Clean them out?? 
You need someone to repair them, prob using fillers and airbrushing the colour and topcoat back
Not worth it if the dog is still there though 
My sentiments exactly Dave.
We have a policy of not doing repairs for pet owners anymore. Fed up with the call backs alleging failure of repair carried out (the little sods back on it again causing havoc with their claws). Had one once who caled me back and said that 'the dog doesnt go on the leather whatsoever'...all saying this while the dog was laying ON the sofa - doh!
Get a pro in to do it Lavinia - if he's willing?