My cocker spaniel is suddenly aggressive. Will neutering help him?

This is a very dangerous situation and depending on the trigger for the aggresion neutering may or may not help. I would not recommend this without an individual visit from a certified behaviorist to explore the triggers and patterns of behavior. Please ensure he is not unsupervised, particularly around children until he can be fully assessed

Neutering can help with aggression, so I strongly recommend getting that done for Regan. But he also needs behavioral training as soon as possible. He needs an expert to work with him on his aggressive behaviors to prevent him from hurting another person. I never recommend owners work with aggressive dogs on their own, so speak to his vet about a recommendation to a professional behavioral expert. I would do this today. Best of luck.

There are some breeding lines of red cocker spaniel which do get aggressive when they get older. Their brain seems to grow too big for their head and so they get a head ache and this makes them aggressive. Also other pain/chronic pain can cause aggression in a dog. You really need to male an appointment with a vet for an exam to make sure he does not have a health problem. Once a physical health problem is ruled out, you should consult with a behavioral specialist who will work with you finding the cause of the aggression and how to deal with it and how to reduce the aggression in your dog. Your vet can recommend a veterinary behaviorist or you can find one here: https://avsab.org/resources/speakers-bureau/behavior-consultants-near-you/

Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Certainly male dogs who are not neutered are more prone to fighting and aggression. Neutering him may help but it will not likely solve all the problems. Best of luck.

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. .

Neutering Bruce would be the first step. I would also speak to his vet about getting him into professional behavioral training. I never recommend owners work with aggressive dogs on their own due to safety issues. I would be fearful for you and your children as well, and do not allow him alone with them for now.

You should definitely have him neutered and getting professional help is a great idea. In the meantime, you could start teaching him the "look" command so you can use this command when you want him to focus on you instead of another dog.