Ask Alys: is there a dog-resistant alternative to grass?

Our gardening expert has the answer to all your garden-related questionsThe onslaught of my two labradors means I have paved over most of my lawn, but the remaining grass turns nasty even with frequent cleaning and raking. Can you suggest tough, flat, non-grass groundcover?
Little will survive life as a dog run without some wear and tear. First, try reseeding with a grass mixture tolerant of heavy foot traffic. Two types might work – Superstar: Back Lawn mix from The Grass People; and Lawn