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Biomedical subjects

K W Hinchcliff

Publications and source records attributed to K W Hinchcliff.

125 records · Page 7Linked to original sources
PubMed1990

Renal and systemic hemodynamic responses to sustained submaximal exertion in horses.

We investigated the effects of 1 h of sustained submaximal exertion on the renal and systemic hemodynamics of six horses. The horses ran on a treadmill at a speed that produced heart rates of 55-60% of each horse's maximum heart rate. Exertion produced heart rates of 121 +/- 6.6 and 126 +/- 6.1 (SE) beats/min after 15 and 60 min, respectively. Cardiac output increased significantly (P less than 0.05) from 70.1 +/- 3.1 to 246.2 +/- 4.7 ml.min-1.kg body wt-1 after 15 min of exertion and thereafter did not change. There was no significant change from rest in p-aminohippuric acid and creatinine clearances, filtration fraction, or renal blood flow during exertion. Plasma total solid concentration and hematocrit increased by 3.8 and 8.6%, respectively, between 20 and 60 min of exertion. Pulmonary artery temperature increased significantly from 37.6 degrees C at rest to 38.6 degrees C at 60 min of exertion. This study demonstrates the ability of the horse to maintain renal hemodynamics similar to resting values and systemic hemodynamics at steady-state values despite hemoconcentration and increased body temperature during sustained submaximal exertion.

Animals↗
PubMed1990

Changes in coagulation and fibrinolysis in horses during exercise.

Changes in clotting time (CT) and fibrinolytic activity (FA) were evaluated in 6 mature, female horses during exercise. Two trials were performed on consecutive days, using a randomized crossover design. Each mare was assigned to either an exercise trial or a control trial on the first day, and to the alternate trial 24 hours later. Mares exercised for 20 minutes on a treadmill at an elevation of 2 degrees and a velocity of 5 m/s. Venous blood samples were collected immediately before exercise, at 4, 8, 12, 16 and 20 minutes during exercise, and 15 minutes after cessation of exercise. Blood was placed into plain glass tubes for determination of CT, and into chilled, citrated tubes for determination of FA, plasminogen/plasmin complex activity (PLG), one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), and antithrombin-III (AT-III) activity. There were significant differences (P less than 0.05) between the control and exercise groups for CT, FA, and PLG. During exercise, clotting time decreased from 21.5 +/- 1.6 minutes to 9.9 +/- 1.6 minutes (mean +/- SD; P less than 0.05), without significant changes in OSPT, APTT, or AT-III. Fibrinolytic activity and PLG increased (P less than 0.05) during exercise. Changes in CT, FA, and PLG were significant at 4 minutes of exercise, remained altered until the end of exercise, and returned to baseline values by 15 minutes of recovery. Clotting time, OSPT, APTT, FA, AT-III, and PLG did not change (P greater than 0.05) during control trials.

Animals↗
PubMed1989

Cerebrospinal fluid eosinophilia and ataxia in five llamas.

Cerebrospinal fluid eosinophilia was associated with ataxia in five llamas. A presumptive diagnosis of cerebrospinal parasitism was made, and a response to combined anthelmintic and anti-inflammatory therapy was seen in each animal. The results demonstrate the value of an examination of cerebrospinal fluid in the evaluation of neurological disease in llamas.

Animals↗
PubMed1989

Phenolsulfonphthalein pharmacokinetics and renal morphologic changes in adult pony mares with gentamicin-induced nephrotoxicosis.

Changes in renal function, determined by pharmacokinetics of phenolsulfonphthalein (PSP), and renal morphologic features were examined in adult pony mares given 20 mg of gentamicin sulfate/kg of body weight, IV, q 8 h (group A) n = 7 or isotonic saline solution, IV, q 8 h, n = 5 (group B) for 14 days. Susceptibility of ponies to gentamicin-induced nephrotoxicosis was varied. Two group-A ponies developed acute renal failure and were euthanatized before treatment day 14, whereas 5 group-A A ponies did not develop physical or behavioral abnormalities after 14 days of gentamicin administration. All group-A ponies but none of group-B ponies developed ultrastructural abnormalities of the proximal tubular epithelium, consistent with gentamicin-induced nephrotoxicosis. Significant (P less than 0.05) differences were not detected in pharmacokinetic values of either group. Clearance of PSP was reduced in 4 group-A ponies that developed the most severe gentamicin-induced nephrotoxicosis. Changes in clearance of PSP were significantly (P less than 0.05) correlated with changes in the serum creatinine concentration.

