This is a personal decision that you should make in consultation with your veterinarian. Neutering a male Doberman can help prevent testicular cancer and reduce the risk of prostate problems. It can also help reduce aggression and roaming behavior. However, neutering can also have some negative effects, such as increased risk of obesity, and it may not be appropriate for every dog. Your vet can help you weigh the pros and cons and make the best decision for your dog.