Equine Leg Anatomy: Part Three

Part Three: The Hoof

You've probably heard the old adage "no hoof, no horse" and maybe even had occasion to experience for yourself when your horse became 3-legged lame with an abscess or lost a shoe.  Horses place a lot of weight on their feet while essentially standing on their tiptoes and weighting their fingernails.  It's no wonder some pain there or an imbalance can cause such a big difference to their gait and soundness!

The pastern and bones of the foot

CLUB FEET

Club feet are abnormally upright hooves.  They typically occur in front feet and often with one hoof upright and the other hoof at a lower angle than is normal.  Club feet can be the result of tightness of the Deep Digital Flexor Tendon due to nutritional imbalance where the bones lengthen quicker than ligaments. It can also be an imbalance caused by horses adopting a habitual stance while grazing of always putting the other foot forward. There is even a genetic component and some family lines in Arabians seem prone to club feet. Sometimes this condition can be gently and gradually corrected by trimming and shoeing to even out the two front feet. Occasionally in extreme examples, surgery may be required in which vets cut the inferior check ligament to allow the heel to drop normally. 

LAMINITIS

The bones inside the foot are connected to the hoof capsule by laminae, interlocking folds on sensitive soft tissue on the outside of the bone (P3) and the inside of the hoof capsule.  These sensitive laminae can become inflamed, swollen, and weak by grain overloading (like when a horse gets loose and eats a lot of grain), too much fresh spring grass after not being exposed to it all winter, insulin resistance or illness caused by infectious disease. This is called foundering, and is very painful to the horse.  It can happen repeatedly in the case of a horse with insulin resistance where any slight changes in sugar-intake can bring on an episode or it can occur in isolated incidences where triggered by stresses on the body.

Founder can be mild and treatable or may necessitate euthanasia, depending on the severity. Extreme cases may cause the bone of the hoof (P3) to drop within the hoof capsule or to rotate downwards now that it is no longer properly supported by the laminae (see above).  

A horse can even lose it's hoof capsule entirely and shed it like a snake shedding its skin, although this is mercifully rare.  

Hoof capsule - see folds of laminae

Hoof health is very crucial for your horse's well-being. Be sure to keep your horse's diet managed carefully and introduce your horse gradually to green grass in the spring & summer.  If your horse seems ouchy on his or her feet, call a vet.  They can help you determine whether the horse has an abscess (an infected area within the hoof capsule) which though painful is very treatable, or whether it is foundering.

Next installment: Hocks & Stifles

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