Is rhubarb poisonous? Not certain it the best thing for dogs to be chewing at...Jack just been munching on milk thistles( cultivated for tortoise)
but, rhubarb leaf?

Rhubarb leaves are certainly toxic for humans, but I've seen sheep eat them without apparent harm, so I've no idea how a dog would react. Best err on the side of caution and prevent it.

Thanks for that, I wasn't certain but had some vague memory of it not being good. He has relinquished it, a little reluctant, I think its a playful half hour. I shall  be watching for any more attempts at it though.
Karen