PubMed Health⌕ Search

Biomedical subjects

K W Hinchcliff

Publications and source records attributed to K W Hinchcliff.

At least 73 records · Page 4Linked to original sources
PubMed1998

Comparison of anion gap and strong ion gap as predictors of unmeasured strong ion concentration in plasma and serum from horses.

OBJECTIVE: To compare the accuracy of anion gap (AG) and strong ion gap (SIG) for predicting unmeasured strong ion concentration in plasma and serum from horses. ANIMALS: 6 well-trained Standardbred horses undergoing high-intensity exercise (experimental study) and 78 horses and ponies that underwent i.v. administration of lactic acid or endotoxin, and endurance, submaximal, or high-intensity exercise. PROCEDURE: Anion gap was calculated as AG = (Na+ + K+) - (Cl- + HCO3-), and SIG was calculated, using the simplified strong ion model, whereby SIG (mEq/L) = 2.24 x total protein (g/dl)/(1 + 10(6.65-pH)) - AG. The relation between AG or SIG and plasma lactate concentration was evaluated, using linear regression analysis. RESULTS: Linear relations between plasma lactate concentration and AG and SIG were strong for the experimental study (r2 = 0.960 and 0.966, respectively) and the published studies (r2 = 0.914 and 0.925, respectively). The following relations were derived: AG = 1.00 x plasma lactate + 10.5; SIG = 0.99 x plasma lactate + 2.8. An AG > 15 mEq/L indicated an increased unmeasured anion concentration, whereas a SIG < -2 mEq/L indicated an increased unmeasured strong anion concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Anion gap and SIG can be used to predict plasma lactate concentration in horses. AG is accurate and clinically useful for estimating unmeasured strong ion concentration in horses with total protein concentrations within or slightly outside reference range, whereas SIG is more accurate in horses with markedly abnormal total protein concentrations and those of various ages and with various concentrations of albumin, globulin, and phosphate.

Acid-Base Equilibrium↗
PubMed1998

Hepatic blood flow in horses during the recuperative period from maximal exercise.

OBJECTIVE: To determine effects of walking or standing on hepatic blood flow of horses after brief, intense exercise. ANIMALS: 6 adult Thoroughbreds (4 mares, 2 geldings). PROCEDURE: Horses were preconditioned on a treadmill to establish uniform level of fitness. Once fit, treadmill speed causing each horse to exercise at 120% of maximal oxygen consumption was determined and used in simulated races at 14-day intervals. In a three-way crossover study, horses were exercised at a speed inducing 120% of maximal oxygen consumption until fatigued or for a maximum of 2 minutes. Three interventions were studied: resting on the treadmill (REST), exercised then standing on the treadmill for 30 minutes (MS), and exercised then walking at 2 m/s for 30 minutes (MW). At 60 seconds after completion of exercise, bromsulphalein (BSP) was infused IV, and blood samples were collected every 2 minutes for 30 minutes for analysis of BSP concentration. Hematocrit and plasma total solids concentration were measured. Pharmacokinetic parameters were derived, using nonlinear regression, and were compared, using Friedman's repeated measures analysis on ranks. RESULTS: Plasma BSP concentration was higher after exercise. Median hepatic blood flow (BSP clearance) decreased significantly from 23.8 (REST) to 20.7 (MS) and 18.7 (MW) ml/min/kg. Median steady-state volume of distribution of BSP decreased from 47.6 (REST) to 42.7 (MW) and 40.2 (MS) ml/kg. Differences among trials were not significant when horses walked or stood after exercise. CONCLUSIONS: Hepatic blood flow and pharmacokinetics of BSP are markedly altered immediately after exercise. Limiting movement of horses during this period did not affect hepatic blood flow.

Animals↗
PubMed1998

Intensity-dependent effects of acute submaximal exercise on the pharmacokinetics of bromsulphalein in horses.

