A first-of-its kind study indicates that dogs, like humans, may inherit an Alzheimer's-like disease, according to UC Davis researchers. The findings also show that dogs may provide an animal model to help study Alzheimer's, which affects some 4 million Americans over the age of 65. "This is the first time the familial link has been demonstrated in dogs with Alzheimer's-like disease, and it is the first time researchers have looked at dogs with Alzheimer's-like disease that have been raised in controlled conditions," says Michael J. Russell, an assistant professor of anesthesiology at the UC Davis School of Medicine. The researchers, who recently published their work in the neuroscience journal NeuroReport, examined archived brain tissue of 29 beagles from the National Radiobiology Archives. The beagles were involved in a now-disbanded UC Davis research project on low-level radiation. Most of the dogs in Russell's study received no treatment; they were members of a control group. Brain tissues were sampled from dogs in 13 litters. "We not only found that aged dogs develop plaques that are strikingly similar to those found in the brains of Alzheimer's disease patients," Russell says, "but that the occurrence of plaques is highly correlated among litter mates."