My brother found a pile of wood in the backyard and I thought it would be good to give it to my rabbit before giving it to him I looked it up and it said tree wood for them was fine so I let him chew a little but I ended up finding that some tree branches are toxic. My rabbit is 6 months old but if it isn't safe should I be worried about the little piece of wood he bit off? He seems to be doing fine despite chewing it.