OBJECTIVE: To determine the effects of acute exercise on hepatic blood flow by studying hepatic clearance of bromsulphalein for several submaximal exercise intensities. ANIMALS: 8 adult Standardbred mares. PROCEDURE: Horses were subjected to 4 submaximal exercise intensities (resting and 40, 60, and 80% maximal oxygen consumption). After horses had been running at the required treadmill speed for 1 minute, bromsulphalein (BSP; 5 mg/kg of body weight, IV) was administered during a 45- to 60-second period, and horses continued at the desired speed for an additional 15 minutes. Blood samples were collected at 2-minute intervals for 30 minutes, and plasma concentration of BSP was determined by spectrophotometry. Estimates of pharmacokinetic variables were compared among the 4 exercise intensities, using a Friedman repeated-measures analysis on ranks and linear regression. RESULTS: Median values for clearance of BSP from blood and plasma decreased significantly with exercise and was linearly related to exercise intensity. Exercise-induced differences were not detected in the volume of distribution of BSP. Elimination half-life of BSP increased significantly with increasing exercise intensity and was linearly related to exercise intensity. CONCLUSIONS: Acute submaximal exercise has a dramatic effect on clearance of BSP in horses. Presumably, exercise-induced decreases in splanchnic blood flow limit blood flow to the liver, decreasing hepatic clearance of BSP and leading to persistence of plasma concentrations of BSP. CLINICAL IMPLICATIONS: Drugs that are efficiently extracted by the liver may have decreased hepatic clearance when horses exercise at submaximal intensities.

Animals↗
PubMed1997

Electrocardiographic characteristics of endurance-trained Alaskan sled dogs.

OBJECTIVE: To determine electrocardiographic characteristics of endurance-trained Alaskan sled dogs. DESIGN: Case series. ANIMALS: 319 Alaskan sled dogs entered to compete in the 1994 Iditarod Trail Sled Dog Race. PROCEDURE: ECG were recorded while dogs were standing and were analyzed digitally. RESULTS: Amplitudes of P waves (median, 0.40 mV; fifth to 95th percentile range, 0.11 to 0.61 mV) and R waves in lead II (median, 3.02 mV; fifth to 95th percentile range, 1.49 to 4.40 mV) were high; durations of P waves in lead II (median, 61 milliseconds; fifth to 95th percentile range, 36 to 96 milliseconds), QRS complexes (median, 64 milliseconds; fifth to 95th percentile range, 52 to 80 milliseconds), and QT intervals (median, 236 milliseconds; fifth to 95th percentile range, 208 to 277 milliseconds) were prolonged. Median value for mean axis of ventricular depolarization was 57 degrees (fifth to 95th percentile range, 19 to 90 degrees). Atrial and ventricular premature depolarizations were observed in 3 (0.9%) and 4 (1.3%) of 319 dogs, respectively, and paroxysmal ventricular tachycardia was detected in 1 (0.3%). CLINICAL IMPLICATIONS: Results suggest that electrocardiographic characteristics of endurance-trained Alaskan sled dogs differ from those reported for nonsled dogs, probably as a result of effects of endurance training on heart size. Some of these characteristics could be mistaken as evidence of pathologic cardiac hypertrophy.

Alaska↗
PubMed1997

Effect of racing on serum sodium and potassium concentrations and acid-base status of Alaskan sled dogs.

OBJECTIVE: To examine the effect of participation in a long-distance race on serum electrolyte concentrations, estimated exchangeable cation content, and acid-base status of Alaskan sled dogs. DESIGN: Prospective study. ANIMALS: 9 male and 5 female, sexually intact, physically fit Alaska sled dogs between 18 and 48 months old. PROCEDURE: Body weight was recorded, and blood samples were collected from dogs before, during, and after a 300-mile race. RESULTS: Serum sodium and potassium concentrations decreased during the race, as did serum total protein, albumin, and globulin concentrations and PCV. Effects on acid-base status were minimal. Body weight and estimated total exchangeable cation content in dogs also decreased significantly during the race. CLINICAL IMPLICATIONS: Prolonged running is associated with decreases in serum cation concentration and estimated total exchangeable cation content in dogs, as in human beings and horses. However, the mechanism of the decrease in serum cation concentration likely differs among species. Clinical abnormalities associated with cation depletion were not observed in the dogs in this study.

Acid-Base Equilibrium↗
PubMed1997

Seroprevalence of antibodies to Sarcocystis neurona in horses residing in Ohio.

