Yes, a dog can sleep in a crate with a cone. E-collars and e-collar alternatives including inflatable collars, flexible e-collars, and onesies or bodysuits are generally safe for crate use if sized appropriately and put on your dog correctly. Make sure your dog has room to stand up, turn around, and lay down in the crate to ensure comfort if they are wearing a cone. If your dog is at risk of popping an inflatable e-collar or chewing parts of a dog cone, talk to your veterinarian to ensure safety before using the product in your dog’s crate.