Page 63 - May 2018 Speedhorse

It is very important to evaluate the horse on smooth, firm ground if possible and to keep the horse’s speed moderate and steady to decrease variations in gait caused by external factors, particularly if the lameness is mild or subtle.
easier to observe. In addition, the faster speed of the trot, compared to the walk, increases the stress on the horse’s limb and typically exacer- bates the lameness.
In the front limbs, the horse takes weight off of the affected leg and carries more weight on the sound(er) leg and this body motion is often transferred to head motion. The head
can be thought of as a weight that is up on the lame leg and down on the sound (or less lame leg); this results in an observable head nod. It is typically easiest to observe the down movement of the horse’s head, neck, and body as the horse absorbs the concussion of increased weight bearing on the sound limb. This is because some horses with subtle front limb lameness do not have an obvious head nod and do not have an upward movement of the head. In these horses, the examiner observes the increased concussion through the shoulder, neck, and leg as the horse lands on the sound limb and ab- sorbs the increased concussion in his/her whole body. On hard surfaces, the lameness can be heard as well as seen because the foot of the sound leg makes a louder sound as it contacts the ground. Some lameness problems cause
the horse pain as the affected limb is advanced forward; this results in a shortened stride and subsequent lower arc of foot flight. The horse may not flex the leg normally and will swing the leg out or in to avoid the normal action required to break squarely over the toe.
Hind limb lamenesses are more difficult for the inexperienced eye to see. The horse
that is lame behind will land heavier on the sound limb and will unweight the painful (lame) limb. In some horses, uneven concus- sion between hind limbs results in a “hip hike” where the horse’s hind end stays higher when the lame leg hits the ground and goes down more when the sound leg hits due to the horse taking more weight on the sound limb. This
is observed when watching the tail head or the top of the pelvis as the horse trots. More often, you will see the pelvis “move down” when the sound limb is on the ground/as the lame limb comes off the ground. This can be observed by watching over the top of the pelvis. Differences in concussion can also be seen by watching the fetlocks; the fetlock typically drops lower on
the sound leg and the horse also spends more time on the sound leg. Thus, the fetlock will drop less on the lame leg because the horse is taking less total weight on that leg. These gait abnormalities give the horse the appearance of “hopping” off of the lame leg onto the sound leg, especially with more obvious/severe lame- nesses.
Hind limb lameness is frequently character- ized by a shortened anterior phase of the stride (the lame limb is not carried as far forward as the opposite limb) and sometimes a toe drag
as the limb is advanced. This is the result of pain on flexion of the limb where the horse will alter his gait to minimize flexion. When the horse is very lame in the hind limb, there may be also be a head nod present which can make it look like it’s a front limb lameness. Horses with moderate-severe hind limb lameness will take weight off of the lame hind limb when that foot hits the ground and appear to lunge forward onto the opposite front leg as the lame hind limb contacts the ground.
For example: At the trot, a horse with severe right hind limb lameness will be nodding down on the left forelimb; this can be confused with a right front limb lameness.
Some hind limb lameness problems are quite subtle; the lame leg can be found by tak- ing a few minutes to study the horse’s gait to determine which foot the horse is landing on with the most force by observing the above- mentioned changes.
Lameness evaLuatIon
Lameness evaluation begins with observing the horse at rest, standing quietly if possible.
It is important to see how the horse chooses to stand, but then to also have the horse stand as square (all feet on the corners of an imaginary rectangle) as possible so you can assess side- to-side symmetry. During this initial phase of the exam, any swellings on the horse’s legs, en- larged joints, or abnormalities in conformation can often be observed without touching the horse. Palpation of the limbs, neck and back can be done before or after the motion exam; this is based on the preference of the veterinar- ian. Hooftester evaluation also needs to be per- formed, and this can be done before or after the
When testing for lameness, a hooftester evaluation is done by applying pressure to the sides of the feet to check for sensitivity or pain.
It can be performed before or after a motion exam, and then the horse should be checked for
gait deficits.
motion exam; again, based on the preference of the veterinarian. The horse is then evaluated for gait deficits, first at a walk and then at a moderate, steady trot. It is very important to evaluate the horse on smooth, firm ground if possible and to keep the horse’s speed moderate and steady to decrease variations in gait caused by external factors, particularly if the lame- ness is mild or subtle. Evaluation of the horse for lameness is not always easy, especially if multiple limbs are involved or if the lameness is subtle.
The lameness evaluation should also involve trotting the horse in circles, as this will often exacerbate a baseline lameness or may produce a lameness that was not present in a straight line. Circling often makes the lameness on
the inside limb more noticeable, although oc- casionally lameness on the outside limb is made worse by circling the horse. When the horse
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