What is the name of Rainie's dog that Old Dan gets in a fight with in Where the Red Fern Grows?

The Pritchards' dog's name is Old Blue. 

The blue tick hound is, like his owners, "mean and ugly...a big dog, tall and heavy...his chest...thick and solid".  Rainie Pritchard had bet Billy that Billy's two dogs could not catch the notorious "ghost coon", and just at the point where Old Dan and Little Ann tree the elusive raccoon, Old Blue comes upon the scene, having chewed through the rope with which Rubin and Rainie had tied him.  Old Blue is itching for a fight, growling and walking "stiff-legged around Old Dan, showing his teeth". 

Rubin and Rainie are roughing up Billy when Old Dan finally responds to the challenge from the blue tick hound.  The two dogs tear and slash at each other, and the weight of the bigger Pritchard dog pushes Old Dan over.  Seeing her companion getting the worst of the battle, Little Ann goes to his assistance, even though it is highly unusual for a female dog to fight.  She locks her jaws around Old Blue's throat, and Old Dan slashes at the aggressor's soft belly.  Rainie yells that Billy's dog is killing Old Blue, and Rubin takes Billy's axe to save the hound.  Before he can get to the dogs, however, Rubin trips and falls, impaling himself with the axe.

Billy manages to get his dogs off Old Blue, saving his life, but Rubin, with the axe embedded in his stomach, is mortally wounded.  He dies before help can arrive (Chapter 13).