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Biomedical subjects

P D Constable

Publications and source records attributed to P D Constable.

79 records · Page 5Linked to original sources
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Colonic luminal pressure in horses with strangulating and nonstrangulating obstruction of the large colon.

Colonic luminal pressure (median, range) measured during ventral midline celiotomy in 69 horses with strangulating obstruction (SO) of the large colon (SO; > or = 270 degrees large colon volvulus; 27 cm H2O: 2 to 80 cm H2O) was greater (P = .0023) than that measured in 37 horses with nonstrangulating obstruction (NSO) of the large colon (NSO; < or = 180 degrees volvulus or a nonstrangulating displacement; 18 cm H2O; 6 to 46 cm H2O). Sixty-five percent (45 of 69) of horses with SO and all horses with NSO survived. Survival analysis was restricted to 59 horses with large-colon SO that survived to hospital discharge or met the criteria specified for classification as nonsurvivors. Colonic luminal pressure in nonsurvivors (48.5 cm H2O; 34 to 80 cm H2O) was higher (P =.0001) than that measured in survivors (18 cm H2O; 2 to 50 cm H2O) of SO. From response operating characteristic curves, a luminal pressure of 38 cm H2O optimized the distribution of horses with SO into survivor and nonsurvivor groups. Sensitivity, specificity, and positive and negative predictive values for a colonic luminal pressure greater than 38 cm H2O in predicting nonsurvival were 0.89, 0.91, 0.72 and 0.97, respectively. Measurement of colonic luminal pressure may be useful for predicting survival in horses with colonic volvulus.

Animals↗
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Hyperlipemia and ketonuria in an alpaca and a llama.

An alpaca and a llama in late stages of gestation were evaluated for lethargy, anorexia, and recumbency. Both camelids had cloudy, white, turbid serum, elevated serum triglyceride (1564, 5658 mg/dL, respectively) and cholesterol (158, 297 mg/dL, respectively) concentrations, and ketonuria. Signs of fetal stress were evident ultrasonographically in the alpaca, and a live cria was delivered by Cesarean section performed under general anesthesia. The alpaca developed severe metabolic acidosis, hepatic lipidosis, and acute renal failure secondary to renal lipidosis and died 36 hours after admission despite medical therapy. Histopathology revealed renal and hepatic lipidosis and neutrophilic pancreatitis. The cria died 72 hours after birth. The llama responded to IV electrolyte, dextrose, and regular crystalline insulin therapy. The pregnancy was maintained, and the llama was discharged from the hospital 20 days after admission. Two months after discharge, the llama gave birth to a live, 5 kg cria. Findings of hypertriglyceridemia, hypercholesterolemia, elevated sorbitol dehydrogenase activity, metabolic acidosis, azotemia, and ketonuria occurred in these two camelids. Based on this report, camelids appear to be similar to both horses and cattle in their response to severe energy imbalances in late gestation.

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PubMedDate not supplied

Clinical and immunohistochemical characterization of thymic lymphosarcoma in a heifer.

A 2-year-old Holstein heifer with a swollen brisket, jugular vein distention, muffled heart sounds, tachycardia, and free gas bloat was examined. Thymic lymphosarcoma was suspected based on a negative agar gel immunodiffusion test for bovine leukemia virus, presence of atypical lymphocytes in pleural fluid, and detection of a mass in the thoracic inlet. Right-sided cardiac catheterization was performed, and markedly increased jugular venous pressures (41 mm Hg) with a pressure gradient of 29 mm Hg immediately cranial to the heart indicated constriction of the cranial vena cava. Immunohistochemical staining of formalin fixed, paraffin-embedded tissue sections of the tumor using a rabbit antihuman T cell, CD3 polyclonal antibody confirmed that the neoplastic lymphocytes were of thymic origin.

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Hemodynamic effects of calcium gluconate administered to conscious horses.

Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentration throughout the study. We conclude that calcium gluconate can safely be administered to conscious horses at 0.1 to 0.4 mg/kg/min and that administration will result in improved cardiac function.

Animals↗
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Determinants and utility of the anion gap in predicting hyperlactatemia in cattle.

The objectives of this study were to investigate the determinants of the anion gap (AG) in cattle and to evaluate the utility of AG in detecting hyperlactatemia in sick neonatal calves and adult cattle. The AG was calculated as AG = ([Na+] + [K+])-([Cl-] + [HCO-3]), with all values in mEq/L. The AG of healthy neonatal calves (n = 16) was 29.6 +/- 6.2 mEq/L (mean +/- SD), and the blood L-lactate concentration ranged from 0.5 to 1.2 mM/L. The AG was significantly (P < .05) correlated with serum phosphate (r = .66) and creatinine (r = .51) concentrations. The AG of neonatal calves with experimentally induced diarrhea (n = 16) was 28.6 +/- 5.6 mEq/L, and the blood L-lactate concentration ranged from 1.1 to 2.9 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .67), serum phosphate concentration (r = .63), creatinine concentration (r = .76), and blood pH (r = -.61). The AG of adult cattle with abomasal volvulus (n = 41) was 20.5 +/- 7.8 mEq/L, and the blood L-lactate concentration ranged from 0.6 to 15.6 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .60), serum phosphate concentration (r = .71), creatinine concentration (r = .65), albumin concentration (r = .47), total protein concentration (r = .54), blood pyruvate concentration (r = .67), and blood pH (r = -.41) but not plasma beta-OH butyrate concentration. The results indicate that the AG in cattle is only moderately correlated with blood L-lactate concentration and is similarly correlated with serum phosphate and creatinine concentrations in neonatal calves and adult cattle, as well as with serum albumin and total protein concentrations in adult cattle. Anion gap determination is of limited usefulness in predicting blood L-lactate concentration in sick cattle, whereas the correlation between AG and serum creatinine concentration in sick cattle suggests that an increased AG should alert the clinician to the potential presence of uremic anions.

Abomasum↗
PubMedDate not supplied

Ability of hematologic and serum biochemical variables to differentiate gram-negative and gram-positive mastitis in dairy cows.

Medical records of 142 dairy cows with clinical mastitis were examined to determine whether hematologic or serum biochemical results could be used to distinguish between mastitis episodes caused by gram-negative bacteria (n = 78) from those caused by gram-positive bacteria (n = 64). Signalment, historic information, hematologic and serum biochemical results, milk culture results, and outcome (discharged from hospital or died) were obtained from the medical records. Cows with gram-negative mastitis had significantly (P < .01) lower blood leukocyte, segmented neutrophil, monocyte, and lymphocyte counts and had higher blood hemoglobin concentrations and hematocrits than did cows with gram-positive mastitis. Serum urea nitrogen was the only serum biochemical result associated with pathogen type, and it was higher in cows with gram-negative mastitis than in those with gram-positive mastitis. Mortality rate (25% overall) did not differ between groups. Logistic regression indicated that routine hematologic analysis (segmented neutrophil count, monocyte count, and hemoglobin concentration) was an accurate predictor of gram-negative mastitis, with a sensitivity of .93, a specificity of .89, and an overall accuracy of 91%. The values for sensitivity and specificity were higher than those previously reported for clinical tests differentiating mastitis episodes caused by gram-negative bacteria from those caused by gram-positive bacteria. Our results indicate that routine hematologic analysis is useful for predicting pathogen type in dairy cows with clinical mastitis, thereby facilitating treatment decisions.

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