6) Tapeworm
This is not as rare as you would expect in some dogs and even Shih Tzus can experience tapeworms. These parasites will essentially suck all the nutrients and vitamins out of the foods your dog eats, which can lead to a loss of weight. Monitor your dog’s eating habits and take note of anything out the ordinary.
There are other issues that could cause your Shih Tzu to lose weight, such as liver disease or old age. If you're unable to identify the cause of your dog's weight loss, make sure to bring your pet to the vet as soon as possible. Even some of the biggest issues can be easily corrected or treated if caught early on.
