A "sturdy leash" refers to a strong and durable rope or strap that is used to control and restrain a pet, typically a dog, during walks or outdoor activities. Full definition
A strong, sturdy leash for walking your dog. (norsled.org)
Ever puppy will receive a leash and collar, and adult dogs will receive a quick release martingale collar along with a double handle / or other sturdy leash. (angelsonwheels.org)
You will need sturdy leashes, harnesses and / or and carriers to transport your pets safely and to ensure that they can't escape. (oregonvma.org)