Retractable leash

Known failure modes

• Thin cord burns: a dog sprinting past your leg can cause friction burns or lacerations to the handler and bystanders.
• Spool jams: the brake fails to engage at the worst moment, usually when the dog is heading into traffic.
• Handle drops: if you drop the handle, the recoil drags it after the dog, who then panics and runs further.
• Sudden-stop neck injury: at 20+ feet the dog hits the end at sprint speed; on a collar this can injure the cervical spine.
• No mechanical advantage for emergency recall, you can't pull a 60 lb dog back against a thin cord.

If you choose to use one anyway

1. Tape-style (flat ribbon) over cord-style, far less burn risk.
2. Always on a harness, never on a flat collar or any neck-pressure tool.
3. Lock it at a fixed length when near roads, other dogs, or people.
4. Never use with a head halter or a dog who lunges at triggers.

Why it matters

For most dogs and most environments, a 10–15 foot fixed long-line on a harness gives the same freedom with none of the failure modes. Retractables are appropriate, if at all, for trained, non-reactive dogs in open spaces with no traffic.