red, sore testicles

Question
I have a 2 year old male newfoundland.  I have taken him to our vet several times concerning sores that he gets on his testicles.  They get very red and raw.  Our vet has treated him with antibiotics and antifungal spray in the past.  The sores never seem to go away completly--and at times they are very painful.  Do you have any ideas?

Answer
It could be a lick granuloma if the dog licks at his testicles.
Otherwise it is most likely caused by rubbing, either from the legs rubbing against the testicles or the testicles resting/rubbing against pavement, concrete etc.
I highly recommend castration and feel this would most likely solve the problem