Most Pet Insurance policies only cover the cost of medical conditions or emergencies or accidents with your pet that require immediate care from the vet.
Spaying and neutering doesn't fall under a medical necessity for the pet so most pet insurance policies won't cover that unless you have that as a condition in your policy that they'll pay for the cost of spaying or neutering.
Spaying or neutering costs typically come out of the pet owners own pocket and it isn't really that costly of a procedure and really not worth claiming on pet insurance for anyway.
To have a dog spayed or neutered costs from $100.00 to $200.00 depending on the size of the dog.