True separation anxiety is a medical issue. Your vet can prescribe anti anxiety drugs. But, true separation anxiety usually involves what Greyghosts describes: thrashing, drooling, broken teeth, bloody paws from scratching, stuff like that.
Chewing up the blinds sounds like a bored dog that might be a bit anxious, but, without more information, I'd doubt it's true separation anxiety. How much exercise is the dog getting? Do you leave anything for the dog to do? Toys, a frozen, stuffed kong, stuff like that?