Fudo-san (pet shop owner), said that the pet bull would turn out how ever well or unwell the customer treats him. The customer started to neglect the bull's daily care and became obsessed with it's body only, and by doing so, he essentially stopped taking care of himself. The room became a dump filled with food trash and a filthy bed, plus he quit his job. If you look back at the story you will see that during the customers rapid engrossment with the bull's body, the bull was gradually transforming, he started growing horns and became an actual bull that is obsessed with constantly, plowing his owner.
I think the saying "the apple doesn't fall far from the tree", fits pretty well here .
can smbd explains what happened with the cow???? i dont really get it... it seemed like the cow liked it too so why did things turn out that way?