LAMENESS ISSUE

General Appearance

Shortened cranial (forward) phase to stride; lengthened caudal (backward) phase

Episodic and sustained hyperflexion with concurrent abduction (holding the affected limb out-and-away from the body)

Excessive spasmodic hyperflexion of one or both hindlimbs during movement

Fixed pelvic limb extension followed by sudden abrupt hyperflexion

Cause of Gait Abnormality

Functional shortening of the cranial (forward) phase of the stride due to mechanical restriction of fibrotic/ scarred semitendinosus/ semimembranosus (hamstring) musculature along the back of limb

Underlying neuropathy and/or episodic muscle cramping resulting in prolonged flexion/ abduction of affected limb

Neuropathy resulting in lateral digital extensor muscle hyperactivity

Failure of the medial patellar ligament to disengage from the medial trochlea of the femur, thereby disallowing normal flexion of the hind limb

Gaits Most Affected

Walking

Standing, backing

Walking, turning, backing

Walking, downhills

Frequency of Abnormality

Every Stride

Sporadic

Every Stride

Sporadic

Also Look For:

Goose Step

Concurrent Tail Elevation

Laryngeal Hemiplegia ("Roaring")

Visible or Audible "Pop" to Limb at Initiation of Flexion

You Probably Won't See:

Hyperflexion of Affected Limb(s)

Visible or Audible "Pop" to Limb at Initiation of Flexion

Visible or Audible "Pop" to Limb at Initiation of Flexion

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SIGNATURE TRAITS

Goose-stepping (the foot moves backwards just before impact and slaps onto the ground surface abruptly)

Horse holds up affected limb up for an extended period of time

Horse immediately returns affected limb back to the ground from the flexed position

Horse may drag affected hind limb behind the body while the patella is "locked" and the hind limb is fixed in extension. An obvious "snap" or "pop" of the hindlimb (most easily seen at the level of the hock) occurs at the moment the medial patellar ligament disengages and the limb flexes from the extended position

See What This LOOKS LIKE!

Fibrotic Myopathy

Shivers

Stringhalt

Upward Patellar Fixation

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