Page 831 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness Associated with the Axial Skeleton 797

more cranial cervical vertebrae and the ligament. Newer Etiology
MRI equipment (with smaller bore and larger aperture) Osteoarthritis of the cervical facet joints can be the
VetBooks.ir most cases imaging is limited to the level of the fourth or result of osteochondrosis of the articular surfaces, as in
facilitates imaging of the more caudal vertebrae, but in
any other joint affected by osteochondrosis. Trauma to
fifth cervical vertebra.
the neck is often a cause for facet joint arthritis. The
trauma may be the result of trailering accidents, falling
Treatment or hanging in cross ties, running into objects with the
Therapy for desmopathy of the nuchal ligament is neck, falling during exercise (racing, eventing, jumping),
similar to that of any desmopathy: rest and anti‐inflam- flipping backwards, etc. Instability of the neck due to
matory medication, as well as possible extracorporeal malformation of vertebrae or joint surfaces predisposes
shock wave treatment. Biological treatments with stem the horse to facet joint arthritis, and it is often found in
cells, A‐cell, and PRP are in the stage of experimental conjunction with several congenital or developmental
use, and studies to be published in the near future on cervical malformation syndromes.
these therapy modalities will show their effectiveness in
treatment of desmopathies in general and in the nuchal Clinical Signs
ligament in particular.
A specific structure in the poll, the nuchal bursa, Osteoarthritis of the cervical facet joints can cause a
which is present at the dorsal aspect at C1 in nearly all great diversity of symptoms. At first, pain can cause
horses and less frequent at C2, can be involved in pathol- behavior similar to that described for nuchal ligament
ogy of the nuchal ligament. Bursitis is considered to be a pathology.
rare condition. However, many veterinarians in the field When severe bone proliferation is present at or
of sports medicine diagnose bursitis of the nuchal liga- around the facet joints, mobility can be limited, thus
ment quite frequently. It is difficult to completely con- limiting athletic performance. In dressage, the horse may
firm this diagnosis on ultrasonographic examination be reluctant to bend the neck in a lateral direction, bring
alone. CT or MRI imaging, performed under general the head vertical in the collection position, or stretch
anesthesia, can give a more detailed image of the bursa(e) down. A jumper can be difficult when asked for short
and its adjacent structures along with a more confirmed turns or lack balance during the jump due to neck stiff-
diagnosis. A common treatment modality for bursitis of ness, while the barrel racer can be difficult to turn
the nuchal bursa is the ultrasound‐guided injection of around the barrels.
corticosteroids into the bursa. Calcifications in the bursa Due in which several muscles originate at locations in
region are observed quite frequently in the author’s the neck and have their insertion to the scapula (trape-
clinic on routine radiographs of this region; however, in zius muscle, rhomboideus muscle) or humerus (brachio-
these cases the owner of the horse may not always cephalicus muscle), contraction of these muscles can
remember any treatment or problem in this region. cause pain in the arthritic facet joints and thus alter the
gait (e.g., shorter anterior stride, reduced protraction of
the scapula) and mimic shoulder or even lower limb
Prognosis lameness. 15
When given enough time for complete recovery and Neurological symptoms can occur when bone prolif-
rehabilitation, prognosis for nuchal ligament desmopa- eration of the arthritic joint structures protrudes into
thy is favorable. The only exception may be the high‐ the spinal canal, with lower hindquarter activity as the
4
level dressage horses when the initial injury to the most common sign. When the bony proliferation invades
ligament has not been recognized and has developed the intravertebral foramen, root nerves can be com-
11
into a more chronic phase or is considered to be a repeti- pressed. The cervical nerves between C5 and C6, C6
tive stress injury. In these cases, when the horse’s head is and C7, and C7 and T1 (the sixth, seventh, and eighth
in a very high and upright position, as needed for the cervical nerves) form the brachial plexus, so compres-
highest grades of collection, strain to the ligament is the sion of these root nerves can be sensed as pain in the
11,14
highest, and the horse can show pain or defensive behav- limb, and limb lameness may be observed. When
ior such as rearing or shaking the head. root nerve compression is present, a patchy spot of
When calcifications are present due to mineralization sweating may be noticed on one or both sides of the
of a hematoma or corticosteroid deposition, signs of neck and/or thorax.
altered behavior or performance are common, and prog-
nosis is guarded for complete recovery to the initial level Diagnosis
of performance.
At the clinical examination, cervical facet joint arthri-
tis can be suspected when the range of motion in the
CERVICAL FACET JOINTS neck is limited. With complete flexion to the side, the
horse should be able to flex the neck laterally, touching
Osteoarthritis of the cervical facet joints is very com- the thoracic wall with its nose without rotation in C2 in
mon in many horses, even without clinical signs. 4,11 both directions. A 20–30% limitation in the total range
Enlargement of the more caudal facet joints with irregu- of motion in the lateral plane is found in many older
larly shaped or narrowed joint spaces is common on cer- horses without clinical symptoms and can be considered
vical radiographs in horses of any breed at a slightly normal. Cervical facet joint arthritis is highly suspected
older age (older than 4–5 years) (Figure 6.41). with an asymmetric limitation of the range of motion.