Season 3, Episode 23 - "Mixed Blessing"
Back in St. Olaf, Gretchen Vigbotter had a thing for Buddy, but Mr. Vigbotter didn't approve and tried to keep them apart. One day, he caught them in a "most indelicate situation" in the front yard. He yelled at them to stop before he turned the hose on them. What was unique about Gretchen and Buddy?
They were dogs.
Dorothy: Wait a minute. Wait a minute, Rose. Buddy and Gretchen weren't people, were they?
Rose: Of course not, they were dogs! Gretchen was a Dalmatian, and Buddy was a Schnauzer. And Mr. Vigbotter wasn't too happy when he ended up with a litter of Schnalmatians.