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.
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.
OBJECTIVE To describe clinical use of a locking compression plate (LCP) for proximal interphalangeal joint (PIPJ) arthrodesis in horses and compare outcomes for horses that underwent the procedure as treatment for fracture of the middle phalanx (P2) versus other causes.
DESIGN Retrospective case series.
ANIMALS 29 client-owned horses.
PROCEDURES Medical records of 2 veterinary teaching hospitals from 2008 through 2014 were reviewed to identify horses that underwent PIPJ arthrodesis of 1 limb. Signalment, surgical, and outcome-related variables were recorded. Owners were contacted from 1 to 6 years after surgery to determine rehabilitation time, current use of the horse, and overall owner satisfaction with the procedure. Success was determined on the basis of owner satisfaction and outcome for intended use. Variables of interest were compared statistically between horses that underwent surgery for P2 fracture versus other reasons.
RESULTS 14 horses underwent surgery for treatment of P2 fracture, and 15 had surgery because of osteoarthritis, subluxation, or osteochondrosis. Median convalescent time after surgery (with no riding or unrestricted exercise) was 7 months. Four horses were euthanized; of 23 known alive at follow-up, 22 were not lame, and 18 had returned to their intended use (8 and 10 at higher and lower owner-reported levels of work, respectively). Horses undergoing arthrodesis for reasons other than fracture were significantly more likely to return to their previous level of work. Twenty-two of 24 owners contacted indicated satisfaction with the procedure.
CONCLUSIONS AND CLINICAL RELEVANCE Surgical arthrodesis of the PIPJ was successful in most horses of the study population. Various nuances of the system for fracture repair need to be understood prior to its use.
Objective—To determine outcome associated with cutaneous tumors treated via intratumoral chemotherapy with cisplatin and identify risk factors affecting local tumor control and complications in equidae.
Design—Retrospective case series.
Animals—573 equidae with 630 cutaneous tumors.
Procedures—Medical records of horses, mules, donkeys, and ponies with cutaneous tumors treated via intratumoral chemotherapy with cisplatin were analyzed.
Results—549 horses, 13 mules, 8 donkeys, and 3 ponies with 630 histologically confirmed cutaneous tumors were included. Tumors included sarcoids (n = 409), squamous cell carci nomas (151), soft tissue sarcomas (28), cutaneous lymphomas (26), and melanomas (16). Overall cure rate, defined as local control at 4 years, was 93.3%. For all tumor stages combined, cure rates after 1 course of treatment were 96.3% for sarcoids, 96% for lym-phomas, 88% for squamous cell carcinomas, 85% for soft tissue sarcomas, and 81% for melanomas. Treatment protocol, tumor stage, and prior treatment were significant prog nostic factors for tumor control. Treatment efficacy was lower for large tumors, those with gross postoperative residual disease, and those that had been treated previously with other modalities. Treatment was well tolerated. Local reactions were more likely to occur and to be more severe after the third and fourth treatment sessions.
Conclusions and Clinical Relevance—Results confirmed the value of intratumoral chemotherapy with cisplatin for treatment of cutaneous tumors in equidae.The results cannot be extrapolated to other formulations of cisplatin or other protocols that might be used.
Objective—To optimize the isolation and culture of mesenchymal stem cells (MSCs) from umbilical-cord blood (UCB), identify variables that predicted successful MSC isolation, and determine whether shipping, processing, and cryopreservation altered MSC viability, recovery rates, and expansion kinetics.
Sample Population—UCB samples from 79 Thoroughbred and Quarter Horse mares.
Procedures—UCB samples were processed to reduce volume and remove RBCs. Nucleated cells (NCs) were cryopreserved or grown in various culture conditions to optimize MSC monolayer expansion and proliferation. Donor and UCB-sample factors were analyzed to determine their influence on the success of MSC isolation and monolayer expansion.
