|When used to treat complicated or unresponsive
laminitis, deep digital flexor tenotomy remains the most
cost-effective salvage procedure available. Patients with
laminar damage sufficient enough to be considered for tenotomy
have lost all potential for future athletic ability. Tenotomy
is performed as a salvage procedure so the animal can be used
as a broodmare or possibly as a pleasure horse. ( Turner,
O'Grady, et al 1993) (Eastman 1998 )
Though the indications for a tenotomy will vary with
individual cases, there are two basic guidelines. Tenotomy is
- The distal phalanx has rotated more than 12o in the
first 30 days of the syndrome
- The extensor process is displaced distally as much as 1
cm during the first week of the disease.
Other candidates for tenotomy include unresponsive cases
with massive laminar damage, or horses with chronic laminitis
in which other forms of foot support and/ or heel elevation
have been unsuccessful.
Following tenotomy, the distractive forces exerted by the deep
digital flexor tendon are eliminated, and the tension on the
apex of the distal phalanx is relieved, thus allowing
increased blood flow to the laminae and solar corium. There is
also an increase in the depth of the sole, resulting in
immediate improvement in most cases (e.g. decreased pain,
resolution of abscesses and seromas, and new growth in the
sole and horn wall). The long-term effects of tenotomy can be
extended if the procedure, in addition to therapeutic shoeing,
is performed before evidence of bone disease such as
osteomyelitis or osteoporosis occurs2.
In cases in which tenotomy is performed, it is helpful to work
with a farrier to ensure that proper hoof care is provided.
Proper hoof care entails realignment of the distal phalanx
within the hoof capsule (derotation), and postoperative
support of the heel area.
Derotation can be performed before or at the time of surgery
using radiographs or the plane of the frog to determine the
amount of heel to be removed. In lowering the heels, the
distal phalanx should be repositioned as parallel to the
ground as possible, thus taking the weight off the anterior
portion of the bone. Lowering the heel in a tapered fashion
begins at the apex of the frog and continues in a posterior
direction until the frog is nearly parallel to the ground.
Trimming in this manner increases the amount of hoof surface
at the heels in contact with the ground before tenotomy, thus
creating further stability following surgery. The toe is
shortened from the dorsal hoof wall back to the white line (zona
alba) to further align the hoof capsule to the dorsal surface
of the distal phalanx and remove any additional bending forces
at the toe. If hoof trimming is performed before surgery, the
horse should be placed in wedges until surgery is performed
because the force exerted by the deep digital flexor tendon on
the newly trimmed hoof will increase the horse's discomfort.
Tenotomy is performed on the standing animal using a proximal
metacarpal palmar nerve block. A 2 to 3 cm incision is made
over the lateral aspect of the deep digital flexor tendon in
the middle of the third metacarpal bone. This approach
provides good exposure of the tendon and allows the surgeon to
perform the procedure quickly and safely. The fascia is
separated, and, with the limb flexed, the tendon is isolated
and brought to the surface of the wound using small, curved
retractors. The tendon is transected (Figure 1), and the wound
is closed using a few skin staples. The limb is then bandaged.
The bandage is changed at weekly intervals. The use of an
extended heel shoe or preferably an egg bar shoe is indicated
following surgery. This shoe will prevent the toe lift that
may accompany a deep digital flexor tenotomy and will support
the posterior aspect of the foot as the horse's weight shifts
toward the heels. Shoeing will also prevent stretching of the
palmar joint capsule, which results when the distal phalanx is
returned to a more normal angle. This is thought to cause pain
in the caudal hoof area.
Recently this author has glued most of the shoes on horses
with laminitis. The advantages are it causes no trauma to the
foot and the amount of composite used on the ground surface
can be varied to provide better alignment of the bone within
the hoof and eliminate sole pressure
If laminitic abscessation has occurred and is draining in the
sole, a treatment plate made from ¼ in aluminum or aviation
grade plastic can be attached to toe bottom of the shoe to
facilitate treatment of the solar area. This plate can hold
medication (such as gauze soaked in povidone iodine) against
the solar area and will also protect the sole from bruising.
The shoes can be applied before surgery or two weeks after
surgery when the skin staples or sutures are removed.
Strict stall confinement is a necessity for the patient with
massive laminar damage in which tenotomy was performed early
in the course of the disease. These horses must be confined
until the new growth ring extends three-fourths of the way
down the hoof wall (this requires about six months). This
amount of growth is necessary to establish a sufficient bond
between the hoof wall and distal phalanx to adequately support
the weight of the horse. Premature turnout or hand walking
invariably results in treatment failure.
The chronic laminitis patient is confined to the stall for one
month following a tenotomy, and brief periods (10 to 20
minutes twice daily) of hand walking are allowed. Turning the
animal out in a small, flat paddock is permitted during the
second month if the recovery has been satisfactory, as
determined by an increase in hoof growth and sole depth and a
decrease in pulse and lameness. Strict attention to hoof care
and shoeing after surgery is necessary in order to obtain the
maximum long-term benefits from the procedure.
Monthly follow-up radiographs are necessary after tenotomy to
monitor the alignment of the distal phalanx. The distal
phalanx should be realigned with the hoof capsule so that it
is nearly parallel to the ground. Radiographs will help you
determine how much sole should be trimmed to achieve this
realignment. The rapid increase in sole depth after tenotomy
requires that adequate sole be trimmed. Otherwise, extreme
derotation of the distal phalanx may occur with weight
abnormally placed on the heels.
1. Redden, R.F.: International Equine Podiatry Center,
Versailles KY, Personal communication, March 1991.
2. Sullins, K.E.: Standing Musculoskeletal Surgery. Vet. Clin.
North Am. (Eq. Pract.) 7(3):687-688, 1991.