Like AP said, the point of the piggie "medicine chest" is to be used as first aid until you can get a vet, or rodentologist, involved. They're useful for small things (such as scratches) and to treat an aliment as it begins (for example, if your pig stops eating, you should start hand feeding as soon as you notice).
For my pigs, medically, I have:
- Cotton wool balls (for applying creams and solutions, not really an expense for them because I give them cotton balls from my make-up-removing stash.)
- Nail clippers
- TCP (antiseptic solution, generally it's diluted when being used. I share this with the pigs because, really, you shouldn't double dip or allow cross-contamination of swabs with the solution itself)
- Pro-biotic (I ALWAYS have probiotic; it's useful when the pigs need antibiotics, during force-feeding and if one of them gets an upset stomach)
- Critical Care (I cannot stress how frustrating it is that people don't get this when they get pigs. It's a force-feeding formula packed full of fiber and things pigs need to get better. It's powder form so can be squashed into a syringe too, just add water.)
- Syringes (so, so, so, so many syringes)
- Vitamin C tablets (not first aid, but I sometimes use them in first aid with sick pigs.)
- Metacam (I only have this on hand because I have two pigs who are actively either using it or have permission to be given it as required. Because I have this, I don't have calpol)
- Gripe water (it's inexpensive and I tend to keep it for cases of bloat to help treat it while I wait on a vet opening.)
- Gorgeous Guineas products: Neem oil (sample, used as first-aid, I'm not confident in the product yet to use it as a treatment) bumblefoot ointment (for my elderly pigs who don't move around much to keep the feet in tip top condition) and a melt (for dry skin)
Really, in a first aid box, I'd be delighted if owners just had critical care, syringes, a pain killer and were OK with sharing antiseptic solutions. Everything else is stuff I've collected either for a specific pig or because I've had a problem with a condition in the past and want to be prepared - for a relapse in that pig and secondary in the others - in the future.
I don't keep antibiotics on hand because I'm not 100% sure how to tell the difference between an infection or, for example, a bladder stone, and I prefer to not load my pigs with antibiotics unless they need them. And most other things I get them when I need them.
When making your own, read medical threads and see what people generally recommend most: force feeding (critical care, vitamin c, syrings) if the pig is annorexic, vet if the pig is unwell and the reason can't be pin pointed or antibiotics for an infection (probiotic call) and prepare for that.
Most things, such as critical care, gripe water (for bloat) and probiotics DO have on-hand alternatives in an emergency, though.
