Dogs suddenly fighting with each other

Question
Hi there,

I've had 2 dogs for a while now, of nearly the same age. One of them came into the house a year after my first dog and they were getting along fine for over a year.

Now, the "original" dog is attacking the newer one really badly (tearing his fur and wounding him badly).

Now the younger one is scared to even be in the same garden or room.

I walk them both almost every day and they play alot with me, but they can't play together anymore...unless I am there, but even then there is a tension.

What should I do? Many thanks,
Andy

P.S

The older one is 3 and the newer addition to the household is nearly 2 and both adopted from shelters...both healthy according the vet and neither of them are aggressive to people.


I really appreciate any advice you can offer. Many thanks.


Answer
I don't know the breed mix or sex of either of these dogs (although I think they are both the same sex, most likely female), or whether either or both is neutered, therefor I can only give you a guesstimate.  It appears that you may have inadvertently promoted the wrong dog in some way.  Allowing them to interact, even when you are there, without determining the cause of this problem is not a good idea.  You need the intervention of a certified applied animal behaviorist who can evaluate both dogs, interview you in depth, and determine not only cause but possible solution.  You are obviously not in control of either dog and this might be a contributory factor.  since you used the term 'garden' I assume you are in Britain.  Contact the Association of Pet Behavior Counselors, headquartered in London (I think) and get professional help.