Most horse people know that our horses have Chestnuts and not quite as many people know that they have Ergots on their legs. What are they and why do horses have them?
Both chestnuts and ergots are considered by some to be vestigial remnants of the pre-evolutionary leg and foot structure of Eohippus. ‘Vestigial’ refers to something that has lost is purpose as part of the evolution process.
A Chestnut is the harder fleshy growth above the knees on the front legs and just below the inside of the hock on the hind legs of our horses. Some people refer to them as ‘night eyes’. In days gone by it was thought this was how horses see at night, along with other theories such as the Earth being flat... Like finger prints on humans chestnuts are individual in shape and make-up to each horse. The chestnut on some horses grows quite quickly and can be peeled or trimmed back for a more appealing appearance where others barely grow at all. Some horses even nibble and trim their chestnuts themselves! They are a flesh based growth so there is sensitivity to the layers closer to the horse so take care when grooming them. There are some breeds of horses that do not have chestnuts at all. The equine cousins, donkeys and zebras, only have Chestnuts on their front legs.
What is a Ergot?
The Ergot is an even smaller pea-sized callousy type growth on the underside of the back of the fetlocks of a horse. Again, not all horses have all four. Some breeds tend to display more prominent ergots while others have barely any ergot growth at all. They seem more prevalent on horses with feathers. They too can be peeled if ever necessary and also have sensitivity to them closer to the horse. Interestingly the word ‘ergot’ comes from the old French word for a roosters spur, ‘argot’.
So now we know what Chestnuts and Ergots are, why are they there? We know that they are unique to each horse and can be used for identification. It is acknowledged that some horses use the front chestnuts to scratch and rub their faces and it is thought that they are a form of scent glands similar to those found on llamas. Upon closer investigation (with your nose!) you will find they carry a strong ‘horsey’ odour. An old cowboy trick is to put a chestnut of a horse in your pocket and other horses will suddenly become be very interested in you! The ergot serves as an anchoring point to the associated ergot ligament, attaching to the lower pastern. It is also considered that the ergot serves to guide water away from the heel, similar to the function of the feathers.
Whether they got on our horses legs by design or by accident it seems those strange lumps have a purpose! Has your horse got all their chestnuts and ergots? How do you maintain them?