The impact of anti-vaccine activists is spreading beyond humans. A recent study found many dog owners are skeptical of vaccinating their pets — even though that leaves animals and humans at risk.

The study, led by a researcher from Boston University's School of Public Health and published in the journal Vaccine, found a sizable minority of dog owners have some hesitancy toward canine vaccines. Over one-third (37%) said they believed the shots were unsafe; 22% thought they were ineffective; and 30% thought they were unnecessary. Overall, 53% of dog owners endorsed at least one of these three misconceptions.

Motta says an unvaccinated pet is a danger not just to other animals but also to the humans around them.

While almost all states require rabies vaccinations, there are several other shots that veterinarians recommend for dogs.

According to the American Pet Product Association, about 65 million households in the U.S. have at least one dog.

For California resident Sinjin Chun, vaccines keep him confident that his dog Koby will stay safe while playing with other pets at the beach.

The study also found that some common vaccine misinformation has been projected onto pets.

This is no evidence vaccines cause autism in humans or animals.