Veterinary drugs

I need some direction please! I have a character who has access to all types of vet drugs-in particular equine or large animal-

My character has a lot of people to kill- but needs to do it quietly- Right now I have him using large amounts of ketamine- but I am looking for something that induces unconsciousness quickly and then eliminates the respiratory drive- or a good paralytic would help as well- anyone have any ideas?

thanks so much!

Thanks backslash! that helps- Now I just need to come up with a believable scenario to work it in- my husband is an anesthetist, but I need to know if a vet would have Sux on hand in a mobile unit. I have horses and I know our vet comes with a SUV that servs as a mobile pharmacy and trauma unit in one- every thing they need they have in there- but I'm wondering if they would carry a paralytic/depolarizing agent like Sux with them- thats why I chose ketamine- I know they carry that-but ketamine takes a long time to work- particularly if its given IM- so it would work- but I wanted something faster acting- i am tempted to call my vet and ask- but they are so busy I hate to bother them-
My husband of course is just rolling his eyes at me and shaking his head- pffhhht!

My husband does agree that sux is fast and effective- so I think I might go with it- but it will be administered IM, which will take a few minutes for it to take effect- and the vic will have that time to stirke back at my bad guy- gotta work that out a bit- but I think I can make it work! Thanks!

I was thinking of using a dart gun Jim, and yeah I know, however my killer doesn't really care if they catch him- at long as he finishes what he sets out to do- after that- he could care less if he lives or dies- but he is determined to kill those he blames for the death of his wife first- wife was a vet and has all the drugs he needs in her clinic on wheels-