As your dog reaches old age, you might expect to contend with veterinary complaints like hip dysplasia or even cancer. But here's one you aren't as likely to expect: Alzheimer's disease. According to veterinarian Lee Harris, the condition is surprisingly common. At his veterinary practice in Southern California, he's seen an increase in chronic conditions such as obesity, arthritis and dementia. "Really, our brains are not that different from dogs’," Harris wrote in The Washington Post.