Researchers have recently shown that antioxidants can significantly mitigate the effects of aging on the brains of dogs.

"Oxidative damage is the key feature in the aged brains of animals and people," Dr. Carl W. Cotman, a neurochemist employed by the University of California Institute for Brain Aging and Dementia, told a New York Times reporter.

Studies funded by Hill's Pet Nutrition, the National Institute on Aging and the United States Army showed that older dogs receiving a food fortified with antioxidant-rich fruits and vegetables performed significantly better on cognitive tests than elderly dogs fed a brand of dog food commonly found in supermarkets.

Researchers working at the United States Department of Agriculture's Human Nutrition Research Center on Aging (HNRCA) managed to delay and even reverse the effects of aging on rats? brains during a similar study by providing a diet rich in blueberry, strawberry and spinach extracts.

"It's very plausible that antioxidant-rich diets would also help older dogs," said one of the HNRCA researchers.

"Dogs are typically more than 11 years old when owners first detect clinical signs of cognitive dysfunction syndrome," said Gary Landsberg, DVM, a veterinary behaviorist who practices in Thornhill, Ontario. "However, in the laboratory, we can often see subtle changes in cognitive function at 8, 9 or 10."

The signs of cognitive dysfunction in dogs due to aging include disorientation and changes in behavior.