Why id my 10 month old dog is becoming aggressive?

I have a ten month old springer spaniel and is very much my dog. he sits on my knee and follows me everywhere and has never been aggressive with me. my brother has come back from uni and my dog is beginning to stare at him and into space and growl and back and bare his teeth. ive tried calming him and he has bit me twice now which hed never do. I grabbed him by his scruff after pinning him down for him to stop and put him in his cage and he had tears down his little face as if he felt bad for hurting his 'mum'.Is this cause he needs neutured? Or is he ill? He has never been an aggressive dog this is so unlike him. help!

He might be stressed for some reason..i'd nueter him anyways because it always lessens the dogs chances of getting cancer!

It sounds like he is at the age that we would call puberty. It could be due to an increase in testosterone levels (neuturing him would resolve this and I completely encourage it!).Make sure you don't threaten him as that will not help anything. Pinning a dog down should never be done as this takes away their sense of wellbeing. By all means, punish them accordingly when they do things but don't take it one step too far. You want him to know that you're in charge, not that you own him in a slave-like way.Sorry if it's not very informative!

Woah, woah, woah. What do you mean you grabbed your dog by the scruff and pinned him down? That is NOT the way to handle this situation. You're teaching your dog to fear not only your brother, but you as well. Your dog doesn't need to be bullied into submission; that is no way to train a dog.He does need to be neutered, as 90% of all dogs do, and this will help with the aggression. However, my long-term suggestion would be to devote time and energy into getting him well-socialized. Find a local dog park and take him there at least 3x per week. This will allow him to get socialized with other people and dogs, which should help with the aggression at home.As for your brother, when he is home, encourage him to feed the dog, take the dog on walks, and play with him. Cut yourself out of the picture as much as possible and allow him to take over. This will help your dog acknowledge and respect your brother as a pack member, not an intruder.

This dog should have been neutered four months ago, so it needs to be done NOW. You also need to contact a professional trainer and work with them to correct this issue. Aggression is not something that should be handled at home by someone who isn't experienced with what they're doing. You can make a bad situation much, much worse. Dogs don't comprehend time the same way people do and they don't associate punishment with their actions unless it happens IMMEDIATELY after the behavior. Even thirty seconds is enough time for them to be confused about what you're angry about.You should also never put a dog in a crate as a punishment. This will only make the behavior worse. Their crate should be a "safe zone" for them to go to and decompress. Using it as a punishment will just make him insecure and an insecure dog with aggression issues is dangerous.This dog needs to be neutered and needs professional training. Aggression will only get worse until it's addressed by a professional.

It is quite possible that neutering him will cause him to be less aggressive. It is also possible that it is something that must be trained put of him. What was your dog's life like before you adopted him? Is it possible that he was abused or neglected by a man. Hearing that he reacts to your brother negatively leads me to believe he has a problem with men. But that should change as he spends more time with men that are good to him and he realizes he is not in danger. It is something you should address with your vet.

Springers do get rage syndrome (Springer Rage Syndrome). I hope that's not the case with your's, but it could be. Google it.

Ever time he bites u slap him on the bottom little hard and tell him no growls or bare at bur brother slap him on his bottom