The urge to reproduce and pass on their genes to the next generation is intense in unneutered dogs. Both bitches and dogs will be strongly motivated to get to each other at the appropriate time. When sexually mature, an unneutered dog will tend to wander, if he gets the chance, in search of potential mates, risking getting involved in traffic accidents or being picked up as a stray by a dog warden.
An unneutered bitch will come into season twice a year, and must then be kept under tight control to avoid unwanted pregnancies, since she will always be on the lookout during these times to get out and mate.
If they can’t get out, unneutered dogs will often go off their food, soil in the house, be extremely restless and whine in frustration.
There are significant medical benefits to be gained from neutering your dog. Neutering prevents the following medical conditions:Testicular cancer- Neutering removes the testes and eliminates the risk of your dog developing testicular cancer, a common and life-threatening cancer in older male dogs.Prostate problems – Without neutering, your dog’s prostate will gradually enlarge as he gets older. This can become uncomfortable for him and even make urination difficult. If the prostate becomes infected, it’s difficult to treat without neutering. While neutering doesn’t completely guard against prostate cancer, it does prevent enlargement and possible infection of the prostate.- source