OBJECTIVE: To determine the seroprevalence of serum antibodies to Sarcocystis neurona in horses residing in Ohio. DESIGN: Prevalence survey. SAMPLE POPULATION: Serum from samples from 1,056 horses. Serum was collected on every 36th sample submitted to the Ohio State Diagnostic Laboratory for testing for equine infectious anemia. PROCEDURE: Serum was frozen at -80 C and analyzed for antibodies to S neurona, using a western blot. Information regarding blood sample collection, age, breed, sex, and geographic location was recorded for each horse. Data were analyzed, using multivariable logistic regression. RESULTS: Horses of 37 breeds from 81 of Ohio's 88 counties were included in the study population. There were 481 females, 133 males, and 442 geldings ranging in age from 3 months to 27 years; > 48% were < 5.6 years old. More than 53% of samples were seropositive for antibodies to S neurona. A gender or breed effect on seroprevalence was not identified. There was a significant effect of age (P < or = 0.0001; with older horses more likely to be affected), and of location (statistical and extension districts; P = 0.02 and P = 0.03, respectively) on seroprevalence. Location effects appeared to be correlated to the number of days with temperatures below freezing (P < 0.05). CLINICAL IMPLICATIONS: The high seroprevalence of antibodies to S neurona found in the sample population emphasizes the importance of examining CSF for S neurona-specific antibodies when establishing a diagnosis of equn protozoal myeloencephalitis.

Age Distribution↗
PubMed1997

Exercise-associated hyponatremia in Alaskan sled dogs: urinary and hormonal responses.

Exercise-associated hyponatremia occurs in horses and humans, both species that sweat, and in sled dogs, which do not sweat. To investigate the mechanism of exercise-associated hyponatremia in sled dogs, we measured water turnover, serum electrolyte concentrations and osmolality, plasma renal hormone concentrations, and urine composition of 12 fit Alaskan sled dogs before, during, and after a 490-km sled dog race (Ex group). Water turnover and serum electrolyte concentrations were measured in six similarly fit dogs that did not run (Sed group). Water turnover was significantly larger (P < 0.001) in Ex [190 +/- 19 (SD) ml . kg-1 . day-1] than in Sed dogs (51 +/- 13 ml . kg-1 . day-1). There were significant (P < 0.001) decreases in serum sodium concentration (from 148.6 +/- 2.8 to 139.7 +/- 1.9 mmol/l) and osmolality (from 306 +/- 9 to 296 +/- 5 mosmol/kgH2O) of Ex, but not Sed, dogs during the race. Plasma concentrations of arginine vasopressin decreased, whereas aldosterone and plasma renin activity increased significantly (P < 0. 01) during the race. Urine osmolality was unchanged, whereas urine sodium, potassium, and chloride concentrations decreased significantly (P < 0.05) and urine urea concentration increased (P = 0.06). These results demonstrate increased water turnover associated with hyponatremia and renal sodium conservation with maintained high urine osmolality in exercising Alaskan sled dogs.

Animals↗
PubMed1997

Effect of furosemide and subsequent intravenous fluid administration on right atrial pressure of splenectomized horses.

OBJECTIVE: To investigate the effect of i.v. administration of fluids on the furosemide-induced reduction in right atrial pressure (RAP) and relative change in blood volume (BV) of splenectomized mares. ANIMALS: 5 splenectomized mares. PROCEDURE: RAP was measured by use of a micromanometer placed in the right atrium. Jugular venous blood was collected for measurement of hematocrit, plasma total protein concentration, and hemoglobin concentration. Right atrial pressure was recorded and blood samples were collected immediately before furosemide (1 mg/kg of body weight, i.v.) administration, then every 15 minutes for 240 minutes. Beginning 120 minutes after furosemide administration, polyionic fluids (lactated Ringer's solution) were administered (2 L q 15 min) for 120 minutes. RESULTS: Furosemide induced a significant (P < 0.05) decrease in mean RAP (7.6 +/- 1.5 and 3.2 +/- 1.2 mm of Hg before and 15 minutes after furosemide administration, respectively), and BV (8.4 +/- 1.1 % by 15 minutes). Polyionic fluid administration restored RAP and BV. The volume of polyionic fluids administered (32 +/- 2 ml/kg) was not significantly different from the volume of urine produced (38 +/- 7.8 mg/kg). Difference was not apparent in the relation between change in BV and RAP before or after fluid administration. CONCLUSIONS: The effect of furosemide on RAP of horses is mediated in large part by furosemide-induced reduction in BV. However, an effect of furosemide on venous compliance cannot be excluded as contributing to the reduction in RAP.

