Hi there jollyjammer, in my own opinion all dogs should be sterilized and spayed unless you are a really professional breeder! Your males are reaching full adolescence whereing the position for pack status is fought and the fighting between them is normal. Some behaviourists would recommend leaving Dad intact, to keep the balance and this is something i think you should discuss with your vet. Do be aware though, that in dogs this age is will take between 6 weeks to 3 months for the test. levels to drop. I would consider getting in a behaviourist in order to help you stop the fighting by way of implementing House rules and show you the appropriate way to treat this type of behaviour. You can find someone via my friendsofthedog site - just look under Our Favourite Links or else by Google. Good luck, Scotty