To the average eye, Lhasa apso and shih tzu dogs might be hard to tell apart, and it might be unsurprising to learn that the dogs have common ancestry. Nevertheless the modern shih tzu and Lhasa apso are separate breeds, and there are subtle differences you can use to distinguish one from the other. Lhasa apsos originated in Tibet but were sent to Chinese emperors as gifts. In China, they were mated with smaller Pekingese dogs, resulting in shih tzus.
Compare the size of the two dogs. As the shih tzu breed was created by crossing Lhasa apsos with Pekingese dogs, shih tzus are smaller than Lhasas. However, Lhasa apsos have a slender frame compared to shih tzus and appear slimmer, even though they are bigger.
Look at the dogs' facial features. Lhasa apsos have smaller eyes and longer noses than shih tzus, while the latter have wider skulls and larger, rounder eyes. According to the American Kennel Club, shih tzus tend to hold their heads high and can appear very regal.
Examine the coat of each breed. Both have long coats that require either daily grooming or frequent trimming to keep at a manageable length. Lhasa apsos have thick coats that consist of dense hair. They come in a variety of colors, from blond to black. Lighter colored breeds often have black highlights on their face and ears. In contrast, shih tzus have a double-tone coat that is thinner and more flowing than a Lhasa apso's.
Compare the appearance of their tails. Both breeds have distinctive long hair on their tails that flows towards the back of their body. Minor differences between the two breeds exist, however. As well as having a thicker coat, the hair on the Lhasa apso tail forms a spiral shape and, because it is coarser, appears more feathered. Shih tzu tails, on the other hand, are more curved and, due to the different quality of their coat, their tails have a wispier appearance than those of a Lhasa apso.