Any breed can succumb to ill health but each breed has it’s own weak areas. Having your dog under the care of a good vet is absolutely essential. Shih-Tzu’s while small are very sturdy. Puppies are often prone to having umbilical hernias, this is due to the comical underbite of the breed and the mother can often not get a good bite on the puppies umbilical cord so a small hernia may well be the result. This is just a small lump on the puppies tummy. Sometimes these shrink over time but if they don’t go then simple surgery will resolve the matter.