dog & canine - Horny Dog driving us crazy

Danny,
I agree with you about the comments being off subject, and full of lectures.. I have an 11YO pre need Australian Shepherd, who I wish I had not Neutered . He is the first dog I had ever had that that had been bought from a breeder. I received him as a Christmas present after my Aussie/ border collie mix died the previous month of an angioplastoma. I had always neutered my pets by default, because I believed it was the responsible , healthy thing to do.
Anyway, I neutered my Aussie at around 2 years old because he had become aggressive towards others dogs ,and I had heard from many sources including the vet for whom I worked,that neutering would help ease his aggression. Well, it didn't help a bit! He has been a wonderful companion , but I have never been able to stop this agression. I have had him in training, i have read books, i excercised him more, but nothing has help ed. Furthermore when he was around 8 years old he started getting horny, and this horny-ness has only iincreased with his age. I have asked many vets and they have not been able to figure it out. He is a very healthy dog, but he is about 10 pounds over weight and he has an amazing amount of fatty lumps. I have had thyroid tested many times because i exercise him a lot , mainly frisbee, hiking, or swimming , and i do not over feed him, and i absolutely cannot get him to loose weight. I attribute this extra weight to having him neutured. Neutering a dog is not nevessarily going to stop him from being horny (since testosterone is produced in the brain), or stop agression. My dog has an excellent pedigree,though i never really cared. I just fell in love the minute we met, and is many best buddy.
I would also like to add that I very much do believe that your wife being pregnant could definitely have an affect on your dogs need behavior. Dogs are very sensitive to peoples emotions, and conditions. If a dog can sense the onset iud a seizure, i have no doubt a pregnancy can be noticed. I think most like likely your wife's pheromones are hiw he knows. Regardless,i can see him reacting to them. He will likely be very protective of her and baby as well.