Search Results

You are looking at 1 - 10 of 23 items for :

  • Refine by Access: All Content x
Clear All

Summary

Ten healthy sedentary male Thoroughbreds with previous race training experience were studied for 14 weeks. Horses were trained for 9 weeks, using a program designed after those used commonly in the United States. Horses were trained conventionally by slow trotting (250 m/min) for 2 weeks and galloping (390 to 450 m/min) for 4 weeks, followed by 3 weeks of galloping (440 to 480 m/min) and intermittent sprinting exercises (breezes) at distances between 600 and 1,000 m (900 to 950 m/min). The horses were then pasture rested for 5 weeks.

A standardized exercise test (set) involving an 800-m gallop at 800 m/min was administered before and after the 9-week training period and after the 5-week detraining period. Heart rate (hr) was monitored during exercise and at standardized intervals after exercise for 60 minutes. Venous blood for determination of plasma lactate concentration was obtained at 5 minutes after exercise.

Heart rate was monitored daily at rest, during exercise, and through the first 60 minutes of recovery. Venous plasma samples (for lactate determination) were obtained 5 minutes after the sprinting exercises. Horses were observed daily before exercise for signs of lameness and were not allowed to train if lame.

Differences after 9 weeks’ training were seen in the set recovery hr at 0.5 through 5 minutes after exercise (P < 0.05 to P < 0.01). Differences after detraining were seen in the set recovery hr at 40 and 60 minutes after exercise (P < 0.05 to P < 0.01). Neither training nor detraining resulted in differences in plasma lactate concentration after the set gallop.

A training-induced resting bradycardia was not observed. The mean maximal hr (hr max) during workouts was 238 ± 3.4 beats/min (n = 9). When exercise hr was expressed as a function of hr max, 22% of trotting, 89% of galloping, and 100% of sprinting workouts were performed at the ≥ 60% hr max. value characterized by the onset of blood lactate accumulation. Plasma lactate concentration further documented that all the sprinting exercises were performed with concentration above the point of onset of blood lactate accumulation. Mean postsprinting lactate concentration was not different over time and ranged from 13.4 ± 0.9 to 15.6 ± 0.6 mmol/L

As training progressed, some of the horses had days on which they were lame after exercise. Some lameness was judged sufficient to warrant phenylbutazone (pbz) administration. Retrospective analysis of the daily hr data indicated that there were no differences in hr during workouts for lame horses given pbz, compared with those not given pbz. Using analysis of variance, hr for horses that were lame during workouts was significantly higher than that for horses that were sound during workouts, during and 0.5 minutes after trotting; 0.5, 1, 2, 20, 40, and 60 minutes after galloping; and 0.5 and 20 minutes after sprinting (P < 0.05 to P < 0.01).

Free access
in American Journal of Veterinary Research

Abstract

Objective

To calculate normative joint moments of force and power for the forelimb of walking horses as a benchmark against which to compare these mechanical variables in horses with specific lameness.

Animals

4 Dutch Warmblood horses with no recent history of lameness.

Procedure

Horses were walked by hand through the test area, and data from 5 walking trials were collected for each horse. Two camera views were combined with vertical and craniocaudal ground reaction forces to calculate net moments of force in the sagittal plane across the carpal, metacarpophalangeal (fetlock), and distal interphalangeal (coffin) joints during the stance phase of the forelimb. Mechanical power was calculated as the product of net joint moment and the joint's angular velocity.

Results

During the early part of the stance phase, the carpal joint had oscillating periods of energy generation and absorption against a predominant flexor moment, then an absorption phase at the end of the stance phase, as the carpus flexed into swing against an extensor moment. The fetlock absorbed energy in the early part of the stance phase, then the terminal part was marked by a large generation of energy across the joint. A flexor moment was measured at the coffin joint throughout the stance phase, and this coincided with a long phase of energy absorption followed by a short phase of generation for push-off.

Conclusion

Consistency of the power data indicates that typical profiles of work exist for each of the joints (carpus, fetlock, and coffin).

