What is the main problem in Old Yeller?

The main problem in Old Yeller is how Travis Coates, who is 14, will be able to take care of his mother and younger brother, Little Arliss, while his father is away on a long cattle drive. Part of Travis's dilemma is how he will handle Old Yeller, the name he gives the mangy dog who shows up at the family's house and consumes all their meat.
At first, Travis struggles to deal with the tasks of being head of the house, and he also struggles to control Old Yeller. The dog cavorts in the family's drinking water with five-year-old Arliss and fails to go after two bulls who are fighting. However, Old Yeller then saves Arliss from a bear, and the dog becomes invaluable to Travis in catching the heifer, Spot, who has run away. Old Yeller also saves Mama and Lisbeth, a neighbor, from a rabid wolf, but, as the dog has contracted rabies, Travis must shoot Old Yeller. In the end, Travis, though sick at heart after killing the dog, has proved that he can serve ably as the head of his household.