Introduction: The aim of this study was to evaluate the effect of lipoprotein fraction isolated from ostrich egg yolk (LPFo) on the metabolic activity of boar spermatozoa following liquid semen storage in different extenders and temperatures. Material and Methods: Boar ejaculates were extended in Androhep, Beltsville thawing solution (BTS), and Martín-Rillo and Alias (MR-A) without (control) or with the addition of LPFo and stored for three days at either 5°C or 16°C. The analysed sperm parameters included total motility (TMOT), plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), oxygen consumption, and adenosine triphosphate (ATP) production. Results: The sperm metabolic activity seemed to be higher in the LPFo-based extenders following storage for three days, irrespective of the storage temperature. Compared with the LPFo-free extenders, significantly higher (P < 0.05) sperm PMI and MMP were observed in BTS and MR-A extenders supplemented with LPFo during storage for three days at 5°C. Spermatozoa stored in the BTS-LPFo extender exhibited higher (P < 0.05) TMOT and oxygen consumption, whereas higher (P < 0.05) PMI was observed in spermatozoa stored in Androhep-LPFo and MR-A-LPFo for three days at 16°C. No significant differences (P > 0.05) in ATP content were observed between the LPFo-free and LPFo-based extenders during storage. Conclusions: Supplementation of LPFo to semen extenders had varying effects on the metabolic activity of boar spermatozoa stored at different temperatures. It can be suggested that the interactions of various components of the extenders and seminal plasma with LPFo exert beneficial effects on the sperm metabolic activity during liquid storage of boar semen.

The cardiopulmonary effects of thiopental sodium were studied in hypovolemic dogs from completion of until 1 hour after administration of the drug. Hypovolemia was induced by withdrawal of blood from dogs until mean arterial pressure of 60 mm of Hg was achieved. After stabilization at this pressure for 1 hour, 8 mg of thiopental/kg of body weight was administered IV to 7 dogs, and cardiopulmonary effects were measured. After blood withdrawal and prior to thiopental administration, heart rate and oxygen utilization ratio increased, whereas mean arterial pressure, mean pulmonary arterial pressure, central venous pressure, pulmonary wedge pressure, cardiac index, oxygen delivery, mixed venous oxygen tension, and mixed venous oxygen content decreased from baseline. Three minutes after thiopental administration, heart rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary vascular resistance, and mixed venous oxygen tension increased, whereas oxygen utilization ratio and arterial and mixed venous pH decreased from values measured prior to thiopental administration. Fifteen minutes after thiopental administration, heart rate was still increased; however by 60 minutes after thiopental administration, all measurements had returned to values similar to those obtained prior to thiopental administration.

To assess the suitability of sheep for exercise studies, the effect of incremental exercise and conditioning on oxygen consumption was studied. Six sheep were adapted to a treadmill and subsequently trained 8 weeks. The sheep were then studied, in random order, using 3 incremental exercise protocols (EX-1, EX-2, and EX-3). The protocols were chosen to approximate high (EX-1), moderate (EX-2), and low (EX-3) intensity exercise by varying treadmill speed and incline. The sheep were then conditioned for an additional 12 weeks and retested on the EX-2 protocol. During exercise, oxygen consumption, gas exchange ratio (R), and rectal temperatures (Tb) were recorded. All 3 protocols resulted in significant increases in oxygen consumption, R, and Tb (P < 0.05). Maximum oxygen consumption for EX-1, 49.9 +/- 5.0 ml/min/kg of body weight, was significantly greater than maximum oxygen consumption for EX-2 and EX-3, 37.8 +/- 6.5 and 42.3 +/- 6.0 ml/min/kg, respectively (P < 0.05), whereas maximum R and maximum Tb were similar. After the additional 12-week conditioning, time on the treadmill increased 40% from 9.58 +/- 0.87 to 13.4 +/- 0.44 minutes, and maximum oxygen consumption increased 27% to 48.1 +/- 9.1 ml/min/kg. These data indicated that maximum oxygen consumption varied with intensity of the exercise, 12 weeks of maximal exercise conditioning was sufficient to produce a measurable training effect (ie, increase endurance and maximum oxygen consumption) and sheep are suitable for maximal exercise studies where oxygen consumption measurements are desired.

Using isolated autoperfused intestinal segments, the effects of flunixin meglumine administration on systemic arterial blood pressure, jejunal blood flow, vascular resistance, motility, arteriovenous oxygen difference, and oxygen consumption were determined in 10 anesthetized ponies ventilated with a mixture of halothane and oxygen. Saline solution or flunixin meglumine (1.1 mg/kg of body weight) was infused as a single bolus into the left jugular vein. By 10 minutes, flunixin meglumine increased systemic aterial blood pressure and increased intestinal vascular resistance. The jejunal blood flow, however, was not significantly decreased until 1 hour after flunixin meglumine administration. Intestinal motility, arteriovenous oxygen difference, and oxygen consumption were unchanged. Results indicated that acute administration of flunixin meglumine increases systemic arterial pressure and intestinal vascular resistance, but the resulting intestinal vasoconstriction does not lead to compromise of intestinal viability.

