Choosing between a collar and a harness for your Rat Terrier depends largely on your individual dog's behavior on leash. Flat buckle or snap collars work well for well-trained Rat Terriers that walk calmly without pulling. A collar width of about half an inch to three-quarters of an inch suits this breed's neck size without being bulky or heavy. Ensure you can fit two fingers comfortably between the collar and your dog's neck — snug enough to prevent slipping over the head but loose enough to avoid restricting breathing.
Harnesses are the better choice for Rat Terriers that pull, lunge toward squirrels, or have any sensitivity in their neck or trachea. A front-clip harness redirects pulling by turning the dog toward you, which naturally discourages the behavior without applying pressure to the throat. Back-clip harnesses are more comfortable for dogs that already walk well but offer less control over pulling. For a breed with strong prey drive, a front-clip design gives you the mechanical advantage you need when a squirrel crosses the path.
Leash length and material are practical decisions that affect your daily walks. A standard six-foot leash made from nylon webbing or biothane provides a good balance of control and freedom. Leather leashes are durable and comfortable in hand but require maintenance. Retractable leashes are generally not recommended for Rat Terriers — the constant tension teaches the dog to pull, and the thin cord can cause burns or cuts if it wraps around legs. The lock mechanism can also fail at the worst moment, giving a prey-driven terrier an unexpected opportunity to bolt.
For escape-prone Rat Terriers, a martingale collar provides extra security. This limited-slip design tightens slightly when the dog pulls back, preventing the collar from slipping over the head without choking the dog. Martingales are particularly useful for Rat Terriers with narrow heads relative to their neck size, which is common in the breed. Some owners use a martingale collar paired with a harness and a double-ended leash for maximum security during walks in high-distraction areas.