Animals↗
PubMed1988

Gentamicin-induced nephrotoxicosis in a cow.

Gentamicin-induced nephrotoxicosis developed in a mature Holstein cow without evidence of preexisting renal disease. Factors possibly predisposing to the nephrotoxicosis included coadministration of a nonsteroidal anti-inflammatory drug and severe gram-negative bacterial sepsis. The cow recovered after prolonged hospitalization.

Acute Kidney Injury↗
PubMed1988

Jejunojejunal intussusception associated with a transmural adenocarcinoma in an aged cow.

After 3 days of intestinal obstruction, a proximal jejunojejunal intussusception was resected during surgery in an adult Holstein cow. A transmural adenocarcinoma was found at the proximal margin of the intussusception. The cow recovered well from surgery and produced milk and embryos to expectation. During the seventh month after surgery, the cow developed pneumonia and, therefore, was euthanatized. Disseminated abdominal and thoracic neoplasia was observed at necropsy.

Adenocarcinoma↗
PubMed1987

Pharmacokinetics of phenolsulfonphthalein in horse and pony mares.

Pharmacokinetics of phenolsulfonphthalein (PSP) in horse and pony mares was determined after injection of 1 mg/kg of body weight, IV. A plasma PSP concentration vs time curve was described adequately in horses and ponies by an open, 2-compartment model. There were significant differences in the elimination phase parameters, apparent volume of distribution at steady state, and apparent volume of distribution of horses and ponies. The harmonic mean elimination half-life of PSP in horses was significantly longer (P less than 0.001) than that in the ponies (16.4 and 10.0 minutes, respectively). The mean plasma clearance of PSP in horses was significantly (P less than 0.05) less than that in ponies (0.00554 and 0.00701 L/min/kg, respectively). There was no difference between horses and ponies in the metabolic clearance of PSP. The fraction of the administered dose of PSP excreted in the urine in the first 15 minutes was not significantly different between horses and ponies.

Animals↗
PubMedDate not supplied

Hemodynamic effects of atropine, dobutamine, nitroprusside, phenylephrine, and propranolol in conscious horses.

The authors investigated the cardiovascular effects of low doses of nitroprusside, dobutamine, and phenylephrine and a beta-adrenergic blocking dose of propranolol in conscious, healthy horses with and without prior atropine administration. A parasympathetic blocking dose of atropine produced significant increases in heart rate and arterial pressures, and decreased stroke volume, ejection fraction, pulse pressure, and right-ventricular end-diastolic pressure and volume. Cardiac output was not changed by atropine administration. Nitroprusside reduced arterial pressures to a greater extent in atropinized horses but increased heart rate in both atropinized and non-atropinized horses. Dobutamine increased mean arterial pressure in both non-atropinized and atropinized horses but increased heart rate, diastolic arterial pressure, and systemic vascular resistance only in atropinized horses. Propranolol did not affect any of the hemodynamic variables that were measured. Phenylephrine, in the presence of beta-adrenergic blockade, increased mean arterial pressure and reduced cardiac output. This study showed that low doses of nitroprusside, dobutamine, and phenylephrine produce significant hemodynamic effects in conscious, healthy horses and that these effects are modified by prevailing parasympathetic tone.

Animals↗
PubMedDate not supplied

Pharmacology of furosemide in the horse: a review.

Furosemide, a diuretic, is frequently administered to horses for the prophylaxis of exercise-induced pulmonary hemorrhage and the treatment of a number of clinical conditions, including acute renal failure and congestive heart failure. Furosemide increases the rate of urinary sodium, chloride, and hydrogen ion excretion. Plasma potassium concentration decreases after furosemide administration but urinary potassium excretion in horses is minimally affected. Renal blood flow increases after furosemide administration. Systemically, furosemide increases venous compliance and decreases right atrial pressure, pulmonary artery pressure, pulmonary artery wedge pressure, and pulmonary blood volume. The systemic hemodynamic effects of furosemide are only manifest in the presence of a functional kidney, but can occur in the absence of diuresis, emphasizing the importance of the renal-dependent extra-renal effects of furosemide. The renal and systemic hemodynamic effects of furosemide are modified by prior administration of nonsteroidal anti-inflammatory drugs. Furosemide administration attenuates exercise-induced increases in right atrial, aortic, and pulmonary artery pressures in ponies. Furosemide prevents exercise and allergen-induced bronchoconstriction in humans and decreases total pulmonary resistance in ponies with recurrent obstructive airway disease. These pharmacologic effects are frequently used to rationalize its questionable efficacy in the prevention of exercise-induced pulmonary hemorrhage. Neither the effect of furosemide on athletic performance nor its efficacy in the prevention of exercise-induced pulmonary hemorrhage has been convincingly demonstrated.

