A chain shank is a steel chain with a snap at the end added to a lead rope and run through a halter. It adds “signal” to pressure on the lead rope by causing more discomfort than a halter band when pressure is applied.
When pressure is applied to the lead, the shank puts pressure on the sensitive nasal bones of the horse, greatly amplifying the handler’s signals.
It quickly gets the attention of horses that have been handled incorrectly or do not respond to more subtle pressure. It is often used on stallions that tend to push through handlers and ignore pressure when they are excited.
A chain shank is no more inherently cruel than any other piece of equipment, and is useful as long as it is applied appropriately. It can amplify poor horsemanship, causing confrontation and injury to horse and handler if used incorrectly.
A chain shank used harshly can easily damage a horse’s nose. As with any communication channel between a human and horse, the key is instant release when the horse does the right thing and the use of minimum force necessary to elicit the desired response.
Over the Nose: Run the shank through the left halter ring (on your horse's left side of the face) from outside to inside, looped over the horse's nose, around the noseband of the halter, and threaded through the lower right side halter ring from in to out. Then snap the shank to the upper right ring of the halter (near the ear).
When your horse pushes or pulls against you, apply pressure on the chain as though the horse is causing the pressure themselves. When the horse yields from the pressure, immediately release. Use the minimum amount of pressure necessary to achieve the desired result.
Tips for safety & Success
Using a chain shank is dangerous if you do not know what you are doing. Other than amplifying poor horsemanship, the biggest problem with chain shanks is that they can bind in the halter, preventing release.
I use a chain that is 24"- 30" long. A shorter chain tends to distort the halter and bind in larger horses. If the chain is not attached to the upper right ring, the halter tends to move into the horse's eye when the shank is applied.
Sometimes the chain is placed over the nose, around and under the chin, and attached back to itself. Others run the chain under the chin. I do not use this method. I feel it is counterintuitive and pushes a horse's head up.
A "lip chain" is a chain shank applied over the gums of the upper incisor teeth, under the upper lip. This is the most severe application of a chain, and it can easily cause injury. It may be appropriate in select extreme circumstances on the right horse but it must be used impeccably to be a helpful restraint. It is no substitute for good horsemanship and I do not recommend it.
Never tie a horse fast with a shank over its nose.