A new study found that more than half of people who own dogs expressed some level of canine vaccine hesitancy — i.e. skepticism about vaccinating their pets against rabies and other diseases. An estimated 45 percent of US households own a dog; according to the survey results, nearly 40 percent of dog owners believe that canine vaccines are unsafe, more than 20 percent believe these vaccines are ineffective, and 30 percent consider them to be medically unnecessary.