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  • Author or Editor: Robert L. Linford x
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Summary

Quantitated locomotion analysis is increasingly being used during assessment and treatment of gait disorders in human beings. Locomotion analysis is also thought to have potential for enhancing the assessment of lameness in horses. Availability of highspeed video recording systems has simplified the process of quantitated locomotion analysis; however, the high cost of such systems has limited their use for routine clinical assessment in horses. The temporal resolution of 500- to 1,000-image/s (Hz) recording systems is beyond what has been considered necessary for precise quantitation of short-duration events in horses at the trot; however, it is uncertain whether the temporal resolution of more economical 60-Hz recording systems is adequate.

To determine whether a recording rate of 60 Hz is satisfactory for assessment of stride-timing values in horses at the trot, the stride-timing values calculated from 60-Hz recordings were compared with those calculated from 1,000-Hz recordings that had been simultaneously made for 5 horses trotting on a horizontal treadmill at a speed of 3.0 m/s. The left forefoot of each horse was fitted with an instrumented horseshoe that illuminated and quenched light-emitting diodes (led) in view of both cameras precisely at toe contact, heel contact, heel lift, and toe lift. The exact pattern and timing of foot placement and lift was referenced by the illumination pattern of the led. Recordings of 10 consecutive strides were reviewed, image by image for each horse, and the elapsed time at each important stride event was tabulated. Stride-timing values were then arithmetically calculated from the elapsed time values for each recording system.

Significant differences were not found between the stride-timing values obtained from the 1,000-Hz recordings and those obtained from the 60-Hz recordings for any timing variable assessed. For each timing variable, the mean value of the 60-Hz measurements for the 10 strides of each horse was within 3.3 milliseconds (ms) of the mean value of the 1,000Hz measurements for the same 10 strides, with the exception of the 60- and 1,000-Hz assessments of the toe-heel contact interval for 1 horse, which differed by 6.9 ms. On the basis of the 60- and 1,000-Hz recordings, the overall mean ± SD values for the stride, stance, swing, and breakover durations were, respectively, 731.4 ± 16.0 ms, 320.7 ± 15.2 ms, 410.7 ± 18.7 ms, and 60.5 ± 9.9 ms. The toe-heel contact interval was 7.6 ± 8.8 ms.

The instrumented shoe and led mechanism provided a unique, simple, and accurate method for quantitation of stride timing, with clear visual references for placement and lift. Using the shoe for optoelectronic assessment, it was found that a recording rate of 60 Hz was adequate to study stride-timing characteristics of horses trotting at 3.0 m/s when 10 strides were studied per horse. Temporal resolution of the 60-Hz recordings was not sufficient to study the foot-landing pattern for individual strides. Further studies are recommended to determine whether the 60-Hz rate is satisfactory for kinematic quantitation of timing and other stride variables. The optoelectronic methods that were used to assess stride timing in this study could readily be used in conjunction with kinematic studies to verify the accuracy of kinematic methods for quantitating stride-timing values. The cost of the 60-Hz video recording system used for this investigation was 30 times less than that of the 1,000-Hz system. Sixty-hertz video recording systems may provide a basis for increased usefulness and application of quantitated locomotion analysis techniques during clinical evaluation and treatment of gait disorders in horses.

Free access
in American Journal of Veterinary Research

SUMMARY

A cannulation technique was developed to collect blood samples from the ovarian vein of mares over an extended period. Ovarian venous cannulae placed in 4 mares remained patent for a mean (± sem) duration of 36.8 (± 6.2) days. During mid-diestrus, concentrations of progesterone in the ovarian vein ipsilateral to the corpus luteum (1,663.8 ± 238.8 ng/ml) were significantly (P < 0.001) higher than concentrations measured in paired samples from the jugular vein (6.1 ± 0.3 ng/ml). Concentration of estradiol in the ovarian vein ranged from a mean of 1,053.2 ± 303.1 pg/ml during diestrus to 3,353.8 ± 1,052.8 pg/ml during estrus, whereas values for 74% of samples collected concurrently from the jugular vein were near or below the sensitivity of the assay (10 pg/ml).

Results of the study indicate that patent long-term ovarian vein cannulation can be achieved in mares. The cannulation technique provides access to important fundamental information on equine reproductive endocrinology, which to our knowledge, has not been available.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

SUMMARY

Lameness examinations and radiography of the distal phalanx and associated soft-tissue structures of the front feet of 103 Thoroughbred racehorses, 4 to 9 years old, were performed to determine normal radiographic appearance and morphometry. Of 103 horses examined, 41 were used in the study that were without clinical signs of foot problems or lameness, had raced at least twice prior to radiography, and had raced at least twice more in the 6 months after radiography.

Lateromedial and dorsoproximal-palmarodistal radiographic views of each front distal phalanx were used to measure 28 bone and soft-tissue structures, and to evaluate 14 radiographic findings. Significant differences were not observed between left and right digits for any radiographic determination.

