What happens when your dog accidentally swallows your pantyhose?

You can take him to a vet, but he'll tell you what I'm about to share: this too shall pass. As with all critters, what goes in must come out. Pantyhose being made of synthetic material is not digestible, so will exit much as they entered. That isn't to say precautions shouldn't be taken. You'll need to monitor your dog's stools. He's not likely to pass it in a bunch, but likely more strung out. It would be uncomfortable and dangerous for him to trail around half of your knickers dangling from his anus. So, keep a pair of scissors handy. When you find strings hanging unpassed, clip them off. Be careful not to pull or you can knot up his bowels and cause serious injury. Eventually, the last of it will move along.