No and never heard of it. I just searched it and the only Vet school in CA at UC Davis says it has regular volunteers. Dogs must be 55lbs and over, on flea and hearworm meds.
I would volunteer Molly if there was no expense to us. I have donated blood myself. Most people think blood is needed for terrible accidents, but a lot of it goes to cancer patients who's blood count gets low from chemo and people who become anemic after a scheduled surgery.