7. Shih tzu
Image: Beverley Goodwin/Flickr
Shih tzus tend to become jealous of babies and toddlers, so protect your other little loved ones from their insecurity. Even though they’re only up to 11 inches and 16 pounds, they may not be the best fit for families with small kids who don’t know how to act around dogs (or if your dog isn’t properly obedience-trained).