Clinical Relevance

Detection of changes to these profiles of work may contribute to diagnosis of specific lameness conditions.(Am J Vet Res 1998;59:609–614)

Free access
in American Journal of Veterinary Research

SUMMARY

Starling forces and hemodynamics in the digits of 5 horses were studied during early laminitis induced by oral administration of an aqueous extract of black walnut (Juglans nigra). The black walnut extract was prepared from heartwood shavings and was administered by nasogastric tube. Heart and respiratory rates, rectal temperature, central venous and arterial pressures, digital pulses, and signs of lameness were monitored. Blood samples were collected for determination of wbc count, hemoglobin concentration, and pcv and for endotoxin and tumor necrosis factor assays. Total wbc count and central venous pressure were monitored until they decreased by 30 or 20%, respectively. These decreases in wbc count and central venous pressure were observed 2 to 3 hours after dosing with black walnut extract. Respiratory and heart rates, body temperature, systolic and diastolic blood pressures, pcv, and hemoglobin concentration did not change significantly.

Anesthesia was induced, heparin (500 IU/kg of body weight) was administered iv, and a pump-perfused extracorporeal digital preparation was established. Digital arterial and venous pressures were maintained at 100 and 30 mm of Hg, respectively. Blood flow, capillary pressure, lymph and plasma protein concentrations, and weight of the isolated digit during rapid increase in venous pressure were measured. Isogravimetric capillary filtration coefficient, vascular compliance, vascular and tissue oncotic pressures, tissue pressure, osmotic reflection coefficient, and precapillary and postcapillary resistances were calculated.

Mean digital blood flow was 14 ml/min/100 g, capillary pressure was 52 mm of Hg, and vascular compliance was 0.06 ml/mm of Hg. The vascular and tissue oncotic pressures were 21.49 and 4.93 mm of Hg, respectively. The osmotic reflection coefficient was 0.71, and tissue pressure was 41 mm of Hg. The precapillary and postcapillary resistances were 7 and 2 mm of Hg/ml, respectively. Capillary permeability to proteins was not significantly different from that previously measured in healthy horses, suggesting that the increased capillary filtration coefficient reflected increased capillary hydrostatic pressure and perfusion of previously nonperfused capillaries. Neither endotoxin nor serum tumor necrosis factor activity was detected in any samples. The hemodynamic and Starling forces observed in this study were similar to those observed after laminitis was induced by administration of a carbohydrate gruel. Significant differences between the 2 models were detected for total vascular resistance, postcapillary resistance, and capillary filtration coefficient. It is likely that these differences were identified because the horses administered the black walnut extract were at an earlier stage in the disease process. The findings of this study suggest that the increase in capillary pressure causes transvascular fluid movement, resulting in increased tissue pressure and edema. We hypothesize that further increases in tissue pressure may collapse capillary beds and lead to tissue ischemia.

Free access
in American Journal of Veterinary Research

. Horses were unshod, and their hooves were trimmed 1 week prior to the study. The horses were examined for lameness before and after each diet change, and they were excluded from the study at any time lameness was > 1 on a scale of 1 to 5. 8 Diets —The 3

Full access
in American Journal of Veterinary Research

animals. 18 Studies 22,23 have indicated that cattle deprived of adequate periods of sternal recumbency develop physiologic and behavioral signs of stress. There is also evidence that changes in lying behavior can be related to lameness 24,25 and that

Full access
in American Journal of Veterinary Research

score ≥ 2 were treated in accordance with a predetermined protocol and returned to their assigned pen. Any calf with signs of lameness or disease other than BRD was treated in accordance with common industry practices. Any calf that required treatment

Full access
in American Journal of Veterinary Research

breeds (7 warmblood horses, 2 ponies, and 1 Arabian) were used in this study. Mean ± SD age was 12 years ± 3.4 years (range, 7 to 20 years) and all horses were free of lameness and had no signs of acute illness or injury. Experimental procedures —The

Full access
in American Journal of Veterinary Research

veterinary hospital at the Redwings Horse Sanctuary. These veterinarians are involved in specialist equine practice on a daily basis and are experienced in diagnosing laminitis and differentiating this cause of lameness from other causes. Both sets of

Full access
in American Journal of Veterinary Research

, endotoxemia, or diseases of the digits as determined on the basis of results of a complete physical examination, CBC, lameness examination including hoof testing, and radiographic evaluation of the digits. The study was approved by the Institutional Animal

Full access
in American Journal of Veterinary Research

highest anion gap (41 mEq/L) was eliminated later in the ride because of metabolic failure and the horse with the lowest anion gap (34 mEq/L) was eliminated later in the ride because of lameness. Measuring lactate concentration immediately after a large

Full access
in American Journal of Veterinary Research