What decision does mama make about the dog and why old yeller?

Mama ultimately decides to put down Old Yeller because he is bitten by a rabid animal, which poses a serious threat to the family’s safety. Despite the deep bond they share with Old Yeller, she understands the necessity of protecting her family from the disease that rabies can bring. This decision reflects the harsh realities of their frontier life, where difficult choices often have to be made for the greater good.