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SUMMARY

Fifty Thoroughbred horses were examined. All horses had been in race training for a minimum of 4 months before examination and had worked at racing speed; 24 horses had raced. All horses were clinically sound at the time of examination. Ultrasonography was performed, using a 7.5-MHz transducer with built-in fluid offset. Videotaped images of the palmar soft tissue structures were obtained at 4, 8, 12, 16, 20, and 24 cm distal to the base of the accessory carpal bone (dacb). Images were digitized, and each image was calibrated. Values for cross-sectional area (csa) and mean echogenicity (me) were then determined from the cross-sectional images of the superficial digital flexor (sdf) and the deep digital flexor (ddf) tendons, using an image-analysis program.

The sdf tendons were compared between right and left forelimbs at each level, and from proximad to distad on each limb, as were the ddf tendons. The relation between the sdf and ddf tendons for the same forelimb was determined at each level. There were no significant differences in csa or me at equivalent levels of the left and right sdf tendons. Mean (± sd) csa was 1.01 (± 0.12) cm2 at 4 cm dacb, 0.95 (± 0.14) cm2 at 12 cm dacb, and 1.12 (± 0.15) cm2 at 24 cm dacb. Adjusted me was 2.34 (± 0.34) at 4 cm dacb, 2.03 (± 0.38) at 12 cm dacb, and 2.04 (± 0.35) at 24 cm dacb.

The left and right ddf tendons did not have significant differences in csa or me at any level. Cross-sectional area was 1.13 (± 0.18) cm2 at 4 cm dacb, 1.01 (± 0.12) cm2 at 12 cm dacb, and 1.75 (± 0.29) cm2 at 24 cm dacb. Adjusted me was 2.60 (± 0.46) at 4 cm dacb, 2.49 (± 0.49) at 12 cm dacb, and 2.50 (± 0.44) at 24 cm dacb.

At all levels, the left and right sdf tendons were smaller and less echoic than the ddf tendons of the same limb. The sdf and ddf tendons had an hourglass shape, with smallest csa at 12 cm dacb. Mean echogenicity generally decreased for the sdf and ddf tendons from proximad to distad on the limb.

These results indicate that for clinically normal trained Thoroughbred racehorses, there should be no significant difference in csa or echogenicity between the left and right sdf tendons at equivalent distances dacb. There should be no significant differences in the left and right ddf tendons at equivalent levels dacb. The sdf tendon is usually smaller and less echoic than the corresponding ddf tendon at each level.

Free access
in American Journal of Veterinary Research

Summary

Explant cultures were set up, using articular cartilage obtained from metatarsophalangeal joints of 11 horses. Explants from 2 horses were used to determine culture conditions appropriate for tissue viability. The cartilage explants maintained steady-state metabolism of proteoglycans during a 13-day evaluation period. The metabolic response of equine articular cartilage to incubation with recombinant human interleukin 1 (0.01 to 100 ng/ml) was studied, using cartilage obtained from the remaining 9 horses, age of which ranged from 3 months to 20 years. Interleukin 1 induced a dose-dependent release of glycosaminoglycan from the matrix during a 3-day incubation period. It also caused dose-dependent inhibition of glycosaminoglycan synthesis during a 3-hour pulse-labeling period. Expiants obtained from older horses were significantly (P < 0.05) less responsive to interleukin 1, with respect to synthesis and release of glycosaminoglycan.

Free access
in American Journal of Veterinary Research

Summary

Concentrations of amino acids in the plasma of 13 neonatal foals with septicemia were compared with the concentrations of amino acids in the plasma of 13 age-matched neonatal foals without septicemia. Analysis of the results revealed significantly lower concentrations of arginine, citrulline, isoleucine, proline, threonine, and valine in the plasma of foals with septicemia. The ratio of the plasma concentrations of the branched chain amino acids (isoleucine, leucine, and valine) to the aromatic amino acids (phenylalanine and tyrosine), was also significantly lower in the foals with septicemia. In addition, the concentrations of alanine, glycine, and phenylalanine were significantly higher in the plasma of foals with septicemia. Therefore, neonatal foals with septicemia had significant differences in the concentrations of several amino acids in their plasma, compared with concentrations from healthy foals. These differences were compatible with protein calorie inadequacy and may be related to an alteration in the intake, production, use, or clearance of amino acids from the plasma pool in sepsis.

Free access
in American Journal of Veterinary Research

Summary

The concentrations of 23 ammo acids in the plasma of 13 healthy foals were determined before suckling, when foals were 1 to 2 days old, 5 to 7 days old, 12 to 14 days old, and 26 to 28 days old. The ratio of the branched chain amino acids to the aromatic amino acids was also calculated at the 5 time points. Analysis of the concentrations at the 5 ages revealed a significant temporal relationship for each amino acid ranging from a polynomial order of 1 to 4 inclusively. There were significant differences between several concentrations of amino acids in plasma at specific sample times; however, no consistent patterns were revealed. The concentrations of amino acids in healthy foals were markedly different from previously determined values in adult horses. The significant differences in the concentrations of amino acids in plasma of healthy foals at the 5 ages may represent developmental aspects of amino acid metabolism or nutrition.

