I'm no vet, but it didn't look tremendously bad to me. And I've
seen alot of incisions in my time with cats getting fixed!!
If you are way concerned - you may put some Bactrin or Neosporin on the skin to help.
The antibiotics they use for flesh wounds/infections is usually
Clavamox which is amoxicillin with clavumox (sp!!) added.
roughly 62 mg for the cat is the dosage for Clavamox.
You can find / use the FISH antibiotics no prescription required, sold at Petsmart for fish. (Little known but true, fish use antibiotics just like we do...
only for fish they don't require a prescription...)
Fishmox is the name -- fish amoxicillin. You have to cut and adjust
the dosage however, as the fish pill/capsule contains way more than the prescribed dosage for cats.
However, you probably will NOT need to go there. Seems that it might be healing on its own nicely...