Objective—To determine treatment outcome on the basis of pathological changes identified on MRI and lameness duration in horses with navicular syndrome that underwent injection of corticosteroid and hyaluronan into the navicular bursa.
Design—Retrospective case series.
Animals—101 horses with navicular syndrome.
Procedures—Medical records of horses with signs of navicular syndrome evaluated between January 2000 and December 2008 were reviewed. Data on signalment, use of the horse, history, affected limbs, duration of lameness, findings on lameness examination, radiographic findings, MRI findings, treatment, and outcome were collected from the medical records. Follow-up information was obtained a minimum of 10 months after navicular bursa injection.
Results—Following navicular bursa injection, 76 of 101 (75%) horses returned to their intended use for a mean of 9.66 months, and 35 (35%) were sound at follow-up. Horses that had been lame for < 6 months before treatment were significantly more likely to return to their intended use, have a longer positive response to treatment, and be sound at follow-up, compared with horses that had a longer lameness history. Horses with primary deep digital flexor (DDF) tendonitis responded best to navicular bursa injection with rest and rehabilitation, followed by horses with navicular bursitis and horses with DDF tendonitis and adhesions to the collateral sesamoidean ligament of the distal sesamoid (navicular) bone. Horses with scar tissue in the proximal portion of the navicular bursa, adhesions from the navicular bone to the DDF tendon, or multiple abnormalities did not respond as well to treatment.
Conclusions and Clinical Relevance—Response to navicular bursa injection with corticosteroid and hyaluronan in horses with navicular syndrome was dependent on the disease process detected on MRI and duration of lameness.
Objective—To determine the cardiovascular and respiratory
effects of water immersion in horses recovering
from general anesthesia.
Animals—6 healthy adult horses.
Procedure—Horses were anesthetized 3 times with
halothane and recovered from anesthesia while positioned
in lateral or sternal recumbency in a padded
recovery stall or while immersed in a hydropool.
Cardiovascular and pulmonary functions were monitored
before and during anesthesia and during recovery
until horses were standing. Measurements and
calculated variables included carotid and pulmonary
arterial blood pressures (ABP and PAP, respectively),
cardiac output, heart and respiratory rates, arterial
and mixed venous blood gases, minute ventilation,
end expiratory transpulmonary pressure (PendXes),
maximal change in transpulmonary pressure
(ΔPtpmax), total pulmonary resistance (RL), dynamic
compliance (Cdyn), and work of breathing ().
Results—Immersion in water during recovery from
general anesthesia resulted in values of ABP, PAP, PendXes, ΔPtpmax, RL, and that were significantly greater and values of Cdyn that were significantly less,
compared with values obtained during recovery in a padded stall. Mode of recovery had no significant
effect on any other measured or calculated variable.
Conclusions and Clinical Relevance—Differences in
pulmonary and cardiovascular function between horses
during recovery from anesthesia while immersed
in water and in a padded recovery stall were attributed
to the increased effort needed to overcome the
extrathoracic hydrostatic effects of immersion. The
combined effect of increased extrathoracic pressure
and PAP may contribute to an increased incidence of
pulmonary edema in horses during anesthetic recovery
in a hydropool. (Am J Vet Res 2001;62:1903–1910)
Objective—–To compare transfixation and standard
full-limb casts for prevention of in vitro displacement
of a mid-diaphyseal third metacarpal osteotomy site
Sample Population—6 forelimbs from 6 horses
euthanatized for reasons not related to the musculoskeletal
Procedure—A 30° osteotomy was performed in the
mid-diaphysis of the third metacarpal bone. Two 4.5-mm cortical bone screws were placed across the
osteotomy site to maintain alignment during casting.
Two 6.35-mm Steinmann pins were placed from a lateral-to-medial direction in the distal aspect of the
radius. A full-limb cast that incorporated the pins was
applied. An extensometer was positioned in the
osteotomy site through a window placed in the dorsal
aspect of the cast, and after removal of the screws,
displacement was recorded while the limb was axially
loaded to 5,340 N (1,200 lb). Pins were removed,
and the standard full-limb cast was tested in a similar
Results—The transfixation cast significantly reduced
displacement across the osteotomy site at 445 N (100
lb), 1,112 N (250 lb), 2,224 N (500 lb), and 4,448 N
(1,000 lb), compared with the standard cast.
Conclusion and Clinical Relevance—A full-limb
transfixation cast provides significantly greater resistance
than a standard full-limb cast against axial collapse
of a mid-diaphyseal third metacarpal osteotomy
site when the bone is placed under axial compression.
Placement of full-limb transfixation casts should
be considered for the management of unstable fractures
of the third metacarpal bone in horses. (Am J
Vet Res 2000;61:1633–1635)
Case Description—A 4-year-old Quarter Horse stallion was evaluated because of a 10-month history of moderate (grade 3/5) left forelimb lameness (detectable during trotting over a smooth, hard surface).
Clinical Findings—No abnormalities were detected in either forelimb via palpation or application of hoof testers; however, lameness was eliminated after administration of a palmar digital nerve block in the left forelimb. Whereas radiography and ultrasonography did not identify any left forelimb foot abnormalities, magnetic resonance (MR) imaging revealed a circumscribed soft tissue mass in the distal aspect of the digital flexor tendon sheath (DFTS) dorsal to the lateral aspect of the deep digital flexor tendon. Subsequently, the left forelimb DFTS was injected with local anesthetic, which resulted in 90% improvement of the horse's lameness.
