Page 493 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 459

joint. 36,45,56 Ultrasound can be performed either between benefit over conservative treatment has been ques-
106
the heel bulbs or through the frog after it has been sof- tioned. Other surgical options in horses with DDFT
VetBooks.ir be difficult depending on its location and the skill of the ment to reduce the strain on the DDFT during healing
injuries include desmotomy of the inferior check liga-
tened by soaking. However, documenting the lesion may
operator. Certain aspects of both the DDFT and
and PD neurectomy if other therapies have failed to
podotrochlear apparatus are inaccessible with ultra- improve the lameness. 106
sound, suggesting that negative findings do not rule out Intralesional treatment of DDFT lesions with biolog-
56
the presence of a lesion. Because of these limitations, ics at other locations may be performed with CT, MRI,
ultrasound is currently being used to aid in the treat- or ultrasound guidance but may require the horse to be
ment of specific lesions within the DDFT that have been anesthetized. 3,90,91 A technique to inject the insertion of
identified with other imaging modalities. Similar to the DDFT at the level of P3 using radiographic guidance
1
MRI, contrast‐enhanced CT can also be used to docu- has also been described. Intrabursal or intrasynovial
ment abnormalities in the DDFT within the hoof capsule injection of medications (biologics or anti‐inflammato-
but can only be performed under general anesthesia. 89–92,131 ries) without navicular bursoscopy can also be per-
See Chapter 3 for further information on the use of formed. Corticosteroids alone or combined with HA
diagnostic imaging modalities within the foot. may be used to reduce the inflammation and pain, or
biological compounds such as stem cells or platelet‐rich
Treatment plasma may be used to hopefully promote tendon heal-
ing. Regional IV perfusion of stem cells has also been
The most important aspects of treatment of soft tissue used in select horses with DDFT injuries, but the efficacy
injuries of the foot are rest, rehabilitation, and corrective of this treatment is unknown. See Chapter 8 for more
foot care. 57,104–106 Foot imbalances that may have contrib- detailed information on these treatment modalities.
uted to their occurrence such as low heels, long toes,
mediolateral imbalance, reverse angle of the distal pha- Prognosis
lanx, etc. should be corrected if possible. Horses with
injuries to the podotrochlear apparatus are usually treated In general, horses with primary or secondary DDFT
similarly to horses with navicular disease. Systemic and injuries within the foot have a poor prognosis for return
intrasynovial (DIP joint or navicular bursa) anti‐inflam- to performance. 21,44,57,106 The injury is often a career‐end-
matory therapies are usually performed especially in ing with less than one‐third of affected horses being able
106
horses with combination bone and soft tissue injuries. to return to performance. DDFT injuries are often
Types of shoes that may benefit horses with DDFT negatively associated with prognosis for a variety of rea-
injuries include egg‐bar shoes, reverse shoes, and onion sons and can be difficult and expensive to treat. In one
shoes, all fitted with a rolled toe. The goal of shoeing study of primary DDFT injuries, only 25% of horses
106
is to prevent heel descent during loading in soft ground returned to their previous level of activity within
and promote early break‐over at the toe. Raised heel 18 months. However, the prognosis was dependent on
106
shoes may offer mixed results as they may paradoxically lesion type with dorsal border lesions having a better
exacerbate lameness and may induce contracture of the prognosis than core or parasagittal split lesions. Thirty‐
106
DDFT during tendon healing. Clinically, however, five percent of horses with dorsal border lesions returned
many horses with DDFT lesions initially appear more to their original level of activity. 21,106 Additionally, core
comfortable when placed in elevated heel shoes. lesion size was reported to affect prognosis with lesions
Rest and rehabilitation are usually performed over a with a cross‐sectional area of >20% of the affected lobe
minimum of 6 months and may be necessary for even or a total length of >35 mm corresponding to horses that
longer depending on the lesion severity. The duration of remained lame after treatment. 106,126 Therefore, the over-
rehabilitation is usually dependent on many variables all prognosis of DDFT injuries is often dependent on
including DDFT lesion type, location and size, concurrent lesion size, type, location, and severity and the presence
hoof abnormalities, use of the horse, and wishes of the of concurrent abnormalities within the navicular bone
owner. In general, horses treated with an extended period or other soft tissues (primary vs. secondary). Several
of rest and rehabilitation are thought be able to return to studies have documented that horses with multiple inju-
use for a longer duration than horses without rest. 57,106 ries within the bone and soft tissues of the foot have
Even though rest and rehabilitation are important aspects difficulty returning to performance. 21,36,44,57,106
of treatment, the prognosis with this therapy alone has
not been considered favorable. 36,105,106 Adjunct treatment
approaches for these injuries are discussed below. ACKNOWLEDGMENTS
Additional treatment options for horses with DDFT
lesions often depend on the location of the lesion, but The authors thank Dr. Ted S. Stashak for his contri-
the overall prognosis remains poor. Dorsal border butions to this chapter in the previous edition.
lesions at the level of the navicular bone may benefit
from endoscopy of the navicular bursa and debridement
of any torn tendon fibers. 113,114 Intralesional treatment References
of the DDFT injury and/or treatment of the navicular 1. Anderson JDC, Puchalski SM, Larson RF, et al. Injection of the
bursa with biologics or anti‐inflammatories can be per- insertion of the deep digital flexor tendon in horses using radio-
formed at the time of surgery or subsequent to surgery. graphic guidance. Equine Vet Educ 2008;July:383–388.
Although navicular bursoscopy with tendon debride- 2. Barber MJ, Sampson SN, Schneider RK, et al. Use of magnetic
resonance imaging to diagnose distal sesamoid bone injury in a
ment may be indicated in select cases, its potential horse. J Am Vet Med Assoc 2006;229:717–720.