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Objective—To develop and validate a novel instrumented treadmill capable of determining vertical ground reaction forces of all 4 limbs simultaneously in horses.

Sample Population—Data obtained while a horse was walking and trotting on the treadmill.

Procedure—18 piezo-electric force transducers were mounted between the treadmill frame and supporting steel platform to measure the actual forces at the corresponding bearing points. Each of the 18 sensor forces is equal to the sum of the unknown hoof forces weighted with the transfer coefficients of the corresponding force application points. The 4 force traces were calculated, solving at each time point the resulting equation system, using the Gaussian least-squares method. System validation comprised the following tests: determination of the survey accuracy of the positioning system, determination of the natural frequencies of the system, linearity test of the force transfer to the individual sensors, determination of superimposed forces with the treadmill-integrated force measuring system (TiF) in a static configuration, and comparison of vertical ground reaction forces determined simultaneously by use of TiF and force shoes mounted on the forelimbs of a horse.

Results—Comparison between static test loads and TiF-calculated forces revealed deviations of < 1.4%. Force traces of TiF-calculated values and those recorded by use of the force shoes were highly correlated ( r ≥ 0.998).

Conclusions and Clinical Relevance—This instrumented treadmill allows a reliable assessment of load distribution and interlimb coordination in a short period and, therefore, is suitable for use in experimental and clinical investigations. (Am J Vet Res 002;63:520–527).

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in American Journal of Veterinary Research


Objective—To evaluate a modified posterior rhinomanometric method for clinical application in dogs.

Animals—15 healthy Beagles and 8 Bulldogs (4 healthy and 4 with respiratory problems).

Procedures—Rhinomanometry was performed 3 times within a 15-minute period in anesthetized dogs.Transnasal pressure (PNA) and nasal resistance (RNA) were determined by use of artificial airflow (adjusted for body weight) for inspiration (PNAin and RNAin, respectively) and expiration (PNAout and RNAout). Procedures were repeated for the Beagles 7 days later.

Results—For the Beagles, mean ± SD of PNAin for both days (0.162 ± 0.042 kPa) was significantly lower than PNAout (0.183 ± 0.053 kPa). Similarly, RNAin (1.47 ± 0.41 kPa/[L/s]) was significantly lower than RNAout (1.64 ± 0.46 kPa/[L/s]). Pairwise comparison of values for PNA and RNA for the 2 days revealed no significant difference. Repeatability of the method (estimated as within-day variation) for RNA was ± 0.19 kPa/(L/s), whereas variation between the days was ± 0.36 kPa/(L/s) for RNAin and ± 0.44 kPa/(L/s) for RNAout. The 4 clinically normal Bulldogs had RNA values ranging from 1.69 to 3.48 kPa/(L/s), whereas in the 4 Bulldogs with respiratory problems, RNA ranged from 9.83 to 20.27 kPa/(L/s).

Conclusions and Clinical Relevance—RNA is inversely dependent on body size and nonlinearly associated with airflow. We propose that RNA in dogs should be determined for airflows standardized on the basis of body size. The PNA and RNA in Beagles can be measured with sufficient repeatability for clinical use and nasal obstructions are detectable.

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in American Journal of Veterinary Research


Objective—To evaluate the effects of shock wave treatment on cutaneous nerve function, compared with the effects of local nerve block and sedation.

Animals—18 clinically sound Swiss Warmbloods.

Procedure—Horses were randomly allocated to 3 groups and received different amounts and types of shock waves (extracorporeal shock wave treatment [ESWT] or radial pressure wave treatment [RPWT]). Horses were sedated with xylazine and levomethadone. Shock waves were applied to the lateral palmar digital nerve at the level of the proximal sesamoid bones on 1 forelimb. Skin sensitivity was evaluated by means of an electrical stimulus at the coronary band before and 5 minutes after sedation and at 4, 24, and 48 hours after application of ESWT or RPWT. On the contralateral forelimb, skin sensitivity was tested before and 10 minutes after an abaxial sesamoid nerve block.

