This is one of the links that I found, but I don't know if it was written by a vet. Still looking for more. http://www.avianweb.com/medicationsexotics.html
I read that, too, but I also read something that was published by a vet that said penicillin w/procaine should be avoided due to procaine toxicity. Penicillin, by itself would be fine, but I don't think the injectable comes without procaine. I will try to find the source and post it.