Is my 5-year-old dog too old to neuter? Will it help his behavior?

Now is the best time to neuter them both. Neutered males are more docile and make better pets. When they reach sexual maturity at around 6 months and their hormones go into full swing so to speak, they may act aggressive toward other males and want to become dominant in the household. If you wait too long, neutering will not help. I suggest neutering all dog sin the house as soon as possible, then the hormones will die down in a few weeks. At this time, implement a training program with a trainer or by doing some research. The behavior will most likely get better, but that is not definite. Neutering with combined training is your best plan to change his behavior. .

Withering of male dogs is advised between 4 and 6 months of age. Here is wonderful resource to explain the many benefits; https://www.petcoach.co/article/5-great-reasons-to-spay-or-neuter-your-pet/ The only behaviors that will be affected by castration are those that are under the influence of male hormones. So for example, a dog’s temperament, training, and personality, are related to genetics and upbringing, not hormones. Neutering does not “calm” an excitable dog, and unless a castrated male dog is overfed or underexercised, there is no reason for it gain weight or become inactive. The undesired traits which are related to male hormones such as sexual behaviours, aggression, and urine marking will change over the course of a few days to a few months. I hope that is helpful information!

Neutering will keep him from roaming as much although if he continues to go outside he may still fight with other cats. The urine marking in the house may stop but there is no guarantee as he is already older. If they are neutered young (like less than 6 months of age) then that behaviour is virtually non-existent. So, to answer your question......maybe some of the bad behaviours will stop but there is no guarantee. Regardless, it is better to have him neutered and I highly recommend it.

Castration will have the following benefits: No more icky discharge from the penis or prepuce, no incentive to roam and look for females, if the dog shows some aggression, castration will usually lessen aggressive behavior. A lot of entire males are constantly upset and excited if they smell females in heat ( and the smell can travel for a mile and more), No chance of making babies. Here is more info by the ASPCA: http://www.aspca.org/pet-care/general-pet-care/spayneuter-your-pet

It sounds like Kiba is entering the stage where is hormones are telling him to get all the lady dogs pregnant, and to keep away other male dogs. I would recommend neutering Kiba to keep him out of trouble. Fights with other male (and even female) dogs can turn ugly very quick. Neutering at this early age should prevent long-term aggression, but it can take 6-8 weeks for the hormones to completely leave his system. Unless you are planning to breed Kiba, there is no medical benefit to leaving his testicles in a this point. His chill personality should be locked in, and testosterone is no longer needed as he should be done growing at this point.

Neutering will decrease testosterone levels which can in turn decrease chances of aggression, so any dog that is intact and is having aggression issues, neutering is recommended. That being said, sometimes the behavior becomes more of a habit and because of this, neutering isn't a 100% guarantee to fix the issue, but it is at least the first step.

The only behaviors that will be affected by castration are those that are under the influence of male hormones. So for example, a dog’s temperament, training, and personality, are related to genetics and upbringing, not hormones. Neutering does not “calm” an excitable dog, and unless a castrated male dog is overfed or underexercised, there is no reason for it gain weight or become inactive. The undesired traits which are related to male hormones such as sexual behaviours, aggression, and urine marking will change over the course of a few days to a few months. I hope that is helpful information and I wish you the best of luck with Nipper's surgery.