As a rescuer, I have tried a lot of probiotics with varying results with many different animals. I have found that Synbiotic 180-s has been the best I’ve used by far! Lactose free and a very fine powder, it dissolves quickly into kitten milk and makes the transition from mum's milk to formula so much kinder on baby kitten's tummies. It is also super well tolerated by guinea pigs, helping one of the sanctuary guinea pigs avoid all complications associated with post-surgery antibiotics. I have happily recommended Vetafarm Synbiotic to many people and will continue to do so!