My work here is done. It’s probably worth mentioning that I’m terrified of dogs!

That explains your irrational attitude towards them then; personally if I spot someone is *really* scared of my dog I call him back and clip him on a short lead; however for some people even the presence of a dog is enough to start of terrified shreaking and running around waving their arms in the air (ie: Japanese tourists, who I have seen run into busy traffic to avoid my dog on a very short lead).
. Personally I don’t see that as my problem, even though it appears some people on here seem to think it is.

If you are scared of them you have every right to be left alone by them; however a dog off the lead isn’t a dog out of control, so you have no right to demand that they be put on a lead/removed just because

Sorry to be a pessimist on this but my view is that once is too many times for this. Not that the dog shoudl be necessarily rehomed or put down but to trust it in a house with a baby, no.

Rather than the water spray ones try the electric shock collars – illegal in Wales but they’d get the message across far more quickly than a spray of water on the nose.

Agree with the first part but vehamnetly disgree with the second. It sounds to me like the dog reacted badly to something it was fearful off, the measures you talk about wouldnt help that.

Marin_Maketh_The_Man – was shaking it from side to side (as gun dogs do when they catch birds / prey etc)

Completely wrong any gun dog that shook a pheasant, partridge etc from side to side would be on its way to dogs home the same day. One of the measures of good gun dog is a “soft” mouth ie he must find the downed bird etc and return it to the handler without damageing it and most of the time the pheseant is still alive and flapping. Note the same does not apply to terriers as no one really cares what state a rat is in.

I think that my parents dog may have mistaken the terrier for a rabbit, and thought it was fair game,

Not a chance the smell is just as important to a dog and it had already been playing with the dog???????

It looks like Mack is going to be given up to a rescue centre,

They need to know about it sight and much more importantly his behavour to other dogs. NOTE some people will have a suitable garden for it to have adequate exrcise.

but as a last resort my parents are meeting an ex-police dog trainer for some advice,

No downside to that but I cannot see what he can say or do about behaviour which appears to be out of character?

The owner was getting rid of Mack, as Macks dad fought with him on several occasions.

Maybe the other way round?

Does anybody else have any experience of anything similar happening, or any sensible advice to offer?

Yes and no I worked in the army as a guard dog handler (the more savage the dog the higher the regard for the dog note Maze prison) and an Arms/explosive search dog handler But at the moment all I can think of is an owner who can keep it away from all other dogs AND children or a one of trip to the vets. A second chance is dodgy unless you are happy with the vets bills and a possible risk to people. Keeping it on a short lead does not sound like something your parents would want??

http://aspcabehavior.org/articles/82/Predatory-Behavior-in-Dogs.aspx

We’ve 2 lurchers + have to be on the ball about this. But as you say, wouldn’t expect it from a gun dog.