For Shih Tzus, a harness is almost always preferable to a collar for walking. The breed's brachycephalic anatomy means their airway is already compromised, and any pressure on the throat from a collar — especially if the dog pulls — can restrict breathing further and potentially cause tracheal damage. Collapsing trachea is a known concern in small breeds, and a well-fitted harness distributes force across the chest and shoulders rather than concentrating it on the neck.
Step-in harnesses and vest-style harnesses are both good options for Shih Tzus. Step-in designs allow the dog to place its front paws through the harness loops while it sits, which many dogs tolerate better than having something pulled over their head. Vest-style harnesses with a wide chest panel provide more surface area for force distribution and often include a handle on the back for quick control in busy environments.
Leash length depends on your walking environment. A standard four to six foot leash provides enough freedom for relaxed neighborhood walks while keeping the dog close enough for safety near traffic. Retractable leashes are popular but carry risks — the thin cord can cause burns or cuts if it wraps around a leg, and the extended distance makes it difficult to react quickly if the dog encounters a hazard. If you prefer a retractable option, choose a tape-style model rated for small breeds.
A flat collar should still be part of your Shih Tzu's wardrobe even if you use a harness for walking. The collar serves as a mounting point for identification tags and registration information, which is essential if the dog ever escapes. Choose a lightweight collar with a breakaway or quick-release buckle, and ensure you can fit two fingers between the collar and the dog's neck for proper fit.