Objective—To determine whether iatrogenic
hemarthrosis of the metacarpophalangeal joint could
be used as a model for temporary reversible joint pain
Animals—8 adult horses.
Procedure—Each horse was evaluated on a treadmill
before and after injection of 1 metacarpophalangeal
joint with 10 mL of autogenous blood. Horses were
evaluated subjectively and objectively by use of a
computerized force measurement system at intervals
until lameness abated. The mean force difference
between injected and noninjected limbs at all time
periods after injection was compared with the difference
between limbs at baseline. From each horse,
synovial fluid samples collected before and 24 hours
and 30 days after injection were analyzed for total protein
concentration and cell type and number. Venous
blood samples were collected before and 6 and 24
hours after injection for assessment of plasma cortisol
Results—For 24 hours after injection, the mean force
difference between injected and noninjected limbs
was significantly increased over baseline. The greatest
force difference was detected after 2 and 4 hours.
Baseline and 24-hour force data were not significantly
different. Compared with baseline values, synovial
fluid protein concentration and nucleated cell and
RBC counts were increased significantly at 24 hours
after injection but were not different at 30 days after
injection. No significant changes in plasma cortisol
concentration were detected at any time point.
Conclusions and Clinical Relevance—In horses,
iatrogenic hemarthrosis of the metacarpophalangeal
joint appears to induce temporary reversible lameness
with a mild to moderate degree of synovitis.
(Am J Vet Res 2005;66:1084–1089)
OBJECTIVE To describe the use of CT in the diagnosis of and presurgical planning for equids with keratomas treated by hoof wall resection and determine postoperative complications and outcome.
DESIGN Retrospective case series.
ANIMALS 29 horses and 3 mules with keratomas treated by partial or complete hoof wall resection following CT imaging of the distal portion of the affected extremity from 2005 through 2016.
PROCEDURES For each equid, physical examination and lameness evaluation were performed, followed by imaging of the distal portion of the affected extremity. A tentative diagnosis of keratoma was made given results of clinical, radiographic, and CT examination, with the definitive diagnosis made on histologic examination. After CT imaging, each equid was treated with hoof wall resection.
RESULTS CT allowed accurate identification of the size and location of 35 keratomas in 33 feet. Thirty equids underwent partial and 2 underwent complete hoof wall resection for keratoma removal. Complications developed in 4 of 31 (13%) equids and included excessive granulation tissue formation at the surgical site (n = 1), excessive granulation tissue formation and worsening lameness (1), incomplete keratoma removal with suspected regrowth (1), and incomplete healing of the surgical site with distal interphalangeal joint sepsis secondary to repeated debridement of abnormal tissue (1). Twenty-eight of 31 (90%) equids returned to their previous activity level.
CONCLUSIONS AND CLINICAL RELEVANCE Preoperative CT examination of the feet was useful in the diagnosis of and surgical planning for keratomas in equids. A low complication rate was achieved with the described techniques.
OBJECTIVE To evaluate the use of a laparoscopic specimen retrieval pouch for removal of intact or fragmented cystic calculi from standing horses.
DESIGN Retrospective case series.
ANIMALS 8 horses (5 geldings and 3 mares) with cystic calculi.
PROCEDURES Physical examination and cystoscopic, ultrasonographic, and hematologic evaluations of urinary tract function were performed for each horse. A diagnosis of cystic calculus was made on the basis of results of cystoscopy and ultrasonography. Concurrent urolithiasis or other urinary tract abnormalities identified during preoperative evaluation were recorded. Horses were sedated and placed in standing stocks, and the perineum was aseptically prepared. Direct access to the urinary bladder was gained in geldings via perineal urethrotomy or in mares by a transurethral approach. Calculi were visualized endoscopically, manipulated into the retrieval pouch, and removed intact or fragmented (for larger calculi).
RESULTS For 4 geldings and 1 mare, fragmentation was necessary to facilitate calculus removal. Mean duration of surgery was 125 minutes, and trauma to the urinary bladder and urethra was limited to areas of hyperemia and submucosal petechiation. No postoperative complications were encountered for any horse. When lithotripsy was required, the retrieval pouch provided an effective means of stabilizing calculi and containing the fragments for removal.
CONCLUSIONS AND CLINICAL RELEVANCE Use of the laparoscopic specimen retrieval pouch was an effective, minimally traumatic method for retrieving cystic calculi from standing horses. The pouch protected the urinary bladder and urethra from trauma during calculus removal and allowed for stabilization, containment, and fragmentation of calculi when necessary.
Objective—To compare variables for screw insertion, pushout strength, and failure modes for a headless tapered compression screw inserted in standard and oversize holes in a simulated lateral condylar fracture model.
Sample Population—6 pairs of third metacarpal bones from horse cadavers.
Procedure—Simulated lateral condylar fractures were created, reduced, and stabilized with a headless tapered compression screw by use of a standard or oversize hole. Torque, work, and time for drilling, tapping, and screw insertion were measured during site preparation and screw implantation. Axial load and displacement were measured during screw pushout. Effects of drill hole size on variables for screw insertion and screw pushout were assessed by use of Wilcoxon tests.