Analysis of Variance↗
PubMed1997

Effect of sodium bicarbonate administration on blood constituents of horses.

OBJECTIVE: To describe changes in blood constituents of horses after oral and i.v. administration of sodium bicarbonate (NaHCO3), and to determine whether the changes are dose dependent. ANIMALS: 6 adult Standardbred mares. PROCEDURE: 3 oral doses (1,500, 1,000, and 250 mg/kg of body weight) or 1 intravenous dose (250 mg/kg, 5% solution) of NaHCO3 in 3 L of water, or water (3 L orally), were given to the mares; then changes in blood constituents were measured. Access to food and water was denied during the experiment. Blood samples were collected immediately before treatment and at hourly intervals for 12 hours after treatment, and were analyzed for blood gas tensions; serum osmolality; serum sodium, potassium, chloride, and creatinine concentrations; PCV; and total solids concentration in plasma. RESULTS: All NaHCO3 treatments induced significant (P < 0.05) metabolic alkalosis, hypernatremia, hypokalemia, and hyperosmolality for at least 8 hours. In mares given the 1,500- and 1,000-mg doses of NaHCO3 orally, hypercapnia persisted for at least 12 hours, whereas hypercapnia lasted 2 hours in mares given the 250-mg dose orally or i.v. (P < 0.05). A tendency for reduction in PCV, proteins in plasma concentration, and serum concentration of chloride was observed 1 hour after i.v. administered doses of NaHCO3. CONCLUSIONS: Oral or i.v. administration of NaHCO3 (> or = 250 mg/kg) to resting horses without ad libitum access to water induces significant and persistent acid-base and electrolyte changes.

Acid-Base Equilibrium↗
PubMed1997

Effect of sodium bicarbonate administration on renal function of horses.

OBJECTIVE: To describe changes in renal function of horses after oral and i.v. administration of sodium bicarbonate (NaHCO3) and to determine whether changes are dose dependent. ANIMALS: 6 Standardbred mares. PROCEDURE: Blood and urine samples for determination of renal function were collected immediately before and at hourly intervals for 12 hours after administration of each of 3 oral doses (1,500, 1,000 and 250 mg/kg of body weight, in 3 L of water) and 1 i.v. dose (250 mg/kg, 5% solution) of NaHCO3, or water (3 L orally). RESULTS: NaHCO3 induced increases in urine flow; electrolyte-free water reabsorption; urine concentrations of sodium and bicarbonate; fractional excretion of sodium, potassium, chloride, and bicarbonate; urinary excretion and clearance of sodium and bicarbonate; urine pH and anion gap; and mean plasma concentration of antidiuretic hormone. NaHCO3 induced attenuation in reduction with time of urine excretion and clearance of potassium, chloride, and osmoles, and induced reduction in urine osmolality. Plasma aldosterone and atrial natriuretic peptide concentrations and glomerular filtration rate were not modified. CONCLUSIONS: Renal responses to NaHCO3 load emphasize conservation of plasma volume and reestablishment of acid-base balance over control of hyperosmolality by diuresis, natriuresis, and increased bicarbonaturia. These responses imply a large fluid shift from the extravascular space to the vascular compartment, which was eliminated via diuresis, thus preventing hypervolemia.

Acid-Base Equilibrium↗
PubMed1997

Cardiorespiratory and metabolic effects of walking, standing, and standing with a splint during the recuperative period from maximal exercise in horses.