Treatment and Outcome—The distal aspect of the left forelimb DFTS was evaluated tenoscopically. The mass was removed under tenoscopic guidance, after which the distal digital annular ligament was transected. The horse received phenylbutazone orally for 10 days, and the left forelimb DFTS was injected with hyaluronic acid and methylprednisolone acetate 7 days after the surgery. Following a rehabilitation program, the horse was returned to full training at 6 months after surgery and competed successfully during a 2-year follow-up period.
Clinical Relevance—Use of MR imaging should be considered in all lame horses for which a definitive diagnosis cannot be made via radiography, ultrasonography, or other imaging techniques, especially when the lameness has been localized to a specific anatomic region by use of diagnostic anesthesia.
Case Description—A 5-year-old Appaloosa mare was examined for severe left forelimb lameness of 4 months' duration.
Clinical Findings—Lameness was evident at the walk and trot and was exacerbated when the horse circled to the left. Signs of pain were elicited in response to hoof testers placed over the frog of the left front hoof, and a palmar digital nerve block eliminated the lameness. Radiographs revealed no abnormalities, but magnetic resonance imaging (MRI) revealed increased bone density in the medullary cavity of the distal sesamoid (navicular) bone in the proton density and T2-weighted images and a defect in the fibrocartilage and subchondral bone of the flexor cortex.
Treatment and Outcome—Because of the absence of improvement after 4 months and the poor prognosis for return to soundness, the mare was euthanatized. An adhesion between the deep digital flexor tendon and the flexor cortex defect on the navicular bone was grossly evident, and histologic evaluation revealed diffuse replacement of marrow trabecular bone with compact lamellar bone. Changes were consistent with blunt traumatic injury to the navicular bone that resulted in bone proliferation in the medullary cavity.
Clinical Relevance—Use of MRI enabled detection of changes that were not radiographically evident and enabled accurate diagnosis of the cause of lameness. Navicular bone injury may occur without fracture and should be considered as a differential diagnosis in horses with an acute onset of severe unilateral forelimb lameness originating from the heel portion of the foot.
Objective—To determine clinical signs, diagnostic
findings, and outcome for horses with desmitis of the
straight sesamoidean ligament (SSL) near its insertion
on the middle phalanx.
Procedure—Medical records were reviewed, and
information on signalment, history, clinical signs, diagnostic
findings, and treatment was obtained. Followup
information was obtained through telephone conversations
Results—In all horses, the diagnosis was made by
use of high-resolution ultrasonography. Seven horses
had moderate lameness on initial examination; lameness
was exacerbated in 6 horses following flexion of
the distal limb joints. The cause of lameness could
not be determined on the basis of clinical signs, and
diagnostic local anesthesia was necessary to localize
the source of lameness to the distal portion of the
limb. Five horses had forelimb involvement (1 bilateral),
and 4 had hind limb involvement (1 bilateral).
Treatment consisted primarily of a 6-month rest and
rehabilitation program. Six of the 9 horses were able
to return to their intended use.
Conclusions and Clinical Relevance—Results suggest
that injury to the SSL proximal to its insertion on
the middle phalanx should be considered as a possible
cause of lameness in horses, particularly performance
horses, with lameness localized to the distal
portion of the forelimb or hind limb that do not have
any radiographic abnormalities. High-resolution ultrasonography
was necessary to make the diagnosis.
Horses with an acute injury appeared to have a reasonable
chance of responding to treatment and
returning to their intended use. (J Am Vet Med Assoc 2003;222:973–977)
Objective—To describe the location and severity of deep digital flexor tendon (DDFT) lesions diagnosed by means of high-field-strength MRI in horses and to identify variables associated with return to activity following medical treatment.
Design—Retrospective case series.
Procedures—Medical records of horses with DDFT injury diagnosed with MRI over a 10-year period (2000–2010) and treated medically (intrasynovial administration of corticosteroids and sodium hyaluronan, rest and rehabilitation, or both) were reviewed. History, signalment, use, results of lameness examination and diagnostic local anesthesia, MRI findings, and treatment details were recorded. Outcome was obtained by telephone interview or follow-up examination. Horses were grouped by predictor variables and analyzed with logistic regression to identify significant effects.
Results—Overall, of 97 horses available for follow-up (median time to follow-up, 5 years; range, 1 to 12 years), 59 (61%) returned to activity for a mean duration of 22.6 months (median, 18 months; range, 3 to 72 months), with 25 (26%) still sound at follow-up. Of horses with mild, moderate, and severe injury, 21 of 29 (72%), 20 of 36 (56%), and 18 of 32 (56%), respectively, returned to use. Horses treated with intrasynovial corticosteroid injection and 6 months of rest and rehabilitation returned to use for a significantly longer duration than did horses treated without rest. Western performance horses returned to use for a significantly longer duration than did English performance horses.
Conclusions and Clinical Relevance—Results of the present study suggested that outcome for horses with DDFT injuries treated medically depended on injury severity, presence of concurrent injury to other structures in the foot, type of activity, and owner compliance with specific treatment recommendations. Although some horses successfully returned to prior activity, additional treatment options are needed to improve outcome in horses with severe injuries and to improve long-term prognosis.