[big black dogs]

Looks like some sort of contact dermatitis. It could be he was laying on something that irritating it? Or it could be from a bug or fly bite? It's best if you don't allow him to lick and bother the area. Let us know what the vet says.

 

[big black dogs]

The problem with putting ointment on his testicles is that he will try to lick it off and irritate it even worse. I would see if you can give it a bit of a scrub with some anti-bacterial soap, dry the area...and put on some shorts or underpants on him so he cannot lick the area. A cone of shame would work...but it often gets the dogs upset to wear. I always keep some Vetericyn on hand for scrapes, bites and irritations. You spray it on. Order it on Amazon.

 

[big black dogs]

That's a real shame!! He should not be in agony from a razor burn. They do have to shave before doing surgery. Did you get any pain meds to give after his neuter surgery?? I would again put something on him so he cannot start licking. The more he licks the more slowly it will heal and be done with. Call the vet and ask what to do.