- For the actor, see Macaulay Culkin.
A caulkin (or caulk; US spelling "calkin" or "calk") from the Latin calx (the heel) is either:
- a typically blunt projection on a horseshoe (either forged, welded or brazed onto a horseshoe), or
- a removable caulk or (usually) blunt spiked cleat placed into a special "one-way" hole where it cannot fall from the sole at the toe of the shoe.
Traditionally, the prongs of an elongated horseshoe (commonly not more than 1.75 inches or 45 mm) have tips bent at an acute angle opposite to the surface attached to the horses' hoof. Traditionally, a farrier employs a forge in hot-shoeing to heat the two heel prongs to red hot and bends them by hammering prongs over a right-angle to bend into an acute angle. Occasionally, another caulkin is on the toe of the shoe and integrally formed in the initial forging process (see 3 caulkins in image at top).
For a horseshoe built as a concave caulk and wedge shoe, the 2 prongs differ:  one prong ends with a caulkin, and the other prong ends with a wedge (with both facing downward to the ground). That caulk/wedge horseshoe is a traditional British hunting shoe, and it has been used to provide the horse with a sure-footed grip when working at a fast pace over uneven ground. The shapes of the caulkin and the wedge have been designed to provide hoof traction, meanwhile ensuring the horse's safety is not compromised. The caulk/wedge horseshoe design has been recognised by the Worshipful Company of Farriers as being an appropriate specimen horseshoe to be used for the diploma exam.
- ↑ 1.0 1.1 : "Know Foot Know Horse", knowfootknowhorse.com, 2008, webpage:
- KnowFKH-20 (see top photo on webpage).
- ↑ 2.0 2.1 : "Farrier Competition Results 2008",
- Forge and Farrier, UK, 2008, webpage:
- ↑ 3.0 3.1 3.2 "Know Foot Know Horse - Concave Caulk and Wedge", knowfootknowhorse.com, 2008, webpage: KnowFKH-226 (see caulkin/wedge horseshoe photo on webpage).
- Horseshoes.com , accessed August 4, 2008.
- "Forge and Farrier", , accessed August 4, 2008.
- Farrier Source , accessed August 4, 2008.
- Historical development of the horseshoe 1891 Scientific American article from Project Gutenberg