Which isn't the right answer (and nor is ignore it and do nothing)
I will expand abit on that quote.
The answer I was looking for is to begin a controlled brake keeping the lorry under control. This doesn't mean slam the brake pedal to the floor and hope the ABs looks after the whole lot. It involves progressive braking and selecting of a low gear.
Its a progressive brake to allow the people behind to see and brake themselves. And also it starts the braking process which can then be turned into an emergency stop if there is a person chasing the cat to try and catch it.
You can actually be done for dangerous driving in an artic for doing a emergency stop for a cat running across the road.
At low weights they stop alot quicker than a car and alot quicker than a bus. Did you know that if you do a emergency stop infront of a bus you have to wait and confirm that no injurys have been sustained on the bus? Otherwise you are leaving the scene. If you have a school run tail gating you (you proberly won't even know about it. If you can't see the mirrors we can't see you) They will just go straight into the back bars which won't even bend, the back of the trailer will be lifted and the fire brigade will then spend the next 2 hours trying to cut out 2 kids and save the legs of the driver.
There are several things that can happen during a hard brake on a HGV which are potentially lethal.
1. The trailer decides its going to over take the unit ie (jack knife) you then have 45ft of trailer swing round at 25mph across the road which will mount the pavement and take out all other road user's in the way.
2. A tyre blows out. 120psi propelling rubber shrapnel onto the pavement.
3. The load cuts loose. In theory you should have strapped it down so that it should stay on if you tip it on its side. But things fail in service.
4. Carrying pipe or sheet metal. The load slips and 35ft of pipe comes straight through the trailer end through the cab and bounces down the road. Or the sheet metal does the same and it takes 10 mins for you to die depending if you have enough gumption to throw yourself sideways to break the suction keeping your guts in.
A full blown emergency stop in an artic is akin to a forced landing in a plane. If everything works it all ends with happy faces. If one thing is wrong it all ends in tears.
Which is why the lorry drivers get so wound up when people nick there safety zone by nipping infront coming up to a roundabout or Motor cycles deciding that the half lane you have left on the inside to turn left is a perfect size for them. And from experence it stays with you for ever when you run a MC over and he looses his leg.
BTW even in a car I wouldn't do an emergency stop these days for a cat. Even though I haven't been in an artic for 2 years now you can't stop the reflexs working. Still looking 500yards ahead, still braking with the gear box, still double declutching and of course being a bastard and pushing in on roundabouts and taking every oppertunity to piss taxi drivers off.