Results—Drill time was 59% greater for oversize holes than for standard holes. Variables for tapping (mean maximum torque, total work, positive work, and time) were 42%, 70%, 73%, and 58% less, respectively, for oversize holes, compared with standard holes. Variables for screw pushout testing (mean yield load, failure load, failure displacement, and failure energy) were 40%, 40%, 47%, and 71% less, respectively, for oversize holes, compared with standard holes. Screws could not be completely inserted in 1 standard and 2 oversize holes.
Conclusions and Clinical Relevance—Enlarging the diameter of the drill hole facilitated tapping but decreased overall holding strength of screws. Therefore, holes with a standard diameter are recommended for implantation of variable pitch screws whenever possible. During implantation, care should be taken to ensure that screw threads follow tapped bone threads.
To determine the median time to maximum concentration (tmax) of amikacin in the synovial fluid of the tarsocrural joint following IV regional limb perfusion (IVRLP) of the drug in a saphenous vein of horses.
7 healthy adult horses.
With each horse sedated and restrained in a standing position, a 10-cm-wide Esmarch tourniquet was applied to a randomly selected hind limb 10 cm proximal to the point of the tarsus. Amikacin sulfate (2 g diluted with saline [0.9% NaCl] solution to a volume of 60 mL) was instilled in the saphenous vein over 3 minutes with a peristaltic pump. Tarsocrural synovial fluid samples were collected at 5, 10, 15, 20, 25, and 30 minutes after completion of IVRLP. The tourniquet was removed after collection of the last sample. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median maximum amikacin concentration and tmax were determined.
1 horse was excluded from analysis because an insufficient volume of synovial fluid for evaluation was obtained at multiple times. The median maximum synovial fluid amikacin concentration was 450.5 μg/mL (range, 304.7 to 930.7 μg/mL), and median tmax was 25 minutes (range, 20 to 30 minutes). All horses had synovial fluid amikacin concentrations ≥ 160 μg/mL (therapeutic concentration for common equine pathogens) at 20 minutes after IVRLP.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that, in healthy horses, maintaining the tourniquet for 20 minutes after IVRLP of amikacin in a saphenous vein was sufficient to achieve therapeutic concentrations of amikacin in the tarsocrural joint.
Objective—To develop an objective, accurate method
for quantifying forelimb ground reaction forces in
horses by adapting a human in-shoe pressure measurement
system and determine the reliability of the
system for shod and unshod horses.
Animals—6 adult Thoroughbreds.
Procedure—Horses were instrumented with a
human in-shoe pressure measurement system and
evaluated at a trot (3 m/s) on a motorized treadmill.
Maximum force, stance time, and peak contact area
were evaluated for shod and unshod horses. Three
trials were performed for shod and unshod horses,
and differences in the measured values were examined
with a mixed model ANOVA for repeated measures.
Sensor accuracy was evaluated by correlating
measured variables to clinically observed lameness
and by a variance component analysis.
Results—4 of 6 horses were determined to be lame
in a forelimb on the basis of clinical examination and
measured values from the system. No significant differences
were observed between shod and unshod
horses for maximum force and stance time. A significant
decrease in peak contact area was observed for
shod and unshod horses at each successive trial.
Maximum force measurements provided the highest
correlation for detecting lameness ( r = 0.91, shod
horses; r = 1.0, unshod horses). A variance component
analysis revealed that 3 trials provided a variance
of 35.35 kg for maximum force (± 5.78% accuracy),
0.007 seconds for stance time (± 2.5% accuracy), and
8.58 cm2 for peak contact area (± 11.95% accuracy).
Conclusions and Clinical Relevance—The in-shoe
pressure measurement system provides an accurate,
objective, and effective method to evaluate lameness
in horses. ( Am J Vet Res 2001;62:23–28)
Objective—To test the hypothesis that postanesthetic sedation with romifidine would dose-dependently improve recovery quality of recovery from isoflurane anesthesia in horses more than postanesthetic sedation with xylazine.
Animals—101 healthy adult horses examined at the University of California-Davis Veterinary Medical Teaching Hospital from 2007 to 2009.
Procedures—Horses were sedated with xylazine, and anesthesia was induced with guaifenesin, diazepam, and ketamine via a standardized drug protocol. Anesthesia for surgical or diagnostic procedures was maintained with isoflurane in oxygen for 1 to 4 hours. At the end of anesthesia, horses were moved to a padded stall for recovery. Once the breathing circuit was disconnected and the patient was spontaneously breathing, either xylazine (100 or 200 μg/kg [45 or 91 μg/lb]) or romifidine (10 or 20 μg/kg [4.5 or 9.1 μg/lb]) was administered IV. Objective patient, surgical, and anesthesia data were recorded. Subjective visual analog scale (VAS) scores of recovery quality were assigned by a single individual who was unaware of the treatment received. A stepwise linear regression model was used to correlate patient and procedure factors with the VAS score.
