I work for a Canadian EMR company and we deal with a couple of options for medical voice software. I know Dragon naturally speaking has a medical offering that likely would meet any regulatory requirements. There are also some subscription based ones that I don't know if there are US versions of, but If you google the medical options you should be able to find some options.

Thanks Satan

Depending on where you live many municipality's or rescue agencies will spay and neuter strays for free. Maybe worth calling around and finding out if a program like that exists near you.