Flexural Deformities from Farrier`s

Contracture of the Deep Digital Flexor Tendon
There is often confusion between the hoof pastern axis (HPA) and hoof angle. The HPA is the alignment of all three phalanges and the (dorsal) hoof wall). It is normal for a foal to have an HPA angle of 60 degrees or even 65 degrees to the horizontal. This drops to approximately 50- 55 degrees in the mature horse. A high angle (60 degrees or more) does not necessarily mean that the foal has AFD or club foot. When contracture of the deep digital flexor tendon (DDFT) occurs the coffin joint is flexed and the HPA is broken forward.

Characteristic signs of AFD involving the DDFT only are:

1. A stilted gait
2. Standing on the toe only - heel clear of the ground
3. Excessive heel
4. Broken-forward hoof pastern angle (HPA)
5. Excessive wear at toe
6. Concave dorsal wall

Club foot is the final manifestation of AFD involving relative contraction of the DDFT. It must be clearly understood that club foot is secondary to the condition and is not the cause. A club foot has similarities to a chronic laminitic foot and presents the farrier with many of the same bio-mechanical problems. The aim of farriery is to return the foot to a normal alignment and shape in order that the horse does not have a chronic club foot which is a permanent source of lameness.

The characteristic signs of a club foot are:

1. HPA broken forward
2. Dorsal wall angle at 65 degrees or greater
3. Concave dorsal wall (not 'foal foot')
4. Heels growing faster than toe
5. Coronary band approaching a horizontal position
6. Growth rings diverging at the heels
7. Foot narrower than normal (than other foot)
8. Solar view shape more oval than round
9. Lateral clefts more vaulted than normal
10. Sole forward of frog apex flat or convex
11. Atrophied frog
12. Separation of white line/poor hoof quality at toe
13. Lateral radiograph shows distal phalanx rotation in relation to hoof capsule and middle phalanx with remodelling and lytic changes including the dorsodistal border.  [...]