Results—Painful procedures, longer anesthesia times, and the Arabian horse breed were associated with poorer VAS scores. Adjustment for these factors revealed an improved VAS recovery score associated with the use of a romifidine dose of 20 μg/kg.
Conclusions and Clinical Relevance—In healthy adult horses anesthetized with isoflurane for > 1 hour, the results of this study supported the use of 20 μg of romifidine/kg, IV, rather than lower romifidine doses or xylazine, for postanesthetic sedation to improve recovery quality.
Objective—To define the reference range for laminar blood flow (BF) and vascular permeability (VPM) in horses without laminitis by use of dynamic contrast-enhanced computed tomography (CT).
Animals—9 adult horses that were not lame and had no abnormalities of the laminae or phalanges detectable via radiographic examination.
Procedures—Each horse was anesthetized by use of a routine protocol. Horses were placed in right or left lateral recumbency with the dependent forelimb in the CT gantry; only 1 limb of each horse was scanned. Serial 10-mm collimated transverse CT images were acquired at the same location every other second for 90 seconds during infusion of ionic, iodinated contrast medium. Custom software was used to estimate BF, VPM, and fractional vascular volume (FVV) in the dorsal, dorsomedial, and dorsolateral laminar regions.
Results—Among the 9 horses' forelimbs, mean ± SD dorsal laminar BF was 0.43 ± 0.21 mL•min−1•mL−1. Mean dorsomedial and dorsolateral laminar BFs were 0.26 ± 0.16 mL•min−1•mL−1 and 0.24 ± 0.16 mL•min−1•mL−1, respectively. Mean dorsal laminar VPM was 0.09 ± 0.03 mL•min−1•mL−1. Mean dorsomedial and dorsolateral laminar VPMs were 0.16 ± 0.06 mL•min−1•mL−1 and 0.12 ± 0.06 mL•min−1•mL−1, respectively. Mean dorsal laminar FVV was 0.63 ± 0.20 and dorsomedial and dorsolateral laminar FVV were 0.37 ± 0.14 and 0.34 ± 0.17, respectively.
Conclusions and Clinical Relevance—In horses, laminar BF, VPM, and FVV can be non-invasively measured by use of dynamic contrast-enhanced CT.
Case Description—3 horses with penetrating wounds to the shoulder area were examined because of forelimb lameness.
Clinical Findings—All horses had physical examination findings (decreased cranial phase of the stride, swelling in the shoulder region, and signs of pain on manipulation of the shoulder) that were suggestive of problems in the upper portion of the forelimb. Injury to the biceps tendon or bursa was the primary differential diagnosis in each instance, but no abnormalities involving those structures were found. Radiographic and ultrasonographic imaging revealed injuries to the caudal eminence of the greater tubercle of the humerus, the infraspinatus tendon, and the infraspinatus bursa. Examination with ultrasound was more sensitive than radiography at detecting both osseous and soft tissue changes.
Treatment and Outcome—All 3 horses responded favorably to treatment with antimicrobials and non-steroidal anti-inflammatory drugs. Although initial response to standing lavage was favorable in 1 horse, endoscopic lavage was later required. Standing removal of fracture fragments was performed in 2 horses. Ultrasonographic imaging was helpful in monitoring the response to treatment and changes in the affected structures. All 3 horses eventually became sound after treatment.
Clinical Relevance—Infraspinatus bursitis and tendonitis should be included in the differential diagnoses of horses with shoulder lameness. Diagnosis and monitoring should include ultrasonographic monitoring. The prognosis for return to soundness after appropriate treatment appears to be good.
Objective—To evaluate use of a diode laser to induce tendinopathy in the superficial digital flexor tendon (SDFT) of horses.
Animals—4 equine cadavers and 5 adult horses.
Procedures—Cadaveric SDFT samples were exposed to a diode laser at various energy settings to determine an appropriate energy for use in in vivo experiments; lesion size was assessed histologically. In vivo experiments involved laser energy induction of lesions in the SDFT (2 preliminary horses [0, 25, 75, and 87.5 J] and 3 study horses [0 and 125 J]) and assessment of lesions. Study duration was 21 days, and lesions were assessed clinically and via ultrasonography, MRI, and histologic evaluation.
Results—Lesion induction in cadaveric tissues resulted in a spherical cavitated core with surrounding tissue coagulation. Lesion size had a linear relationship (R2 = 0.9) with the energy administered. Size of in vivo lesions in preliminary horses indicated that larger lesions were required. In study horses, lesions induced with 125 J were ultrasonographically and histologically larger than were control lesions. At proximal and distal locations, pooled (preliminary and study horses) ultrasonographically assessed lesions were discrete and variable in size (mean ± SEM lesion percentage for control lesions, 8.5 ± 3%; for laser lesions, 12.2 ± 1.7%). Ultrasonography and MRI measurements were associated (R2 > 0.84) with cross-sectional area measurements.
Conclusions and Clinical Relevance—In vivo diode laser–induced lesions did not reflect cadaveric lesions in repeatable size. Further research is required before diode lasers can reliably be used for inducing tendinopathy.