Are ultrasonic anti-barking devices safe for dogs?

Yes, they absolutely are. These devices are designed to control dogs without hampering their health or wellbeing. While the sound indicates a dog to cease barking, it creates temporary irritation and nothing beyond. The devices do adjust their frequency as per the dog’s response and hence is in no way harmful for a dog who responds to low frequency or vice versa. The sound is very annoying but completely harmless so you do not have to worry about your dog’s health and wellbeing. 

It is recommended that these devices are only used to control unwanted dog behavior and excessive barking. Do not use it as a method to control barking on the whole as it would be harmful to the dog. If at any time you find these devices cruel for your furry pooch, make sure you look for a suitable option.