Do ultrasonic pest controls hurt rabbits?

No evidence suggests that ultrasonic pest control devices harm rabbits or other household pets. These devices emit high-pitched sounds inaudible to humans but are supposed to be unbearable for pests like rodents and insects. While some studies on the effectiveness of ultrasonic pest control devices have shown mixed results, there are no known harmful effects on rabbits.

What type of rodent is best for a child with allergies and asthma?
My rabbit just ate a small piece of onion lying around. she seems to be acting fine at the moment but I heard that onions can very harmful rabbits and maybe even poisonous. what should do?