Over 15,000 years ago, early humans domesticated wolves and created a friendship that has stood the test of time. Since then dogs have proven to be loyal, friendly, and hardworking to boot. And none are more beloved than the film star Lassie.

While this collie was first played by a pedigree female, she refused to swim in the river and was replaced by a male dog named Pal. Since then, all nine Lassies have been male, and all of them descendants of Pal. It turns out that male collies don’t lose their coats as often as females and are therefore more suited to their movie closeups.

On National Dog Day, celebrate your own furry friends who are awfully glad that you are in their pack.

Today we also celebrate: National Cherry Popsicle Day, National Got Checked Day, National Webmistress Day, and National Women’s Equality Day.