Pet sitters that you hire should be insured. If something should happen to someone that comes near to a pet that doesn't want them to, and your pet reacts, you could be liable if the pet sitter does not have the right insurance to protect them from this type of situation.
When you have more than one pet, finding a pet sitter that will take them all is important. You may find this to be challenging if you have more than one type of pet, such as a dog and cat. Yet, you'll be surprised at what most sitters will do to make sure your pets are happy.