To help alleviate stress on both the puppy and another dog or cat, keep the older dog or cat in a different part of the house for say 45 minutes and let the puppy roam around and smell everything in the house. Take puppy outside to potty and put the puppy in its crate for a nap. Then let the older dog or cat out to roam and smell the puppies scent. When Pup awakes from its nap take puppy directly outside to potty. Then back inside to meet the older dog or cat, let them approach each other and just stay close by to watch them. The puppy will want to go up to the dog or cat and smell them. A slight snarl from the older dog is normal as the older dog is giving a warning not to get too rough with them. You will start to notice the difference between a snarl and a mean snip. Cats nay take a little longer to warm up to the puppy.