文脈の流れからとれる意味 - 英語 - 教えて！goo

I once greatly amused by watching his serious gray girl dip her paw very carefully into an empty Ben & Jerry's tub and lick it off, repeatedly. I don't think chocolate is poisonous to cats (as it is to dogs) but to be safe we've stuck with vanilla-based flavors.

この英文の意味は何とか分かるのですが、I don't think chocolate is poisonous to cats (as it is to dogs)の部分で、「猫にとってチョコレートは有害ではないと思う」の後の as it is to dogsは、（犬にとっても有害ではない）それとも（犬にとっては有害だ）なのでしょうか。どちらの意味で解釈すれば正しいのか教えていただけませんか？