He has alexithimya, that's why he's not right in the head. He actually doesn't think that fckng a dog is normal, in the novel he tells Josh that this was all a lie he created because Chase wouldn't get rid of their pheromones so he tried to say something absurd to make him accept the fact that he need to release pheromones. Josh also punches Grayson after their dialogue, idk why they changed it in the novel. This conversation is in Stewart's clinic too.

Actually wtf is wrong with the brother? This is obviously not normal, how does he attain this level of insanity? He’s normalizing beastiality and basically abusing his brother…