Happy National Service Dog Month!

This month we celebrate the pooches who live to serve. Here are five things you may not know about these service stars.

Around 20,000 dogs work as assistance animals in the United States, according to the American Humane Society—more if you add therapy and emotional support dogs. The first guide dog school opened in 1916 to train canines to care for World War I veterans.

Cori, the Swim Instructor

This Labrador–golden retriever mix helps teach kids with disabilities how to swim. They’re cute, but don’t ask

them to shake. These dogs are workers, not pets. You can tell many service dogs by their vest, but there is no requirement to wear identifying garb. Retrievers are a popular service animal because they love to fetch.

Knoxville, the Veteran’s Assistance Dog

The 4-year-old Labrador and golden retriever mix responds to more than 40 commands from his owner, who lost his legs in Afghanistan.

Visit Parade.com/knox for more of Stefan LeRoy’s story.