Page 1026 - Adams and Stashak's Lameness in Horses, 7th Edition

992 Chapter 9

and DIP collateral desmitis can be difficult to differenti­ on cases on which corticosteroids have failed. The other
ate using diagnostic analgesia only. Usually navicular advantage is that you can use these products around
VetBooks.ir and suspensory ligament of the navicular bone) will usu­ and Noltrex™) have become available as a new intra
shows without the worry about possible testing.
bone and associated ligament injuries (impar ligament
In recent years, polyacrylamide gels (Arthramid™
ally block out not only to a PD nerve block but also to a
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DIP joint block and a navicular bursa block. Horses articular injection. The gel acts initially as a joint lubri­
with DDFT lesions will block only partially to a PD cant and then gets integrated in the synovium improving
nerve block and to a DFTS block if located in the distal its elasticity. Clinical results on OA cases have been
tendon sheath and will block well to a PD nerve block impressive even in cases that were refractory to other
and to the navicular bursa block or a DIP joint block if modalities.
located within the navicular bursa and to a PD block When this initial management fails or fails to last
and DIP joint block if the lesion is located at the level of long enough, cross‐sectional imaging such as MRI or
the insertion. CECT is warranted. MRI and CECT are both very
Horses with DIP joint arthritis/synovitis will usually valuable imaging modalities for injuries of the foot. In
display effusion of the DIP joint and block well to a PD the author’s experience both MRI on horses anesthe­
nerve block and to a DIP joint block. DIP collateral tized and CECT are equally sensitive for most soft tis­
desmitis rarely displays palpable asymmetry, tends to sue lesions and structural bony lesions. MRI on horses
block only partially to the PD block and a DIP joint standing has been (in the authors’ experience) less sen­
block, and often requires a pastern ring block or a basis­ sitive and more susceptible to motion artifact. MRI
esamoid nerve block to resolve totally. presents the advantage over CECT to detect physio­
Navicular bone injuries such as subchondral bone logic bony lesions (bone bruising or bone edema) on
cysts, fragmentation of the distal border, increased size STIR. CECT offers the major advantages over MRI to
of vascular channels, and enthesiopathy of the attach­ be much faster and more importantly to allow CT
ment of the suspensory ligament of the navicular bone guidance of needles to perform intralesional therapeu­
are common and can be diagnosed easily using radiog­ tic injections.
raphy. Early and/or less obvious lesions without a radio­ Once a definitive diagnosis is made, the most appro­
graphic representation could be detected using nuclear priate treatment is indicated. This can consist in treat­
scintigraphy or cross‐sectional imaging such as CT or ment of bone injuries (such as navicular bone edema or
MRI. Bone bruising or edema is best seen on MRI STIR bruising or pedal osteitis) using rest, anti‐inflammato­
sequences. ries, and potentially bisphosphonates (tiludronate, clo­
Abnormalities of the impar ligament and distal aspect dronate, zoledronate). Collateral ligaments and DDFT
of the DDFT could be identified using transcuneal ultra­ lesions can be further treated using extracorporeal
sonography, although image quality is not always ideal, shockwave therapy (ESWT) high‐intensity lasers or
and there is a chance to miss subtle lesions as well as intralesional injections. Intralesional injections are per­
other lesions within the foot. formed under ultrasound guidance if the lesions can be
Effusion within the navicular bursa and some lesions seen or when available under CT guidance. The reader is
of the DDFT proximal to the navicular bone can be seen referred to Chapter 8 for further information on these
with ultrasonography between the heel bulbs. This is therapeutic options.
enhanced when a microconvex probe is used because of
the smaller footprint, which allows for a better contact. Lower Hock OA
Injuries of the suspensory ligament of the navicular bone
are harder to evaluate using ultrasonography. Lower hock joint OA is also extremely common in
Only 50% of the injuries to the collateral ligament of sport horses. Most common complaints include lame­
the coffin joints can be seen using ultrasonography. A ness but more often the lack of engagement, loss of
small percentage has typical radiographic changes with stride length, and poor impulsion. Complaints about
osteolysis at the site of insertion onto the third phalanx. jumpers and eventers will often include loss of scope
Initial management usually entails rest and corrective jumping and the inability to stay centered while jump­
shoeing, trying to adjust the hoof pastern angles and lat­ ing. Dressage riders will complain about the inability to
eral medial unbalance. Bar shoes or onion shoes are perform advanced figures necessitating significant col­
often used as they support the heels and help decrease lection such as piaffe or passage. Lameness is usually
the sinking of the heels during the caudal phase of the bilateral. Positive spavin flexion test is usually part of
stance on soft ground, theoretically diminishing pres­ the findings. Radiographs can show various degrees of
sure on the navicular apparatus and coffin joint. For bone spurring, sclerosis, and joint space thinning with
suspect collateral desmitis, asymmetric shoes with a little correlation to the degree of lameness. In most cases
wider bar on the side of the injury are often used. Pads intra‐articular blocks of the tarsometatarsal (TMT) and
or fillers are often used as well. Onion shoes with a plate distal intertarsal (DIT) joints improve significantly the
open over the frog are becoming increasingly popular. lameness. In some cases, a tibial and peroneal nerve
DIP joint injection and navicular bursa injections block is necessary to see an improvement. Most often,
with corticosteroids and hyaluronic acid or glycosami­ these joints are medicated with corticosteroids and hya­
noglycans are often part of the initial treatment. luronic acid or glycosaminoglycan as a therapeutic trial
Alternatively, the use of biologics such as interleukin‐1 without blocking. Using a shoe with a small lateral plan­
13
receptor antagonist protein (IRAP), platelet‐rich tar extension is thought to normalize the landing pat­
plasma, or protein solutions (Pro‐Stride ) is becoming tern of the foot and is often used in conjunction with
TM 3
increasingly popular, as it seems to deliver clinical results joint injections.