I have 2 adult Mastiffs. They are brothers and started to have terrible fights. I am thinking of putting one to sleep. Can you offer any advice?

First off, I love your site, but need more help in Dog to Dog Aggression...

CASE HISTORY: We own 2 male Fila Brasilieros Mastiffs...They are brothers, same parents, different litters, separated by 6 months ....Older dog is now 3 years old, Young dog now 2 1/2 years old..Both sit, stay, down and are crated ....Until 3 weeks ago they got along fine, with an occasional spat over a toy or bone....not serious.

Problem: Younger dog is now attacking the older dog, without warnings (growling or posturing)...and draws blood ...Younger dog does NOT attack, Husband, Wife or 8yr old son. We have had to separate them or attacks would be everyday and every opportunity. The dogs are now being let out of their crates separately. Older dog conducts himself in his normal manner while out with the family. The younger dog seems on edge, not his usual affectionate self while out with us. He seems to be focused on the older dog in the back of the house in his crate. This started 3 weeks or so ago, gradually increasing in intensity.

Older dog does nothing perceptible to our eyes to warrant/encourage the attacks, once it starts the older dog does not immediately retaliate, older dogs barely fights back and always seems as though he had no idea the attack was coming....like he is being blind sided.

We are at a crossroads and hope to gain some advice/insight. The younger dog is a good dog, the behavior issue is only about his aggression, which is a major issue when he weighs 175 pounds.

We feel it might be a power play by the young dog to change his position in the pack. They are an extremely pack orientated breed.

QUESTION: will neutering STOP this? Will the lack of testosterone take his emphasis off of breeding rights, dominance in the pack and his overall attitude? We love this dog and do not want to have to destroy him, but he is not to be trifled with and we do not want it getting worse.

We are weighing all the options, we have always owned dogs and never had one like this. If we can find enough evidence that neutering will help we will have him done, but if it is only a long shot we do not feel it is right to put the dog through surgery if it is not necessary.

We are prepared to put him down, though it is our last option.

Any insight or thought you may have would be appreciated, thank you in advance for your time.

Thanks,
Cindy (wife and owner of the younger dog)