Animals↗
PubMedDate not supplied

Heparin: a review of its pharmacology and therapeutic use in horses.

Heparin is used clinically in horses to treat hemostatic abnormalities associated with severe gastrointestinal disease, septicemia, and endotoxemia. The primary anticoagulant effect of heparin is through the suppression of thrombin-dependent amplification of the coagulation cascade, and inhibition of thrombin-mediated conversion of fibrinogen to fibrin. Heparin may be of benefit in preventing the complications associated with hypercoagulable states such as jugular vein thrombosis, laminitis, and organ failure. Heparin may also be beneficial in the prevention of intraabdominal adhesions after gastrointestinal surgery, and in amelioration of hemodynamic abnormalities associated with endotoxic shock. Because a sequential rise in serum heparin concentration occurs during a uniform dosage regimen, a decreasing dosage regimen is recommended. The initial dose recommended is 150 U heparin/kg body weight subcutaneously, followed by 125 U heparin/kg body weight subcutaneously, every 12 hours for six doses. The dose should be decreased to 100 U heparin/kg body weight subcutaneously, every 12 hours, after the seventh dose. Anemia, hemorrhage, thrombocytopenia, and painful swelling at injection sites are complications of heparin administration in horses.

Animals↗
PubMedDate not supplied

Hyperlipemia in 9 miniature horses and miniature donkeys.

The medical records from 9 consecutive miniature horses (n = 5) and miniature donkeys (n = 4) with hyperlipemia (serum triglyceride concentration > 500 mg/dL) were reviewed. In all cases, hyperlipemia was a secondary complication of a primary systemic disease including septicemia, colitis, parasitism, esophageal obstruction, gastric impaction and rupture, fecalith, and pituitary adenoma. Therapy consisted of specific treatment for the primary disease, supportive care, and nutritional support. The mean time for resolution of hyperlipemia in cases requiring nutritional support (n = 6) was 7 days, and the duration of nutritional support in surviving patients was 11.7 days. Seven of 9 patients survived. The primary disease resulted in death in 2 patients. Enteral feeding with commercially prepared low residue diets and treatment of the primary disease was successful in reversing hyperlipemia in 5 of 6 surviving patients that required nutritional support. Parenteral administration of a glucose-based (non-lipid) solution was successful in resolving hyperlipemia in 1 patient.

Animals↗
PubMedDate not supplied

A portable blood gas analyzer for equine venous blood.

Evaluation of a portable blood gas analyzer, (StatPal II, Unifet, Inc, La Jolla, CA) was performed using tonometered solutions and equine blood. Samples were analyzed by the StatPal II and either an Instrument Laboratory IL1306 (Lexington, MA) or a Radiometer ABL50 blood gas analyzer (Radiometer America Inc., Westlake, OH). Comparison of the StatPal II and the IL1306 was done by analysis of 3 tonometered solutions (acidic, normal, and alkalotic) and 27 equine venous blood samples. Blood pH, PCO2, PO2, and [HCO3] values were altered by IV infusion of 5% sodium bicarbonate or exercising the horses on a treadmill. Comparison of the StatPal II and the Radiometer was performed by analysis of 78 blood samples collected from Standardbred horses before a race. Data were analyzed for the venous blood samples using a paired two-tailed Student's t test and Bland-Altman plots, with significance set at P < .05. The coefficients of variation for pH, Pco2, Po2, and [HCO3-] values of the tonometered solutions analyzed by the StatPal II ranged from 0.067% to 0.087%, 2% to 3.21%, 1.21% to 2.67%, and 0.267% to 0.828%, respectively. Comparison of the equine blood samples analyzed by the StatPal II and the IL1306 demonstrated statistically significant, but clinically irrelevant differences in pH, Pco2, and Po2, but not [HCO3-]. There were statistically significant, but clinically irrelevant differences between the StatPal II and the Radiometer for pH, Pco2, and [HCO3-], but not for Po2. It is concluded that the StatPal II provides reproducible and acceptable analysis of equine venous blood gas samples.

