Old Yeller was a classic movie from 1957. Old Yeller was a loyal dog. He protected his family from a bear, wild hogs, an angry cow, and then finally from a wolf.
Sadly, Old Yeller caught a disease of the brain that turned him from a protector into a deadly menace to the family. His teeth dripped with infected saliva as he snarled at the family that used to love him.
The family had the sad duty to put him down.
The end.
I remember the movie well. Had Fess Parker in it.
Old Yeller had rabies.