Results—MSCs capable of multilineage in vitro differentiation were expanded from > 80% of UCB samples. Automated UCB processing and temperature-controlled shipping facilitated sterile and standardized RBC reduction and NC enrichment from UCB samples. The number of NCs after UCB samples were processed was the sole variable that predicted successful MSC expansion. The UCB-derived MSCs and NCs were successfully cryopreserved and thawed with no decrease in cell recovery, viability, or MSC proliferation. The use of fibronectin-coated culture plates and reduction of incubator oxygen tension from 20% to 5% improved the MSC isolation rate. Some UCB-derived MSC clones proliferated for > 20 passages before senescence. Onset of senescence was associated with specific immunocytochemical changes.
Conclusions and Clinical Relevance—Equine UCB samples appeared to be a rich source of readily obtainable, highly proliferative MSCs that could be banked for therapeutic use.
Objective—To describe clinical and scintigraphic abnormalities in horses with a bone fragility disorder.
Design—Retrospective case series.
Animals—16 horses with scintigraphic evidence of multiple sites of increased radiopharmaceutical uptake (IRU).
Procedures—Medical records were reviewed for information on signalment; history; clinical, clinicopathologic, and diagnostic imaging findings; and treatment. Follow-up information was obtained through telephone interviews with owners.
Results—Horses ranged from 4 to 22 years old; there were 8 castrated males and 8 females. Foci of IRU most commonly involved the scapulae, ribs, sternebrae, sacral tubers, ilia, and cervical vertebrae. Most horses were examined because of chronic intermittent (n = 10) or acute (6) lameness involving a single (10) or multiple (6) limbs that could not be localized by means of regional anesthesia. Cervical stiffness (n = 3), scapular bowing (3), swayback (3), and ataxia (1) were also seen in more advanced cases. Signs of respiratory tract disease and exercise intolerance were evident in 4 horses. Ultrasonographic or radiographic evidence of bone remodeling or degeneration was seen in 19 of 33 affected bones. Histologic examination of bone biopsy specimens revealed reactive bone. Improvement was initially seen with conservative treatment in some horses, but the condition worsened in all horses, and 11 horses were euthanized within 7 years.
Conclusions and Clinical Relevance—Results suggested that horses may develop a bone fragility disorder characterized clinically by an unlocalizable lameness and scintigraphically by multiple sites of IRU involving the axial skeleton and proximal portion of the appendicular skeleton.
Objective—To assess clinical outcomes and scintigraphic findings in horses with a bone fragility disorder (BFD) treated with zoledronate (a nitrogen-containing bisphosphonate).
Design—Prospective uncontrolled clinical trial.
Animals—10 horses with evidence of a BFD.
Procedures—Signalment, history, and geographic location of horses' home environments were recorded. Physical examinations, lameness evaluations, and nuclear scintigraphy were performed. Diagnosis of a BFD was made on the basis of results of clinical and scintigraphic examination. Each horse was treated with zoledronate (0.075 mg/kg [0.034 mg/lb, IV, once]) at the time of diagnosis. Horses were reevaluated 6 months after treatment.
Results—Affected horses were from the central and coastal regions of California and had ≥ 1 clinical sign of the disorder; these included scapular deformation (n = 2), lordosis (1), nonspecific signs of musculoskeletal pain (1), and lameness that could not be localized to a specific anatomic region (9). All horses had multiple sites of increased radiopharmaceutica uptake during initial scintigraphic evaluation of the axial skeleton and bones of 1 or both forelimbs. Six months after treatment, clinical improvement (defined as improvement in the lameness score, resolution of signs of musculoskeletal pain, or both) was detected in 9 of 10 horses; scintigraphic uptake was unchanged (n = 2) or subjectively decreased (8). No adverse effects attributed to zoledronate treatment were detected.
Conclusions and Clinical Relevance—Treatment with zoledronate appeared to be useful in improving clinical outcome and scintigraphic findings in horses with a BFD; however, future placebo-controlled studies are necessary to accurately determine efficacy and long-term safety.