Free access
in American Journal of Veterinary Research

SUMMARY

Ultrasonographic cross-sectional area (csa) measurements of equine superficial digital flexor (sdf) tendon were obtained to determine the feasibility of ultrasonography for csa measurement of tendon in vivo and in vitro. Ultrasonographic measurements were compared with a more traditional csa measurement method, ink-blot analysis. In addition, values for ultrasonographic sdf tendon mean echogenicity were obtained in vivo and in vitro. The left forelimb sdf tendons of 23 horses were evaluated ultrasonographically. Cross-sectional images were acquired at 4-cm intervals distal to the base of the accessory carpal bone (dacb) to the level of the proximal sesamoid bones while horses were standing squarely. After euthanasia, the left forelimbs were mounted in a materials testing system (mts) and loaded under tension to standing load. Ultrasonographic images were again acquired at the same locations. The ultrasonographic images were digitized, and values for ultrasonographic csa and mean echogenicity were obtained for each level.

Immediately after mechanical testing, a 1-cm-thick transverse section of sdf tendon at 12 cm dacb was removed. Three ink blots were prepared from each end of the removed tendon section and digitized. The 6 csa values were averaged to generate a value for morphologic csa for each sdf tendon at 12 cm dacb.

Standing ultrasonographic tendon csa at 12 cm dacb was consistently smallest (mean ± sd csa = 86 ± 11 mm2), followed by mts ultrasonographic csa (mean, 95 ± 12 mm2), ink-blot morphologic csa being largest (mean, 99 ± 15 mm2). Comparison of standing and mts ultrasonographic csa values at 12 cm dacb revealed a strong positive linear correlation between methods (R2 = 0.74, P = 0.001). Comparison of ink-blot csa at 12 cm dacb with standing and mts ultrasonographic csa revealed strong positive linear correlations (R2 = 0.64, P = 0.001 and R2 = 0.72, P = 0.001, respectively).

For ultrasonographic mean echogenicity, standing values insignificantly exceeded mts values at each level. The authors conclude that ultrasonography is a useful technique for the noninvasive assessment of sdf tendon csa that can be applied in vivo and in vitro.

Free access
in American Journal of Veterinary Research

SUMMARY

Results of studies in human beings and other species have indicated that aging significantly influences the strength, modulus of elasticity, and energy storage ability of tendon. We wanted to determine the effects of aging on the material and ultrasonographic properties of equine superficial digital flexor (sdf) tendon. Ultrasonographic measurements of left forelimb sdf tendon cross-sectional area and mean echogenicity were made in 23 standing horses ranging in age from 2 to 23 years. All horses had not been in work for a minimum of 6 months prior to the study. After euthanasia, left forelimb bone-muscle-tendon-bone specimens were mounted in a materials testing system. The sdf tendon was cyclically loaded sinusoidally 100 times at 0.5 Hz from 1.5 to 5.0% strain, then was submitted to 10-minute creep-and-stress relaxation tests. Modulus of elasticity, load at 3% strain, and creep-and-stress relaxation were determined for each specimen. A significant positive correlation was found between elastic modulus and age. Correlation was not found between age and sdf tendon cross-sectional area or mean echogenicity. When 2-year-old horses were compared with older horses, the latter had tendons with a significantly (P = 0.007) greater modulus of elasticity. The authors conclude that increasing age through maturity is associated with a corresponding increase in equine sdf tendon elastic modulus.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the antinociceptive and sedative effects and duration of action of hydromorphone hydrochloride after IM administration to American kestrels (Falco sparverius).

Animals—11 healthy 2-year-old American kestrels.

Procedures—Hydromorphone (0.1, 0.3, and 0.6 mg/kg) and an equivalent volume of saline (0.9% NaCl) solution (control treatment) were administered IM to kestrels in a masked randomized complete crossover study design. Foot withdrawal response to a thermal stimulus was determined 30 to 60 minutes before (baseline) and 0.5, 1.5, 3, and 6 hours after treatment administration. Agitation-sedation scores were determined 3 to 5 minutes before each thermal test.

Results—Hydromorphone at 0.6 mg/kg, IM, significantly increased the thermal foot withdrawal threshold, compared with the response after administration of saline solution, for up to 3 hours, and hydromorphone at 0.1, 0.3, and 0.6 mg/kg, IM, significantly increased withdrawal responses for up to 6 hours, compared with baseline values. No significant differences in mean sedation-agitation scores were detected between hydromorphone and saline solution treatments; however, appreciable sedation was detected in 4 birds when administered 0.6 mg of hydromorphone/kg.

Conclusions and Clinical Relevance—Hydromorphone at the doses evaluated significantly increased the thermal nociception threshold for American kestrels for 3 to 6 hours. Additional studies with other types of stimulation, formulations, dosages, routes of administration, and testing times are needed to fully evaluate the analgesic and adverse effects of hydromorphone in kestrels and other avian species and the use of hydromorphone in clinical settings.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate antinociceptive effects and pharmacokinetics of butorphanol tartrate after IM administration to American kestrels (Falco sparverius).

