If there's no great heat or bounding pulse, I wonder why you were thinking abscess? Without more info I'd guess 6 months of 'rest' may be the more likely culprit. Obviously sometimes it's unfortunately necessary to do that, but keeping horses cooped up is not good for them in a range of ways, including causing soundness issues. The rest could have also been the reason for an abscess too.
so, is it possible to get an abcess with no puncture wound, or cracks or anything?
Absolutely. Puncture wounds cause abscesses(or worse) but they're not common. Cracks & otherwise 'open doors' to infection can sometimes result in an abscess, particularly if there are also mechanical problems IME. But abscesses commonly come about due to hoof bruising, contraction or otherwise 'assaulted' hooves, where the tissue is damaged or dies and the abscess/inflammation is the body's way of pushing the necrotic stuff out & healing the injury. So...
does a hoof abcess need antibiotics? I have smz pills I can start her on.
I disagree generally with antibiotics or bute(anti-inflams) for abscesses - don't suppress it, let it 'rip'. But you can help it come to a head & relieve your horse's discomfort with soaking & more exercise the better - tho don't force her either. At any rate, you don't even know if it is an abscess & I wouldn't be giving anti-b's to a horse without very good reason & vet's advice. If for what ever reason the vet does advise, I'd be feeding a probiotic after the anti.
She has about 1 Inch of really nice growth coming in. The clubbed foot does seem to have some chipping at the bottom and 1 crack (superficial sand crack) on the outer wall.
Not sure what you mean by the first sentence but sounds like the other inches aren't nice growth?? Perhaps she had terrible feet & your management has allowed for a start on nice ones? If so, abscesses wouldn't surprise me, as they're a common thing that goes with compromised hooves. Chipping just likely means she's due for a trim & while I'd take notice, I wouldn't stress about it.
Superficial cracks just in the outer wall are IMO generally diet/nutrition &/or the horse has been living in a damp/wet environ too long. Either way, healthy diet & well balanced nutrition will make them less susceptible to this, so it's great that you've started her on a good supp - & will hopefully soon notice these cracks growing out & getting less
. Especially if the horse isn't in a dry, clean environment, I would however be concerned with seedy infection getting in & worsening the cracks, so I'd get the farrier to deal with them assertively if he feels the need & advise you on appropriate follow up treatment.