Hi - hoping someone can help.

3 1/2 weeks ago we got a dog from a rescue centre - he is a labrador cross approx 2 years old.

He had a full known history - he was brought in by his previous owners who had had him since he was a puppy because they lived in a flat and worked full time. He was re-homed almost immediately, but the new owners had another dog who he was aggressive towards. They returned him to the rescue centre where he stayed for around a week and a half due to a cut paw before we decided to re-home him.

They told us that he was aggressive towards other dogs and pulled on his lead but that he could be left alone and was good with kids. They didn't know how he was with cats because he had no experience of them.

When we first got him home he seemed like the model dog - never barked (for the first three days we wandered whether he even had a bark), was curious about the cat, but not particularly aggressive, fantastic with my little girl, played ball in the garden without trying to escape etc. During the day he goes to work with my other half in the van and was generally really good. Even the cat was used to him and just ignoring him, with both of them sleeping in the kitchen at night - the only downside was the pulling on the lead which we cured with a halti and a constant impulse to eat the cats food.

After a week and half, he went to the vets to be neutered (two weeks ago Friday). For the week afterwards he was left at home during the day to recover but everything was fine. Then on Monday, he suddenly seemed to undergo a personality change - there is an outdoor dog next door but one who he has suddenly decided to start barking at, at every opportunity, he attacked the cat, completely unprovoked and has started to go mental every time he is let out in the back garden. Over the last two days he has escaped three times, three different ways and even when he is in the house he keeps randomly barking, especially when he hears the other dog.

He's getting plenty of walks and we have contacted a dog trainer who is coming out to do a two hour assessment next week, but I was hoping that some more experienced dog owners may have some advice in the meantime. In particular, I want to try and cure the aggressiveness towards the cat - preferably before the winter - she is 13 and I'd quite like for her to be able to enjoy her old age in some semblance of peace.

I know that it takes time to train a dog, and that his hormones are probably all over the place at the moment, so I suppose I am really looking for some advice to try and mitigate these problems and prevent them settling in. We are really not the sort of people to get a dog from rescue and send him back just because things get a little difficult, but we do have a young child and although he has shown no aggression towards her, the speed of this personality change has scared me a little (we never leave dog and child alone together).

Sorry for the long post - any advice greatfully received.