Mean thickness of the soft tissues dorsal to the distal phalanx, which provides an evaluation of the epidermal laminae, was 14.6 ± 1.0 mm when measured adjacent to the distal aspect of the distal phalanx. Most horses had straight, smooth hoof walls that were parallel to the dorsal cortex of the distal phalanx. The mean degree of palmar rotation of the distal phalanx was −0.5 ± 1.3, and none was rotated more than 4°.

The dorsal cortex was smooth and straight, without bone deposition or reaction in either digit for only 5 of the 41 horses. Active bone formation was seen unilaterally along the middle portion of the dorsal cortex in 7 horses, and along the distal portion of the dorsal cortex in 4 of the phalanges from 3 horses. New bone formation along the distal dorsal cortex was often accompanied by resorption of the palmar cortex. For 26 of the 31 horses without active bone deposition, smooth inactive bone formation along the midportion of the dorsal cortex was identified in 1 or both distal phalanges.

Bone at the solar margin of the distal phalanx was uniformly dense and finely trabeculated, without evidence of resorption or fractures. Severe irregularity of the solar margin was not found in any digit, and the margin of both phalanges was smooth in 8 horses. Various degrees of solar margin irregularity were observed in the other 33 horses.

The mean number of vascular canals within the distal phalanx was 8.4 ± 1.7, and the diameter of the largest canal was 3.4 ± 0.6 mm. A mean number of 2.0 ± 1.2 vascular canals was oriented parallel to the radiographic beam on the dorsoproximal-palmarodistal view, and these were termed end-on vessels, because they were visualized as radiolucent dots ≥ 1 mm in diameter in the central portion of the distal phalanx.

Racing performance of horses with subtle radiographic signs of laminitis (palmar rotation, hoof wall curvature or undulations, palmar cortical resorption, distal dorsal cortical bone deposition) was poorer than that of horses without these signs. These findings are suggestive of a subclinical laminitis condition, which may influence performance without causing overt clinical signs.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To compare ocular structures of Quarter Horses homozygous for hereditary equine regional dermal asthenia (HERDA) with those of Quarter Horses not affected by HERDA (control horses) and to determine the frequency of new corneal ulcers for horses with and without HERDA during a 4-year period.

Design—Cohort study of ocular structures and retrospective case series of horses with and without HERDA.

Animals—The cohort portion of the study involved 10 Quarter Horses with HERDA and 10 Quarter Horses without HERDA; the retrospective case series involved 28 horses with HERDA and 291 horses without HERDA.

Procedures—Ophthalmic examinations, Schirmer tear tests, tonometry, corneal pachymetry, histologic examinations, and scanning electron microscopy (SEM) were performed in cohorts of Quarter Horses with and without HERDA. Records were reviewed to determine the incidence of corneal ulcers in horses with and without HERDA during a 4-year period.

Results—Corneal thickness of horses with HERDA was significantly less than that of control horses, but tear production of horses with HERDA was significantly greater than that of control horses. Results of SEM revealed zones of disorganized, haphazardly arranged collagen fibrils in corneas of horses with HERDA that were not evident in corneas of control horses. The incidence of corneal ulcers was significantly greater for horses with HERDA than for horses without HERDA during the 4-year period.

Conclusions and Clinical Relevance—Alterations in corneal thickness, arrangement of collagen fibers, and incidence of corneal ulcers indicated that abnormalities in horses with HERDA were not limited to the skin.

Full access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine whether a maxillary nerve block via a modified infraorbital approach, applied before rhinoscopy and nasal biopsy of dogs, would decrease procedural nociception, minimize cardiorespiratory anesthetic effects, and improve recovery quality.

ANIMALS 8 healthy adult hound-type dogs

PROCEDURES In a crossover study, dogs received 0.5% bupivacaine (0.1 mL/kg) or an equivalent volume of saline (0.9% NaCl) solution as a maxillary nerve block via a modified infraorbital approach. A 5-cm, 20-gauge over-the-needle catheter was placed retrograde within each infraorbital canal, and bupivacaine or saline solution was administered into each pterygopalatine region. Rhinoscopy and nasal biopsy were performed. Variables monitored included heart rate, systolic arterial blood pressure (SAP), mean arterial blood pressure (MAP), diastolic arterial blood pressure (DAP), plasma cortisol and norepinephrine concentrations, purposeful movement, and pain scores. After a 14-day washout period, the other treatment was administered on the contralateral side, and rhinoscopy and nasal biopsy were repeated.

RESULTS SAP, MAP, and DAP were significantly higher for the saline solution treatment than for the bupivacaine treatment, irrespective of the time point. Plasma cortisol concentrations after saline solution treatment were significantly higher 5 minutes after nasal biopsy than at biopsy. Heart rate, norepinephrine concentration, purposeful movement, and pain score were not significantly different between treatments.

CONCLUSIONS AND CLINICAL RELEVANCE Maxillary nerve block via a modified infraorbital approach prior to rhinoscopy and nasal biopsy reduced procedural nociception as determined on the basis of blood pressures and plasma cortisol concentrations during anesthesia. These findings warrant further evaluation in dogs with nasal disease.

Full access
in American Journal of Veterinary Research