The coat color changes as the dog gets older. It is very common for Shih Tzus to develop eye problems at any age, and even more so once they are older. The coat color changes as the dog gets older. It is very common for Shih Tzus to develop eye problems at any age, and even more so once they are older. Most veterinarians will recommend eye drops to assist with any eye irritations. The author then says, 'Dog historians tend to have very strong opinions.'