please help i have 2 yorkies a male(N) (3.5) and a female (S)(3) and a male pomapoo (N) (1)years old (btw he was introduced in November) . It all started about 2 months ago the female yorkie started viciously attacking the male. Before this they were inseparable (all 3 dogs) they ate played and slept together.The other night she had him by the neck to the point where he almost passed out. I had taken them to a trainer for some help but they were more worried about teaching them how to do tricks versus teaching me/them how to prevent fights and get them back to normal, I also had them checked out at the vet. I have tried a shock collar but nothing, they currently need to be kept in separate rooms at all times, unless both yorkies wear a muzzle. Even with the muzzle on the yorkies they still try and fight, they go after each other making horrible snarls and growls and push each other around. The puppy does not get involved in the fights and is pretty much clueless as to what is going on. Can someone please help me or point me in the right direction so i can fix this problem. I really really really do not want to get rid of any dogs.