Page 117 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 83

problems in Thoroughbred racehorses in one study.
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Additionally, injury to the palmar soft tissue structures of
VetBooks.ir ing that it may not be a strictly genetic influence.
the carpus may contribute to this conformation, suggest­

dorsal (Forward) deViation oF the CarPus (BuCked knees
or knee sPrung)
This condition may also be called “goat knees” or “over
in the knees” (Figure 2.13). It is generally believed that
“bucked knees” is a less serious problem than the calf‐
knee condition and may protect against carpal disease in
racehorses. However, severe dorsal deviation may be
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more dangerous for the rider because the horse’s knees are
on the verge of buckling forward. Forward deviation of
the carpus may be caused by contraction of the carpal
flexors (i.e. ulnaris lateralis, flexor carpi ulnaris, and flexor
carpi radialis) in young horses and may place increased
strain on the extensor carpi radialis and the suspensory
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ligament. Congenital forms are nearly always bilateral
and may be accompanied by a forward knuckling of the
fetlocks. The condition is often present at birth and usu­
Figure 2.21. Base‐wide, toe‐out conformation.
ally disappears by 3 months of age if it is not severe. One
This is an undesirable characteristic referred to as “plait­ study documenting the variations in conformation in
ing,” because it can produce interference and stumbling Swedish Warmblood horses found that considerably more
when the advancing limb contacts the one placed in elite sport horses were “buck kneed” than “calf kneed,”
front of it. Plaiting tends to be seen more commonly in while the reverse was true in riding school horses. 22
the hindlimbs than the forelimbs.
lateral deViation oF the CarPus (Bowlegs, CarPal Varus,
Palmar (BaCkward) deViation oF the CarPus (hyPerextended knees, or Bandy‐legged ConFormation)
CalF knees)
Carpal varus is an outward deviation of the carpus
Backward deviation of the carpus (back at the knee) is (or inward deviation of the distal limb) when viewed
thought to place increased stress on the palmar soft tissue from the front of the horse (Figure 2.22A). It may be
structures and increase compression on the dorsal aspect accompanied by a base‐narrow, toe‐in conformation.
of the carpus (Figure 2.13). Backward knee conformation This condition increases tension on the lateral surface of
is thought to make horses working at speed more suscep­ the carpus and compression on the medial surface of the
tible to carpal injuries, but this is not widely accepted. carpus and carpal bones (Figure 2.18). This deviation
Hyperextension of the carpus is not the only reason for may be correctable in young horses, but growth of
carpal injuries; long toes were associated with carpal the knee is thought to reach a plateau at approximately

A B
Figure 2.22. Examples of abnormal carpal conformation as compared to Figure 2.11. (A) Carpal varus or bowlegs. (B) Carpal valgus
or knock knees. Some degree (<5°–7°) of carpal valgus is considered to be within normal limits in most horses.