Search Results

You are looking at 1 - 4 of 4 items for :

  • Author or Editor: Douglas J. Weiss x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objectives

To determine whether pentoxifylline treatment altered hematologic, rheologic, electrolyte, or blood gas test results of Thoroughbreds during submaximal treadmill exercise.

Animals

5 healthy Thoroughbreds that had raced within the past year and had no history of exercise-induced pulmonary hemorrhage.

Procedure

Mixed venous blood samples were obtained before exercise, at treadmill speeds of 9 and 13 m/s, and 20 minutes after exercise; hematologic, rheologic, electrolyte, and blood gas test results were determined.

Results

Pentoxifylline treatment resulted in a 45% reduction in RBC filtration pressures for horses at rest. The improved RBC filterability persisted during treadmill exercise. Horses treated with pentoxifylline had a greater decrease in Po2 values and a lesser increase in plasma lactate concentration during treadmill exercise.

Conclusion

Administration of pentoxifylline improved RBC deformability of horses at rest and during treadmill exercise.

Clinical Relevance

Improved RBC deformability resulting from pentoxifylline treatment may reduce exercise-associated shear stress in pulmonary capillaries, thereby attenuating exercise-induced pulmonary hemorrhage. (Am J Vet Res 1996;57:1364-1368)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether furosemide treatment altered the blood flow properties and serum and RBC electrolyte concentrations of Thoroughbreds during submaximal treadmill exercise.

Design

Thoroughbreds were subjected to submaximal treadmill exercise with and without treatment with furosemide (1 mg/kg of body weight, IV).

Animals

5 healthy Thoroughbreds that had raced within the past year and had no history of exercise-induced pulmonary hemorrhage.

Procedure

Venous blood samples were obtained before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise, and hemorheologic and electrolyte test results were determined.

Results

Hemorheologic changes 60 minutes after furosemide administration included increased PCV, plasma total protein concentration, whole blood viscosity, mean RBC volume, and RBC potassium concentration, and decreased serum potassium concentration, serum chloride concentration, and RBC chloride concentration. Furosemide treatment attenuated the exercise-associated changes in RBC size, serum sodium concentration, serum potassium concentration, RBC potassium and chloride concentrations, and RBC density; exacerbated exercise-associated increases in whole blood viscosity; and had no effect on RBC filterability.

Conclusions

The hemorheologic effects of furosemide probably occurred secondary to total body and transmembrane fluid and electrolyte fluxes and would not improve blood flow properties.

Clinical Relevance

The beneficial effects of furosemide treatment in reducing the severity of bleeding in horses with exercise-induced pulmonary hemorrhage cannot be explained by improved blood flow properties. (Am J Vet Res 1996;57:891–895)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the contribution of hematocrit and RBC deformability to pulmonary vascular pressures of racehorses.

Design

Pony lungs were isolated and right and left lungs were perfused separately with blood. The effects of changing hematocrit and of pentoxifylline treatment were evaluated.

Animals

11 healthy mixed-breed ponies.

Procedure

Ponies were anesthesized, blood was collected, and lungs were removed and perfused with blood at constant flow rate.

Results

Increasing the hematocrit from 35% to 65% resulted in increases in pulmonary arterial pressure (53%, 45%), capillary shear stress (45%, 32%), and total vascular resistance (92%, 143%) at low (352 ± 33 ml/min) and high (1,442 ± 48 ml/min) flow rates, respectively. Pulmonary artery pressures were lower (10%, 11%) when lungs were perfused with blood from pentoxifylline-treated ponies, compared with blood from control ponies with low hematocrit (PCV, 30%) and low-flow rate and with high hematocrit (PCV, 45%) and high flow rate, respectively. Decreases in capillary shear stress and total vascular resistance were also observed for pentoxifylline-treated blood.

Conclusions

Increases in hematocrit equivalent to those occurring during competitive racing activity contribute substantially to pulmonary vascular pressures in horse lungs. Administration of pentoxifylline to ponies reduced RBC deformability and attenuated increases in pulmonary vascular pressures.

Clinical Relevance

Treatment of racehorses with pentoxifylline may reduce exercise-associated increases in pulmonary vacular pressure, thereby attenuating exercise-induced pulmonary hemorrhage.(Am J Vet Res 1996;57:346-350)

Free access
in American Journal of Veterinary Research

Summary

Hemorheologic alterations induced by incremental treadmill exercise were examined in 5 Thoroughbreds. Blood viscosity; pcv; rbc filterability, density gradient profile, and shape; serum and rbc electrolyte concentrations; and plasma total solids and lactate concentrations were measured before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise. Exercise was associated with significant (P < 0.05) increases in pcv, blood viscosity, and plasma total solids concentration. After adjustment of pcv to 40% by adding or removing each horse's own plasma, blood viscosity remained significantly greater in the sample obtained at 13 m/s, compared with that in samples taken at rest. Filterability of rbc was significantly decreased at 13 m/s, compared with values from other sampling times. During exercise, a significantly greater proportion of the rbc were less dense and were found in the upper layers of the rbc density gradient profile, compared with resting values. This change was associated with a significant increase in rbc mean cell volume. Rapid increases in serum sodium and potassium concentrations during exercise were accompanied by significant increases in rbc potassium and chloride concentrations. This study revealed a consistent pattern of hemorheologic alterations associated with exercise in Thoroughbreds, suggesting that multiple hemorheologic tests are needed to adequately define these complex alterations during exercise in horses.

Free access
in American Journal of Veterinary Research