Have you ever seen your dog sit down and scoot his butt along the ground? Or trying real hard to chew his butt.
Well theres several reasons why that might be happening.
Dogs have glands just inside their anus opening that can fill full of fluids and become impacted if not emptied or relieved.
Wild dogs normally emptied these glands by marking their territory and roaming. But our dogs have become house dogs and many don't mark or roam. So their marking glands can fill full and create all kinds of problems .They itch and burn hence the scooting trying to at least give them temporary relief.
You can help them yourself by putting on a surgical rubber glove and inserting your finger to "milk the glands on each side. Which by the way smell really obnoxious or take him to the vet and let them milk them and aleveate the problem.
In reading about this I also found a really good product to use called "anal glandz" made by pet alive . It will take away the itching and break up impacted glands. I'm not saying not to take your dog to the vet don't let him suffer but this product can help and perhaps you won't have to take your dog to the vet for this problem as often.
Another reason anal itching ocurrs is worms always have the vet check for worms they need to be eliminated as soon as possible. tapeworms , and others can cause these symtoms.
Also yeast infection can cause itching I feed our dogs yogurt the plain kind with no fruit or sugar, natural it balances the friendly bacteria in the intestines and creates a healthy environment. Just like for humans I find my dogs love it
You can find the "anal glandz" at http://www.petalive.com/ it doesn't take much and your poor itchy friend will feel better