It is the first thing any pet owner wants to know before plugging one in, and it is a fair question. The short answer: ultrasonic rat repellents are safe for cats and dogs and inaudible to people — with one exception worth knowing. Here is the detail.
How the sound works
These devices emit high-frequency sound above the range of human hearing. It is designed to be irritating to rats and mice, making a space uncomfortable enough that they do not want to settle there — without any poison, traps or chemicals.
Cats and dogs
Cats and dogs hear higher frequencies than we do, so a few may faintly register the sound. But the output is aimed at the rodent range and is considered safe for them — the vast majority of cats and dogs simply ignore it and carry on as normal.
The exception: small pet rodents
Because the device targets rodents, small pets that are rodents — hamsters, guinea pigs, and pet rabbits (lagomorphs, but similarly sensitive) — can hear it and may find it stressful. If you keep any of these, place the device well away from their enclosure, or in a different room.
Safe to leave running
With no chemicals or fumes, an ultrasonic deterrent is safe to leave plugged in continuously in a home with children, cats and dogs — which is exactly why many people prefer it to poison or traps. The EchoRepel Ultrasonic Rat Repellent is built for exactly this: poison-free protection you can run and forget, as long as you keep it clear of any small pet rodents.