As part of the breed standard, the American Kennel Club requires the Shih Tzu's coat to be "luxurious, double-coated, dense, long and flowing," its temperament "outgoing, happy, affectionate, friendly and trusting towards all." But achieving that splendid coat and cheerful personality will be impossible if a Tzu is feeling so itchy it can do nothing but scratch itself. Even if you don't plan to show your little lion dog, it should still look tidy, feel comfortable and be well. The key to stopping your Shih Tzu from scratching is to identify what is causing the irritation and take steps to alleviate it.
Inspect your Shih Tzu's skin and fur for evidence of fleas, which can cause a great deal of discomfort. If your dog suffers from a flea allergy, it will be even more miserable--just one flea bite can cause days of misery. In the article "Stop Itching!," Dr. Domenico Santoro, a dermatology resident at the University of Illinois College of Veterinary Medicine in Urbana, says dogs with a flea allergy have very specific symptoms: "hair loss, scabs and flakiness, especially localized at the base of the tail, thighs and abdomen." If you find any evidence of fleas or suspect your Tzu is suffering from a flea allergy, treat it with a topical or oral flea control. Because these are poisons, however, use only those that your veterinarian recommends.
Take your Shih Tzu to the veterinarian and ask her if she thinks it might be a good idea to take a skin scraping. The Shih Tzu breed does tend to be susceptible to yeast infections of the skin, according to PetEducation.com, and this test can check for it, as well as for bacteria, mites or other parasites. If the vet thinks a skin scraping is advised, she will use a scalpel blade to remove a bit of skin from your dog, then examine the sample under a microscope. Should she spot a problem, your vet will prescribe the necessary treatment. Keep in mind, though, that yeast and bacterial skin infections often manifest as a secondary symptom of a primary problem, which will need to be determined and addressed.
Ask your veterinarian if your itchy Tzu might have food allergy dermatitis. Food allergy is the third most common allergy in dogs, after flea and environmental allergies, and can develop after repeated exposure to the offending ingredient. Unlike people, blood tests to determine the problem food is not reliable in dogs. The only way to find the source of the reaction is through an elimination diet, a prescribed homemade or commercial diet that contains one protein and one carbohydrate to which your Shih Tzu has never been exposed. You will feed the dog this prescribed diet and water only, eliminating all other food sources--including treats, chews, flavored toys, medications, supplements and toothpastes--for up to three months. If there is a marked improvement in symptoms, your vet will instruct you to return your dog to its previous diet and treat habits. If symptoms recur within 14 days, a food allergy is confirmed. At this point you will return your dog to the prescribed diet until the symptoms resolve, then add ingredients to the diet, individually, for 14 days each. Any ingredients that prove to be the problem must be eliminated from the dog's diet indefinitely to keep your Shih Tzu itch-free.
Ask your veterinarian if she thinks your Shih Tzu might have atopy. Atopy, also called canine atopic dermatitis, occurs when a dog becomes sensitive to environmental allergens, such as plant pollen or mold, and the Shih Tzu is a breed predisposed to developing it, says "The Merck Veterinary Manual." The symptoms of atopy can be calmed with antihistamines, anti-inflammatories and shampoos. But because most airborne allergens can never be completely avoided, the only way to fully address the condition is for your vet to run allergy tests on your dog and provide immunotherapy--hyposensitization, desensitization or allergy vaccines.