Weird horse anatomy – hoof and leg edition!

 

Horses are magical creatures, full of weirdness. And not just in some of their quirks, as horses have some unusual features in their anatomy and physiology.

• The frog of the horse is loaded with blood vessels! When a horse steps, the ground pushes back on the frog. All of those vessels, the frog itself, and the underlying pad of the hoof squeezes the blood out of the digital cushion. This counteracts gravity and lets your horse’s blood flow back up the leg.

 

The frog is magic – it pumps and it sweats!

• And then there’s sweat. Horses are some of the sweatiest creatures around, and they have two types of sweat glands. Apocrine sweat glands in the horse are responsible for thermoregulation and secrete sweat into the sac of the hair follicle. Eccrine sweat glands secrete sweat directly to the surface of the skin. In horses, the only eccrine sweat glands they have are on their frogs. Yes, the frogs. Makes total sense, right?

• A horse can also regulate the blood flow into the hooves. The process is arteriovenous anastomosis, which is a system of shunts inside the hoof capsule. Cold hooves can increase the blood flow to the hoof! This process might be damaged in the horse that has had a bout of laminitis.

• Some of the closest relatives to horses are actually rhinos and tapirs – because they are all perissodactyls! This means they have an odd number of toes. All other perissodactyls are extinct.

Snooze time.

• So how does a horse stand and snooze at the same time? The hind leg sling helps here. The stifle is able to rest in a cocked position, with the other leg maintaining the weight. The cocked leg can then be ready to go (kick, run, stomp a fly) at a moment’s notice. The ligaments around the hip and hind leg allow the resting hind leg to be supported by a sling. Cool, right?

Now you know!