OBJECTIVE: To determine the effects of walking, standing, or standing with a splint on 1 forelimb on rate of recuperation of horses after a brief, intense bout of exercise. ANIMALS: 6 adult Thoroughbreds (435 to 542 kg). PROCEDURE: Horses were preconditioned by exercise on a treadmill to establish a uniform level of fitness. Once fit, the treadmill speed causing each horse to exercise at 120% of its maximal oxygen consumption was determined and was used in simulated races at 14-day intervals. Horses were instrumented for collection of arterial and mixed venous blood samples for measurement of acid-base status, concentrations of metabolites, and cardiopulmonary indices. The horses were exercised at a speed inducing 120% of their maximal oxygen consumption until fatigued or for a maximum of 2 minutes. Three recuperative interventions were evaluated: walking at 1.8 m/s for 30 minutes, then standing for the remainder of the 90-minute trial; standing stationary for 90 minutes; and standing stationary for 90 minutes with a splint on the right forelimb. RESULTS: Walking significantly increased cardiac output during the recuperative phase and hastened recovery of normal acid-base status and return of blood lactate concentration to baseline values. CONCLUSION: Limiting movement of horses during the recuperative period delays recovery from maximal exercise. Most measured indices returned to baseline by 60 minutes after exercise. All measured cardiopulmonary indices returned to baseline values by 90 minutes after exercise. CLINICAL RELEVANCE: Horses that are not allowed to walk during recuperation from exercise may have a prolonged recovery period.

Acid-Base Equilibrium↗
PubMed1997

Effect of combined staphylectomy and laryngotomy on upper airway mechanics in clinically normal horses.

OBJECTIVE: To investigate the effect of combined staphylectomy and laryngotomy on upper airway mechanics in clinically normal horses running on a treadmill. ANIMALS: 6 Standardbreds. PROCEDURE: Upper airway mechanics were measured with horses trotting or pacing on a treadmill at 5, 8, and 10 m/s before and 6 weeks after combined staphylectomy and laryngotomy. Pharyngeal and tracheal inspiratory and expiratory pressure were measured by use of transnasal tracheal and pharyngeal side hole catheters connected to differential pressure transducers. A pneumotachograph mounted on the rostral end of an airtight face mask was used to measure airflow. RESULTS: Upper airway and translaryngeal inspiratory impedances were higher, respiratory rate was decreased, and inspiratory time was longer (P < 0.05) at all speeds after staphylectomy and laryngotomy. CONCLUSION: Combined staphylectomy and laryngotomy significantly affects upper airway mechanics in clinically normal horses. CLINICAL RELEVANCE: Because combined staphylectomy and laryngotomy exerts a potentially adverse effect on upper airway mechanics in clinically normal horses, the procedure should only be performed when it is clearly indicated.

Animals↗
PubMed1997

Metabolizable energy intake and sustained energy expenditure of Alaskan sled dogs during heavy exertion in the cold.

OBJECTIVE: To measure energy expenditures of Alaskan sled dogs at rest and during racing under frigid conditions, using the doubly labeled water (DLW) technique. ANIMALS: 18 fit Alaskan sled dogs. PROCEDURE: Energy expenditure was measured in 9 dogs during a 490-km sled dog race by use of the DLW technique, whereby dogs were administered water enriched with nonradioactive isotopes of hydrogen and oxygen. Energy intake was determined by dietary analysis. Changes in background abundance of the isotopes 2H and 18O were monitored in 5 dogs that did not receive isotope-enriched water. RESULTS: Dogs completed the 490-km race at an average speed of 7 km/h at ambient temperature of -35 to -10 C. Total energy expenditure, measured by the DLW technique, was 47,100 +/- 5,900 kJ/d (4,400 +/- 400 kJ.kg-0.75/d), and metabolizable energy intake was 44,600 kJ/d (4,100 kJ.kg-0.75/d) during the 70-hour race. CONCLUSIONS: The sustained metabolic rate for these sled dogs during racing was extraordinarily high for a large mammal. This study validated use of the DLW technique in dogs with exceptionally high energy expenditure associated with prolonged exercise in the cold.

Animals↗
PubMed1996

Cervical meningomyelocele associated with spina bifida in a hydrocephalic miniature colt.

Cervical meningomyelocele, spina bifida, and hydrocephalus were diagnosed in a newborn miniature colt that was unable to stand and had a cystic mass in the caudal portion of the dorsal cervical region. Results of physical examination and ultrasonographic imaging of the brain supported the diagnosis of hydrocephalus. Results of radiographic evaluation of the vertebral column were consistent with spina bifida at C5-C6. Fluid aspirated from the cervical mass resembled CSF. Radiography of the cervical region after injection of iohexol into the mass revealed herniation of the spinal cord through a large bony defect, supporting the diagnosis of spina bifida and meningomyelocele. Meningomyelocele, spina bifida, and hydrocephalus are interrelated congenital anomalies in other species. Meningomyelocele should be suspected in foals that have neurologic abnormalities, especially if they have other congenital anomalies and a fluid-filled mass along the dorsal midline.

