Bred for palaces, not for ponds
The Shih Tzu was developed purely as a companion, a small dog whose work was sitting with people indoors, and nothing in that history prepared the breed for water. Short legs paddle inefficiently, the body rides low, and the flat face with its short muzzle sits alarmingly close to the surface, so even a willing Shih Tzu takes in splashes around the nose and eyes that a longer-faced dog never notices. Many Shih Tzus do enjoy being in shallow water on a hot day and will paddle about happily at standing depth; the distinction that keeps them safe is between that and swimming out of their depth.
The coat and the eyes complicate everything
A Shih Tzu in full coat carries long hair that drags heavily when soaked, tangles as it dries, and holds water against the skin, while even a dog in a short pet clip has a dense coat relative to its size. The breed's prominent eyes are easily irritated by chlorinated water and lake grit, and a face that rides low collects both. Water in the ears and damp skin folds after a paddle are familiar Shih Tzu troubles if drying is rushed. Together these quirks mean the sensible Shih Tzu water programme is shallow, brief, face-dry, and followed by real grooming rather than a shake and a towel tossed over the back.
Paddling, set up properly
Use a shallow entry where your Shih Tzu can walk in and stand comfortably, such as a purpose-made dog paddling area, the top step of a pool under your hands, or a very gentle shoreline, and stay close enough to lift the dog out in one motion. Keep sessions to a few minutes, let the dog choose to enter and leave, and watch the face: a Shih Tzu whose chin is dipping and whose breathing is growing audible is at its limit, whatever the legs are doing. For an adventurous dog, a small life jacket fitted to a broad little chest adds flotation that keeps the face higher, but it never converts deep water into a safe place for this breed.
After the paddle: face, eyes, ears, coat
Rinse with clean water, paying attention to the face and around the eyes, and dry the coat thoroughly, combing as you go if the hair is long, since Shih Tzu hair mats fastest while it dries in clumps. Dry the ears and check the eyes for redness or squinting that persists, which deserves a call to your veterinarian, as does scratching at ears into the next day. Take breathing seriously in this flat-faced breed: repeated coughing after a paddle, noisy breathing at rest, or a dog who seems weak or distressed after swallowing water needs veterinary care the same day, and urgently if breathing is laboured.
One rule, shared by everyone
Shih Tzus are often passed between adoring hands, at home and at gatherings, and each new holder may assume a quick dip is a treat. At a gathering, a relative holding it can view that profile through Family Sharing in KinsLe, once you have given the relatives you pick access, before suggesting any water play.