Hi, I'm a long time reader of posts but this is my first reply. As a dog trainer I am horrified at the idea of holding a dog's nose in the poo and hitting him -- the equivalent of shoving a child's head in a toilet after an accident! You need to get an enzyme based cleaner to get rid of the smell of dog poo and urine on your pegola -- an ordinary household cleaner won't work as it contains ammonia which smells like urine. Try positioning your dog's bed and water bowls under the pergola, near the areas that have been fouled the most. When you take your dog outside, take him on a lead to the area you want him to use and give him a food treat when he goes in the correct place and tell him how wonderful he is. (Rewards work better than threats or punishment!) check this website www.dogstardaily.com for more advice about toilet training. cheers