[note: edited for content: Saturday evening]
 
 
Have you heard of the crop support? It's kind of like a bra for crops, and some people swear by them.
 
 
A woman in Vermont {where I live} was going to have to ethically euthanize her beloved chicken due to a crop issue—ongoing; had tried everything her vet or others could think of, devastated; tried the support, and immediately saw results.
 
 
Happy chicken, today.    
 
 
 
She {the seller/maker} can do custom sizes, too; each item is made to order.
 
 
It might offer additional wound protection while healing, too.
 
I've not used or seen one, in person.
 
VERY reasonably priced; less than twenty bucks.
 
I do NOT work for or with her; I am not trying to sell or hawk anything; I simply hoped it might help.
 
 
Good luck; sending good thoughts your way.
 
 
Please do post a status update, if you get the chance...
 
 
Heal well: both of you. 
 
 
[Link: 
http://crazykfarm.mybigcommerce.com/birdy-bra-crop-supporter-chest-protector/]
 
 
...
 
 
Regarding antibiotic? With surgery? I'd suggest systemic: i.e. internal, rather than putting ANYTHING directly on or near wound, until it heals significantly.
 
 
Caveat:I am not a vet or medical practitioner.
 
My ex husband is a surgeon: human species: Homo sapiens: we do tend to pick a few things up when exposed intensively, and curious; please understand that I am not claiming any healthcare background.
 
 
Fishmox? I had a TERRIBLE experience with; another animal; I've tried it only once, in a bind: I do NOT trust their quality control AT ALL.
 
I'm sure another, savvier chix person might recommend a reliable brand.
 
Honestly? I'd go for people antibiotics, type/dosage/treatment protocol recommended by vet, but I understand that this is often not culturally appropriate with chickens.
 
In my limited experience, the emergency vet will answer these Qs over the phone for free, particularly if you have established a rapport and/or approach gently and cautiously and assure them that you are not litigious. I often use words like, "Hypothetically" in conversations.  I've NEVER had them not respond to my queries with genuine concern and advice, no charge, over the phone.
 
 
 
...
 
By the by?
 
I am about to try administering aspirin to a cockerel; do you have any experience in guestimating weight? Could he be only 12-16 oz at age 13-15 weeks? That's what I'm guessing. Less than a pound.
 
I believe a bantam something-frizzle-barred rock mix... I CANNOT do huge amount of water... the recipes I'm finding online call for solutions/dilutions.
 
I'd like to try a portion of a baby aspirin; do  not, obviously, want to hurt him.
 
I bought the baby aspirin today; about to try a splint, too, want to give aspirin first.
 
 
I had never even met a live chicken until a few weeks ago. Argghh... Nervous as all livin' get up.  
 
 
I gave him yoghurt and sweet potato {cooked} prophylactically about an hour ago to help sooth any GI issues; if aspirin causes upset.
 
Risk/benefit?
 
He's in pain.
 
 
Sorry, thought you might know.
 
A rescue/{at least until he heals: indoor pet, effectively}/first chicken ever; me: newbie.
 
 
Thank you...