Determination
Nearly every action by Billy and his dogs is an exercise in determination. To start with, Billy demonstrates great determination in simply getting his dogs - he works odd jobs for two years to save up enough money to buy the hounds, then walks through the night to pick up his hounds. The dogs return the favor. Little Ann does not deviate from the trail of a coon, whereas Old Dan never gives up the chase - Billy has to force him away. If Billy ever falters in his will power - as when he has to chop down the big sycamore for the dogs' first coon - his love for his hounds restores his determination. Many characters comment on the persistence of the dogs, notably during the championship hunt in the blizzard. Old Dan is determined until the very end - Billy must pry away his jaws from the mountain lion. Only after Old Dan dies does Little Ann show a loss of will power, but this is because she and Old Dan - and Billy - were a team who fed off the others' strong determination.
God and spirituality
Billy prays to God throughout the novel in difficult times, and his prayers are usually answered. He often discusses prayer with his parents, and feels God is somehow on his and his dogs' side. However, his faith is shaken when his dogs die, as he cannot understand why they were taken from him. The killing of the mountain lion, known as the "devil cat," seems tinged with religious themes and provides some kind of answer; the dogs have rid the environment of evil and made it a safe place. They are rewarded with the sacred red fern, which restores Billy's faith. He believes they had a mystical purpose on earth, and he can better understand their deaths.
Sacrifice
We see many instances of selfless sacrifice in the novel, and often one sacrifice leads to another. Whenever Grandpa gives Billy candy, for instance, Billy gives it to his sisters. Charity is also crucial to the novel, as characters constantly help each other. Hunters buy Billy's wares when he is saving up money for the hounds, Billy's family often helps him, and during the championship hunt all the men help Billy out in the blizzard. But the deepest sacrifice is that of Old Dan and Little Ann for Billy. Old Dan sacrifices his life (as does Little Ann, by extension) for Billy in the fight against the mountain lion. The sacrifice turns out to be not just for Billy, but for all the animals in the woods terrorized by the mountain lion and for the Colman family - thanks to Old Dan and Little Ann, they now have enough money to move to town.
Love beyond loyalty
A character notes that Billy's hounds seem to have more than just loyalty for their owner; they love him deeply. This love is affirmed throughout the novel and contributes to the sad ending. Throughout their adventures, we see how love, and not mere loyalty, enables the team to survive and succeed. It is almost as if Billy, Old Dan, and Little Ann are one being. Rawls uses the color red throughout Where the Red Fern Grows. Red is the color of blood, as well, and through this association it symbolizes the dogs' deep love, their strong will power, and their sacrificial intimacy with each other and Billy - not to mention the mystical qualities of the red fern.
Family
Billy is very close to his family. They support him whenever he needs it, and the unspoken message is that the family bonds together at all costs during the economic hardship of the Great Depression in the 1930s. Billy is perhaps closest to his Grandpa, who teaches him all he knows about coon hunting and is his greatest hunting supporter. At one point, Billy notes that no one can know a boy like his grandfather, and their relationship is possibly the most humorous, and meaningful, one in the novel.
