DIAGNOSIS OF DISTAL TARSAL AND
PROXIMAL METATARSAL LAMENESS
Michael Schramme
VetAgro Sup, Campus Veterinaire de Lyon, Marcy L’Etoile, Rhones-Alpes, France
Introduction
Proximal plantar metatarsal pain can be defined as lameness that improves
following anesthesia of the deep branch of the lateral plantar nerve or other
forms of subtarsal anesthesia. Proximal plantar metatarsal pain appears to
have become the most commonly diagnosed cause of hindlimb lameness in
Sporthorses, even more common than distal tarsal joint pain. While the
diagnosis of proximal suspensory desmitis (PSD) in Sporthorses appears to
have increased in recent years, the reasons for this remain poorly understood.
Improved recognition not only by veterinarians but also by equestrian
professionals certainly has played a role. Modern training demands, regimes
and surfaces may also contribute. Predisposing factors have been identified
as dressage training not only at advanced level but also at lower, non-elite
levels, straight hocks and hyperextended fetlock conformation.
History and Clinical Signs
Suspensory desmitis is believed to be caused by an accumulation of repetitive
strains within the suspensory ligament and its origin. Strains are thought to be
particularly high in well-moving dressage horses especially during increased
collection required for more advanced work including such movements as
piaffe, passage, canter pirouettes and advanced diagonal placement. PSD is
frequently, though not always, associated with a straight hock and
hyperextension of the MCP/MTP joint. It is not always clear if this appearance
is a primary risk factor or a secondary postural change due to loss of strength
of the stay apparatus in affected horses.
The reason for presentation of the horse to a veterinarian may vary from
subtle loss of performance to marked, unilateral lameness. Loss of
performance during ridden work may present itself as bilateral stiffness, loss
of hindlimb impulsion, difficulties in transitions, change in contact with the bit,
or resistances, evasive behavior, or reduced power when jumping. Unilateral
lameness may cause resistance to lateral exercises, flying changes or canter
pirouettes. Early lesions may go unnoticed by even the most skilled
horseman, because the rider or trainer is aware of only a vague problem that
the horse warms out of fairly quickly. With bilateral hindlimb injury the rider
may complain of loss of power. Exercise continues, and the injury eventually
worsens to the point of causing enough damage to produce obvious
lameness. Lameness may be mild with an insidious progression or severe
with an acute onset. Bilateral lameness is common and can be mild to
moderate in degree. It would appear that dressage horses tolerate hindlimb
PSD less well than show jumpers or event horses.
15-‐18
February
2016
East
London
Convention
Centre,
East
London,
South
Africa
164