sexual behavior on castrated males

Question
Helo... I adopted my six-year-old dog from the city pound when I was living in LA. He was 3 months old and was castrated. I returned to my homeland in Brazil when he was about 3 years old. I had never seen him develop any sexual behavior prior to that. He had been a very shy dog up to that moment. When I say he had been shy I mean it took me 2 years to be able to taking him out for a walk around the block - he would simply freeze whenever I took him out.
Fortunately, I was able to make him enjoy going out for a walk a year before I left the US but prior to that, he had never been in touch with females.
Turns out my mother has 3 bitches and I spent a year at her home when I first got back. Enzo - my dog - started to show sexual behavior with the non-castrated female at first. Last weekend, he showed the same behavior with a male dog and with my nephew's leg. I asked his vet if that was normal and he was puzzled due to the fact that Enzo was castrated at such a young age.
Is there anything I can do about it? Is it all right that Enzo tries to copulate with other dogs even though he's castrated??
thank you!

Answer
Thais -

Sexual behavior is dogs is often due to dominance issues - especially when a male dog is concerned.  Perhaps your dog is trying to take a dominant stance with the male dogs in the neighborhood.  He may actually have a behavioral issue rather then sexual issues.  

Your dog may still be attracted to intact female dogs - even though he cannot mate with her. It is not uncommon for a male dog to be attracted to a female dog even though he has been neutered - the attraction can still be there even after the testicles are gone.  Even so, he man also be asserting his dominance with the females, too.  If your dog was very shy in LA, perhaps he feels the need to assert himself in a different environment.  His shyness may manifest in a dominant role in order to compensate for being so timid.  

Try to socialize your dog by exposing him to dogs at the dog park and other public places.  If that does not work, consult a trainer  or have a behavior consult with  a veterinarian that specializes in training.

Best Regards,

Charlotte Sherrell, DVM