Hi all I have a 9mnth old westie that has turned very very viscious within the last 2 days or so. He has bitten my disabled mothers feet and drawn blood and has done the same to my fathers hand. He has never shown this much aggresion before now jsut the odd snap at fingers when hes tired; but this seems to be for no reason. Im going to get him a muzzle i think today cos I fear he may go for someone in the street and then that will almost certainly spell the end for him. what can I do would getting him the snip help to calm him down at all or is there a class that can teach him out of this behaviour. your help is urgently needed in the matter i dont know what to do for the best.

I would have him to the vet, to make sure there isnt a health issue first, to explain his sudden change in behaviour. 
Sometimes if a dog is ill, or in pain, they will snap and bite.

HTH

Firstly, the class won't teach him - it is intended to teach you.  You mention that he has never shown this much aggression before  just the odd snap of fingers!   I would suggest that you join a reputable class where you will be shown the correct way forward.  Castration isn't the answer. 

> Im going to get him a muzzle i think today cos I fear he may go for someone in the street and then that will almost certainly spell the end for him.

Talking about "the end" of a puppy is so sad.  I do fear that you have just reached the "kevin" age and don't know how to deal with it.  He's only a baby, and this is not a normally vicious breed.  Perhaps your lack of training means that he has got away with more than he should - but you can turn that around by finding a decent reward based training class, who will give you loads of knowledge to help you with your boy.

However, your first port of call should be the vet - and not to arrange castration!  Just get your lad checked over to rule out any medical problems.  Although it just sounds like he's realised that he's male, and is challenging.

He has never shown this much aggresion before now jsut the odd snap at fingers when hes tired;

This type of behaviour really should have been extinquished a long time ago, when a dog is allowed to get away with snapping and growling at owners as suggested, when they reach the adolescent stage it is going to go one degree further as it is the most disobediant stage. Terriers on a whole are more vocal and growly at getting their opinions across but unless you are being unreasonable i.e moving and fussing a dog whilst sleeping etc a dog should do as it is told and like a child should not answer back by growl or snap and certainly not by bite.

From puppyhood the dog should have been put in time outs when disobediant or challanging, your back should have been turned and the dog ignored, this gets the message across that the behaviour is unacceptable. How are you reacting when the dog bites? The one thing you must not do, if you are - is become angry or challanging yourself it teaches a dog nothing, a stern No! With good strong eye contact and a time out will teach him much more, so I would suggest you start that immediately.

You need to begin praise and reward training, asking him to do things for you with a reward (treat, fussing over) he will soon realise the different reactions he gets from you, good and obediant gets reward, biting, growling, not obeying commands he gets segregated for a few minutes and ignored.

Above all else get your eye contact with him sorted, one look from you should make him stop, your in charge here not him, he can not rule the roost, give him an inch and he will run with it. So firstly try to take control back, you can turn this around, secondly if you find there is no improvement bring in a behaviourist it's easier to teach you how to train him in person rather than on an internet as obviously we can't see how things are being done and the body language you are both giving off.

Don't be unreasonable with him and lord over him, just remind him who is the boss when he oversteps the mark.

Does he have plenty of toys he can play with and does he get played with with them? Does he get any training :)

Under what circumstances exactly has he bitten the feet and hand? was he underneath something or out in the open?

Some classes may be good but many will suggest wrong techniques unfortunately.
I'd suggest looking at these:

http://www.apdt.co.uk/local_dog_trainers.asp

http://www.apbc.org.uk/regions.php

whatever you do, don't just get someone from the local paper as they may not be very knowledgeable, as anyone can set up as a trainer or behaviourist.

Good luck :)

I agree with all the above posts.
What did you do when he used to snap at people? if you just shouted at him and then carried on he will of learn that this isokfor him to do.
I would say a calm but firm NO and then remove him from the room for time out.. When is calm again bring him back into the room and ask that ever one gives no eye contact and ignores him, when he setttles down then call him to you make him sit and then give him a reward or fuss for being calm. Give him attention on your terms not his to reinstate who is boss.
Going back to training classes is a good idea as he will meet alot of people and dogs, carry on the training at home so he learns to listen to you. For example teach him the LEAVE command and if he looks like he's going to snap or jump up etc say this word in a firm voice and  once he knows the word it should make him stop what he's doing straight away. when he does this reward him after asking him to come to you, if he doesn't listen then remove him from the room for time out.
Of course you should get him checked out at the vets first but my guess is because he's got away with the little things he's trying his luck,  so this needs sorting out straight away.
It's a good idea to give people treats for him when they come in to your house but for them to ignore him first till he settles then they can call him and reward good behaviour.