This totally depends on the breed/size/temperment of the animal, also with cats if it's an indoor outdoor cat I would probably thoughroughly discuss this with a client to make sure I have all the details. In general I would probably try and walk the dog away from other people or dogs incase the animal has certain triggers or reactions. I would try and stay gentle and calm around the animal and give them personal space if needed. In terms of environment I wouldn't let a dog off leash if the space isn't enclosed and I would try my hardest to monitor what the dog/cat eats as of not to let them get sick.