I try to keep a few things in stock at all times; Poly-vi-sol (without Iron), Baby Gas Drops, mineral oil, Neosporin, blue kote, (and now baby aspirin). These things keep for a relatively long time and are for fairly regular use and can be used for multiple kinds of animals (including humans).
PenG is Penicillin G, a penicillin which is injected primarily SubQ(under the skin) with rabbits though it can be injected IM(into the muscle) that use is primarily for cows and horses. This is something I only get in emergencies even though it doesn't expire for years, I usually don't need it for years. They come in various kinds
This kind is the one my tractor supply mostly carries, it uses only one kind of PenG, they also carry a more expensive vial that has 2 kinds of PenG in it (this is the kind I prefer as it covers a wider variety of infection, supposedly) Also ignore the posting at tractor supply; Use .20Ga needles with this stuff instead of .22Ga. This stuff is so thick you would be very lucky to ever push a full dose through the .22Ga. You wind up with a very stressed rabbit trying to be very patient as you apply a ridiculous amount of force to a plunger attached to a needle that is still INSIDE THEM.
Basically with this stuff you do not need to keep it on hand, you just need to know a reliable place where you can get it and the syringes and needles ASAP in an emergency.
Regular use equipment wise I keep just a scale, claw clipper, several droppers and syringes, and an otoscope. I haven't had a need yet for much else.
EDIT- found a picture of the dual PenG that my tractor supply carries which is the kind I use. I use the other kind only when they are sold out of this stuff.
