My brother's dog, Theo, is a farm dog who could roam to our neighbor's ground and potentially father an unwanted litter of puppies. Spaying and neutering are the best way to reduce the 4 to 6 million unwanted pets euthanized each year. Even though males can't get pregnant, they can sire multiple litters. I thought you said neutering would not change my dog's behavior. Neutering can decrease roaming behavior, marking behavior, and some forms of aggression, but genetics and training are more important contributors to your pet's behavior.
People think neutered dogs are more sleepy and less playful than usual after castration.
In fact, those behavioral changes are typical of puberty, the stage of life when most neutering occurs. The changes merely reflect your pet growing up. But don't blame obesity on being neutered. Any dog can become obese. Obesity should be controlled through proper diet and exercise.