Cardiopulmonary and behavioral responses to detomidine, a potent alpha 2-adrenergic agonist, were determined at 4 plasma concentrations in standing horses. After instrumentation and baseline measurements in 7 horses (mean +/- SD for age and body weight, 6 +/- 2 years, and 531 +/- 48.5 kg, respectively), detomidine was infused to maintain 4 plasma concentrations: 2.1 +/- 0.5 (infusion 1), 7.2 +/- 3.5 (infusion 2), 19.1 +/- 5.1 (infusion 3), and 42.9 +/- 10 (infusion 4) ng/ml, by use of a computer-controlled infusion system. Detomidine caused concentration-dependent sedation and somnolence. These effects were profound during infusions 3 and 4, in which marked head ptosis developed and all horses leaned heavily on the bars of the restraining stocks. Heart rate and cardiac index decreased from baseline measurements (42 +/- 7 beats/min, 65 +/- 11 ml.kg of body weight-1.min-1) in linear relationship with the logarithm of plasma detomidine concentration (ie, heart rate = -4.7 [log(e) detomidine concentration] + 44.3, P < 0.01; cardiac index = -10.5 [log(e) detomidine concentration] + 73.6, P < 0.01). Second-degree atrioventricular block developed in 5 of 7 horses during infusion 3, and in 6 of 7 horses during infusion 4. Mean arterial blood pressure increased significantly from 118 +/- 11 mm of Hg at baseline to 146 +/- 27 mm of Hg at infusion 4. Similar responses were observed for mean pulmonary artery and right atrial pressures. Systemic vascular resistance (baseline, 182 +/- 28 mm of Hg.ml-1.min-1.kg-1) increased significantly during infusions 3 and 4 (to 294 +/- 79 and 380 +/- 58, respectively). Plasma atrial natriuretic peptide concentration was significantly increased with increasing detomidine concentration (20.4 +/- 3.8 pg/ml at baseline to 33.5 +/- 9.1 at infusion 4). There were few significant changes in respiration rate and arterial blood gas and pH values. We conclude that maintenance of steady-state detomidine plasma concentrations resulted in cardiopulmonary changes that were quantitatively similar to those induced by detomidine bolus administration in horses.

On the basis of results in dogs, conditioning exercise may increase sensitivity to nondepolarizing muscle relaxants. Five Thoroughbreds were exercised/conditioned 3 times weekly on a treadmill for 8 months. Increasing maximal rate of O2 consumption verified that the horses were responding to exercise conditioning. Six nonexercised Thoroughbreds served as the control group. Studies were done with horses under general anesthesia by use of halothane during partial paralysis by a brief constant-rate infusion with the muscle relaxant, metocurine iodide. Quantification of degree of paralysis of the hoof twitch (eg, digital extensor) occurred with simultaneous quantification of blood values of metocurine. Pharmacokinetic and pharmacodynamic analyses of the data were done by a nonlinear regression program, using the Hill equation. There were no differences in findings between exercised and nonexercised horses. The mean blood concentration for the 50% paralyzing dose of metocurine was 0.44 +/- 0.11 (SD) micrograms/ml in exercised horses, and 0.58 +/- 0.22 micrograms/ml in nonexercised horses. Despite evidence for a response to conditioning, a significant change in the sensitivity of the neuromuscular junction to metocurine was not found.

The effects of butorphanol tartrate on arterial pressure, jejunal blood flow, vascular resistance, oxygen extraction, and oxygen uptake were determined in 10 anesthetized ponies ventilated with a mixture of halothane and 100% oxygen, using isolated autoperfused jejunal segments. Physiologic saline solution or butorphanol tartrate (0.2 mg/kg of body weight) was administered as a single bolus into the left jugular vein. By 2 minutes, butorphanol decreased arterial blood pressure and intestinal blood flow, and increased intestinal oxygen extraction. However, intestinal vascular resistance and oxygen uptake were unaffected. Results of this study indicate that butorphanol tartrate induces a hypotension that secondarily decreases intestinal blood flow, but intestinal vascular resistance and metabolism are not adversely affected. We conclude that butorphanol tartrate does not compromise intestinal viability in halothane-anesthetized ponies and, therefore, may be a good analgesic choice for the equid destined for abdominal surgery.

The influence of distention (high baseline intraluminal pressure) and neostigmine methylsulfate on intestinal vascular resistance, oxygen uptake, and intraluminal pressure changes (rhythmic contractions) was studied in terminal jejunal segments which were perfused at a constant rate, in 16 anesthetized ponies. When baseline intraluminal pressure was increased to 10 mm of Hg, the intestinal vascular resistance and amplitude of rhythmic contractions were increased. Neostigmine induced cyclic increases in amplitude of rhythmic contractions whether intraluminal pressure was 0 or 10 mm of Hg. Neostigmine also increased intestinal oxygen uptake at intraluminal pressures of 0 mm of Hg, but not at 10 mm of Hg, and vascular resistance was not altered at either intraluminal pressure. The results indicate that intestinal hemodynamics are adversely affected by distention. Further, neostigmine did not adversely affect intestinal hemodynamics while increasing rhythmic contractions, suggesting that neostigmine may be useful in the treatment of ileus in equids.