Animals—Fifteen 2- to 3-year-old American kestrels (6 males and 9 females).

Procedures—Butorphanol (1, 3, and 6 mg/kg) and saline (0.9% NaCl) solution were administered IM to birds in a crossover experimental design. Agitation-sedation scores and foot withdrawal response to a thermal stimulus were determined 30 to 60 minutes before (baseline) and 0.5, 1.5, 3, and 6 hours after treatment. For the pharmacokinetic analysis, butorphanol (6 mg/kg, IM) was administered in the pectoral muscles of each of 12 birds.

Results—In male kestrels, butorphanol did not significantly increase thermal thresholds for foot withdrawal, compared with results for saline solution administration. However, at 1.5 hours after administration of 6 mg of butorphanol/kg, the thermal threshold was significantly decreased, compared with the baseline value. Foot withdrawal threshold for female kestrels after butorphanol administration did not differ significantly from that after saline solution administration. However, compared with the baseline value, withdrawal threshold was significantly increased for 1 mg/kg at 0.5 and 6 hours, 3 mg/kg at 6 hours, and 6 mg/kg at 3 hours. There were no significant differences in mean sedation-agitation scores, except for males at 1.5 hours after administration of 6 mg/kg.

Conclusion and Clinical Relevance—Butorphanol did not cause thermal antinociception suggestive of analgesia in American kestrels. Sex-dependent responses were identified. Further studies are needed to evaluate the analgesic effects of butorphanol in raptors.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the thermal antinociceptive and sedative effects and duration of action of tramadol hydrochloride after oral administration to American kestrels (Falco sparverius).

Animals—12 healthy 3-year-old American kestrels.

Procedures—Tramadol (5, 15, and 30 mg/kg) and a control suspension were administered orally in a masked randomized crossover experimental design. Foot withdrawal response to a thermal stimulus was determined 1 hour before (baseline) and 0.5, 1.5, 3, 6, and 9 hours after treatment. Agitation-sedation scores were determined 3 to 5 minutes before each thermal stimulus test.

Results—The lowest dose of tramadol evaluated (5 mg/kg) significantly increased the thermal foot withdrawal thresholds for up to 1.5 hours after administration, compared with control treatment values, and for up to 9 hours after administration, compared with baseline values. Tramadol at doses of 15 and 30 mg/kg significantly increased thermal thresholds at 0.5 hours after administration, compared with control treatment values, and up to 3 hours after administration, compared with baseline values. No significant differences in agitation-sedation scores were detected between tramadol and control treatments.

Conclusions and Clinical Relevance—Results indicated oral administration of 5 mg of tramadol/kg significantly increased thermal nociception thresholds for kestrels for 1.5 hours, compared with a control treatment, and 9 hours, compared with baseline values; higher doses resulted in less pronounced antinociceptive effects. Additional studies with other types of stimulation, formulations, dosages, routes of administration, and testing times would be needed to fully evaluate the analgesic and adverse effects of tramadol in kestrels and other avian species.

Full access
in American Journal of Veterinary Research

Objective

To document natural bacterial flora on the ventral aspect of the equine abdomen, to compare 2 preparation techniques, and to identify potential risk factors that may contribute to incisional drainage.

Design

Prospective study.

Animals

53 horses undergoing exploratory celiotomy.

Procedure

Group-1 horses (n = 26) were prepared with povidone-iodine and alcohol. Group-2 horses (27) were prepared with a film-forming iodophor complex. Numbers of bacterial colony-forming units (CFU) were measured before and after surgical scrub, following skin closure, and after recovery from general anesthesia. Swab specimens to identify normal skin bacterial flora and potential pathogens were obtained by swabbing a 4 X 4-cm area. Variables that might affect incisional drainage were also investigated.

Results

For both techniques, there was a significant reduction in bacterial numbers after skin preparation. Incisional drainage was observed in 14 (26%) horses (8 group-1 and 6 group-2 horses). Preexisting dermatitis, poor intraoperative drape adherence, high number of bacterial CFU obtained after recovery from anesthesia, and high number of CFU obtained from the surgery room environment were the main risk factors associated with subsequent incisional drainage. Bacillus spp, nonhemolytic Staphylococcus spp, Micrococcus spp, Corynebacterium spp, Streptomyces spp, other nonenteric genera, and non-hemolytic Streptococcus spp were the most common isolates obtained before surgical scrub.

Conclusions and Clinical Relevance

Both skin preparation techniques were equally effective in reducing numbers of bacterial CFU by 99%, and a significant difference was not found in incisional drainage rate between groups. Protection of the wound during recovery from anesthesia and the immediate postoperative period may reduce incisional drainage after abdominal surgery in horses. (J Am Vet Med Assoc 1999;215:963–969)

Free access
in Journal of the American Veterinary Medical Association