey, we have problems.'"
Be very careful about what you feed your dogs, and make sure that they are supervised.