Those things work really well on cattle still on the hoof. I've been known to use some cattle fly spray on my pants legs occasionally but, it's not recommended.
I couldn't get syringes for allergy shots several times (war on drugs issue) so, I seriously considered going to my large animal vet but, I hated large bore needles! I have used them for various projects in engineering school during college though.
However, a meat injector option for a holiday roast or ham never crossed my mind. Hmm ... those would surely beat the @#$% ones I find locally in the grocery stores.