Results—No significant changes in skin sensitivity were detected, regardless of the shock wave protocol applied. Mean reaction thresholds after sedation were more than twice the baseline thresholds. After the abaxial sesamoid block, no reaction was recorded in any of the horses.

Conclusions and Clinical Relevance—Application of ESWT or RPWT to the palmar digital nerve had no effect on cutaneous sensation distal to the treated region for at least 2 days after application. The analgesic effect of sedation on reaction to electrical stimuli was distinct but varied among horses. (Am J Vet Res 2005;66:2095–2100)

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in American Journal of Veterinary Research


OBJECTIVE To compare gait mechanics and limb loading in Icelandic horses tölting and trotting at equal speeds and estimate their impact on orthopedic health.

ANIMALS 12 orthopedically normal Icelandic horses.

PROCEDURES Kinetic and kinematic gait variables were simultaneously recorded as each horse was ridden at a tölt and trot on an instrumented treadmill at 3.4 m/s and 3.9 m/s. Differences between gaits were tested via 1-factor repeated-measures ANOVA.

RESULTS Horses had a higher stride rate and lower stride impulses at a tölt than at a trot. For forelimbs at a tölt, shorter relative stance duration resulted in higher peak vertical force (Fzpeak). Conversely, for hind limbs, longer relative stance duration resulted in lower Fzpeak. The higher head-neck position at a tölt versus trot caused no weight shift to the hind limbs, but a higher forehoof flight arc and lower proretraction movement were identified. Stance durations for forelimbs were briefer than for hind limbs at a tölt, and the inverse was observed at a trot. Minimal height of the horse's trunk at the point of Fzpeak of the respective limb suggested a spring-like mechanism for all limbs at a tölt. Hind limb measurements revealed no evidence of increased collection. Stride-to-stride limb timing varied more at a tölt than at a trot. At a trot, horses had brief or no suspension phases and a slightly 4-beated footfall rhythm was common. Post hoc energetic estimations revealed that tölting at the measured speeds was less advantageous than trotting.

CONCLUSIONS AND CLINICAL RELEVANCE High forelimb action in Icelandic horses and higher head-neck position at a tölt were associated with more restricted limb proretraction, higher Fzpeak, and faster force onset than at a trot. The impact of these differences on orthopedic health needs to be investigated more in detail.

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in American Journal of Veterinary Research


Urethral pressures profiles (upp) obtained by use of microtransducer catheters were determined in 8 anestrous sexually intact female Beagles during general anesthesia. A upp study consisted of 3 consecutive recordings, and 4 upp studies were repeated at an interval of 5 days in each dog. Maximal urethral pressure (cm of H2O), bladder pressure (cm of H2O), and anatomic urethral length (cm) were recorded. Maximal urethral closure pressure (cm of H2O) was calculated.

Mean ± sd (for all measurements) maximal urethral closure pressure was 12.8 ± 5.6 cm of H2O (range, 2.4 to 25.2 cm of H2O). Maximal urethral closure pressure was significantly (P < 0.05) decreased during the first recording period (11.4 ± 5.8 cm of H2O), compared with the second (13.0 ± 5.2 cm of H2O) or third (14.1 ± 5.7 cm of H2O) recording periods within a upp study (3 consecutive recordings). Mean maximal difference in urethral closure pressure during a single upp study was 4.8 ± 2.4 cm of H2O. Significant difference in maximal urethral closure pressure was not observed between studies.

Mean (for all measurements) anatomic urethral length was 6.2 ± 0.9 cm (4.1 to 7.8 cm). Anatomic urethral length was significantly (P < 0.05) less during the first recording period (6.1 ± 0.9 cm), compared with values for the second and third periods (6.3 ± 0.9cm, 6.4 ± 0.9 cm respectively). Anatomic urethral length for time 3 was significantly (P < 0.05) less than the value for time 1 (5.8 ± 0.7 cm vs 6.6 ± 0.8 cm).

We conclude that the microtransducer catheter technique for measurement of upp was reproducible during a single study and between successive studies.

This method is useful in documenting maximal urethral pressure, maximal urethral closure pressure, and anatomic urethral length in clinically normal sexually intact female dogs.

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in American Journal of Veterinary Research