Animals↗
PubMedDate not supplied

Necrotizing enterocolitis in horses: a retrospective study.

The clinical and clinicopathologic characteristics of fatal necrotizing enterocolitis were examined in 16 horses (age 4 months to 12 years). At initial presentation, 8 of 16 horses were pyrexic (median temperature, 38.4 degrees C; range, 33.8 to 40.6 degrees C); all 16 were tachycardic (median heart rate, 93 bpm, range, 66 to 138 bpm); 13 of 16 were tachypneic (median heart rate, 36 bpm, range, 16 to 80 bpm), dehydrated, and had discolored mucous membranes. All horses that were pyrexic were also tachycardic and tachypneic. PCV was high (> 45%) in 14 horses. Six horses were leukopenic (< 5,000 cells/microL); 12 were neutropenic (< 2,300 cells/microL), and 14 had > 100 band neutrophils/microL. Twelve horses were acidemic (pH < 7.37; range, 6.88 to 7.33) and the venous bicarbonate concentration was low (< 23 mEq/L) in 14 horses. Median anion gap in 16 horses was 31.5 mEq/L (> 15 mEq/L in 15 horses). Eleven of 16 horses were hyponatremic (< 137 mEq/L), 1 horse was hypernatremic (> 143 mEq/L), 3 were hypokalemic (< 3.2 mEq/L), 6 were hyperkalemic (> 4.5 mEq/L), and 14 were hypochloremic (< 98 mEq/L). Serum creatinine concentrations were high (> 1.4 mg/dL) in 15 horses. Abdominal fluid was examined in 12 horses 4 had total protein concentrations > 2.5 g/dL and 6 had nucleated cell counts > 5,000/ microL and < 10,000/microL; none had > 10,000/microL. Eight of 12 samples revealed a nondegenerate neutrophilia (> 50%). Abdominal fluid collected from 4 horses immediately before death was normal in 2 horses and indicative of suppurative inflammation in 2. All 8 horses tested had low or nonexistent serum immunofluorescent antibody titers to Ehrlichia risticii. Four of 16 horses had Salmonella spp isolated from feces or tissues. All 16 horses either died (5 of 16; 31%) or were euthanized because of a grave prognosis. Median time to death was 45.5 hours (range, 7 to 113 hours) from the time of admission. Death was preceded by severe abdominal pain in 14 horses. Fatal necrotizing enterocolitis of horses is characterized by a brief course, profound dehydration, electrolyte derangements, acid-base abnormalities, and terminally, severe abdominal pain. Abdominal fluid analysis was frequently not indicative of the severity of disease.

Acid-Base Equilibrium↗
PubMedDate not supplied

Diagnostic validity of electroencephalography in equine intracranial disorders.

Electroencephalography (EEG) is a valuable diagnostic test to identify functional disturbances in brain activity. The purpose of this study was to assess the validity of EEG as a diagnostic indicator of intracranial diseases in horses. The validity of EEG was estimated by comparing clinical, clinicopathologic, and histopathologic findings to EEG findings in 20 horses examined for seizures. collapse, or abnormal behavior between 1984 and 1997. A bipolar left-to-right, back-to-front montage and a bipolar circular montage were recorded from sedated (4) and anesthetized (16) horses. Visual and semiquantitative masked analysis of EEG recording Ist was validated on 10 horses presented for problems other than intracranial diseases. EEG pattern was normal in 7 of the 20 clinically affected horses. Abnormal EEG patterns included high-voltage slow waves and discrete paroxysmal activity with or without generalized activity in 13 horses. Histopathologic diagnoses in 10 horses included meningoencephalitis, neuronal necrosis, congenital anomalies. cerebral edema. and abscess. All of these horses had abnormal EEG patterns (sensitivity, 100%) with a positive neuroanatomic correlation in 7 animals. Localization of histopathologic and EEG abnormalities did not correlate in 15% of the horses (3/20). The cause of neurologic signs could not be explained at postmortem examination in 10 animals and the EEG pattern was normal in 7 of these horses (specificity, 70%). In conclusion, equine EEG was a sensitive tool in the diagnosis of intracranial disorders.

Animals↗