Zane Grey 
Wildfire 

The red stallion did not appear to be hurt. The twitching of his muscles must have been caused by the cactus spikes embedded in him. There were drops of blood all over one side. Lucy thought she dared to try to pull these thorns out. She had never in her life been afraid of any horse. Farlane, Holley, all the riders, and her father, too, had tried to make her realize the danger in a horse, sooner or later…