Animals↗
PubMed1996

Factors associated with finishing status for dogs competing in a long-distance sled race.

OBJECTIVE: To determine whether selected factors were associated with finishing status in a long-distance sled dog race. DESIGN: Prospective, observational study. ANIMALS: 248 dogs participating in the 1994 Iditarod trail sled race that were members of 13 teams that finished the race. Dogs were not selected randomly, but were members of teams that were easily accessible for examination before the race. The proportion of teams that were examined that finished the race (14/17) was similar to the proportion of teams that were not examined that finished the race (36/41). PROCEDURE: Age, sex, body conformation (weight, length, and thoracic width and circumference), cardiac variables (heart rate, natural logarithm of heart period variance, PR interval, QRS duration, QT index, R wave amplitude in leads II and V3, mean electrical axis, presence of cardiac arrhythmias suggestive of myocardial disease), and athletic ranking as assessed by the musher were compared between dogs that finished the race (n = 128) and dogs that did not finish (n = 120). RESULTS: The only factor found to differ significantly (P < 0.05) between finishers and nonfinishers was athletic ranking as assessed by the musher. Athletic rank and QRS duration or QRS duration normalized for body weight were identified by means of logistic regression as variables associated (P < 0.15) with finishing status. There was a significant (P < 0.0001), but weak (R2 = 0.18), linear relationship between race time and mean QRS duration for each team. CLINICAL IMPLICATIONS: Athletic ranking as assessed by the musher was the most important of the studied variables in determining finishing status, whereas age, sex, body conformation, and body weight were unimportant. Duration of the QRS was of minor importance in determining finishing status.

Animals↗
PubMed1996

Performance failure in Alaskan sled dogs: biochemical correlates.

Many dogs competing in long distance sled dog races do not complete the race. In this study the plasma biochemical variables of dogs that completed a long distance sled race were compared with those of dogs that did not complete the race. Blood samples were collected from dogs completing the race and from retired dogs, within six hours of their finishing or retiring. The plasma concentrations of magnesium, phosphate and triglyceride and the plasma activities of alkaline phosphatase and alanine aminotransferase were significantly (P < 0.003) greater in the dogs that retired than in the dogs that completed the race. Dogs that finished had significantly higher (P < 0.003) plasma urea nitrogen and uric acid concentrations and gamma-glutamyl transpeptidase activity than dogs that retired. These differences were judged not to be clinically significant. The dogs that retired showed no evidence of dehydration, significant plasma electrolyte abnormalities, or myopathy.

Animals↗
PubMed1996

Phenylbutazone increases right atrial pressure and heart rate of running horses.

The effect of inhibition of cyclooxygenase activity on the hemodynamic response to exertion was examined in 6 horses. Rates of O2 consumption and CO2 production and carotid, pulmonary arterial, and right atrial pressures were measured while the horses performed a standardized exercise test on a treadmill after treatment with phenylbutazone or a placebo. Phenylbutazone (8.8 mg/kg p.o. for 2 days and 4.4 mg/kg i.v. 60 min before exertion) abolished the exertion-induced increases in plasma 6-ketoprostaglandin F1 alpha and thromboxane B2 concentrations, confirming inhibition of cyclooxygenase activity. Phenylbutazone treatment resulted in significantly (P < 0.05) higher heart rates and right atrial pressures during exertion than did treatment with placebo, which may have been due to increased myocardial sensitivity to sympathetic stimulation and/or decreased venous compliance. There was not a detectable effect of phenylbutazone on carotid or pulmonary arterial pressures, O2 consumption, CO2 production, or blood lactate concentration. Changes in plasma volume during exertion were not influenced by phenylbutazone. These results demonstrate that cyclooxygenase products likely mediate or modulate some of the systemic hemodynamic responses to exertion in horses.

6-Ketoprostaglandin F1 alpha↗