Great for my rabbits! Get loads of fur out. Rabbits don't seem too keen and it seems quite rough. I wouldn't recommend for guinea pigs, used it on mine and they did not like it and it did less than a regular brush, far too rough for them! I wonder if this actually takes out more 'healthy' fur and actual 'dead' so I might be concerned if it was over used, so perhaps keep an eye on your pets coat and make sure it is remaining healthy. It has definitely helped through this shedding season and I have less fur over my furniture!