My dog LOVEs oranges, I asked the vet about it and he said it was ok in small quantities. He actually whines when I peel an orange untill he gets some. He loves all fruit actually, no grapes though.
Hm. I think oranges are one fruit all of my dogs would turn away. And I have some piggies! Grapes and raisins are a no-no. Careful of fruit with pits too.