Postprandial arterial vasodilation in the equine distal thoracic limb

The effects of feeding on blood flow to the equine foot are poorly understood. In a temperature-controlled room, duplex Doppler ultrasonographic observations were made pre- and postprandially of the lateral proper palmar digital artery of 5 horses, randomly assigned to twice and 4 times daily feeding in an unbalanced 2 period crossover design. Arterial diameter and blood velocity were measured over 4 h and additional observations made of heart rate, blood pressure, total plasma protein, packed cell volume, plasma glucose and insulin. There was no effect of the feeding regimen on any variable. Postprandially, there were significant increases in arterial diameter, blood velocity, total plasma protein, plasma glucose and insulin; the other variables were unchanged. It appeared that the normal postprandial response was an increase in blood flow to the foot. The value of ultrasonography for noninvasive investigation of the peripheral vasculature of the conscious horse was established; and in the future it may have a role in the diagnosis of vascular diseases of the foot.     

Diurnal variations in the plasma concentration of parathyroid hormone in dogs

The plasma concentrations of parathyroid hormone (PTH), ionised calcium (Ca(2+)), total calcium, albumin and inorganic phosphorus, and the pH were measured in blood samples obtained from nine dogs during a period of 26 hours. The plasma pth levels fluctuated slightly during the day, by about 20 pg/ml, but there was a distinct peak (42.8 [8.8] pg/ml) at 07.00. Plasma Ca(2+) showed a diurnal pattern in which two peaks (increases of 0.03 mmol/l) were observed at 05.00 and 17.00, and the plasma concentration of inorganic phosphorus showed a similar pattern. There were no diurnal changes in total calcium or albumin.     

Changes in haematology and plasma biochemistry during maximal exercise in greyhounds

The haematological and biochemical changes associated with racing over 235 and 420 metres were studied in 23 greyhounds. Blood samples were collected while the dogs were resting and immediately after and 30 minutes after racing. Significant increases in red blood cell count, haemoglobin concentration and haematocrit occurred. The increase in haematocrit was accompanied by increases in total plasma protein and creatinine concentrations. Blood lactate increased to 11.4 and 13.2 mmol/litre over 235 and 420 metres, respectively, and plasma glucose increased to 7.9 and 8.2 mmol/litre. After the 420 metres, the mean plasma ammonia concentration was 256 mumol/litre. Plasma free fatty acid concentrations also increased after dogs had run both distances. The highest concentrations of glycerol and uric acid were found 30 minutes after exercise.     

Responses to sprint exercise in the greyhound: effects on haematology, serum biochemistry and muscle metabolites

To investigate the haematological, biochemical and metabolic response of greyhounds to sprint exercise, five greyhound dogs with previously placed carotid arterial catheters were sprinted over a distance of 400 m, chasing a lure. The time to complete the 400 m ranged from 25 to 27 seconds. Before exercise and at intervals for up to one hour after exercise, arterial blood samples were collected for haematology, serum biochemistry, plasma lactate and arterial blood gas measurements. Muscle samples for metabolite measurements were collected by needle biopsy of the vastus lateralis muscle. Red cell indices were increased for up to 20 minutes after exercise and there was a transient leucocytosis and neutrophilia. Serum biochemical changes reflected some fluid movement from the vascular compartment, there being increases in osmolality and total protein. Other changes included significant increases over resting control values for serum glucose, creatinine and potassium. The tension of oxygen in arterial blood was increased after exercise, while that of carbon dioxide fell, and there was a decrease in arterial pH. These changes were no longer significant by 30 minutes after exercise. The mean rectal temperature increased to 41 degrees C after exercise and remained elevated up to and including the 30 minutes after exercise measurement. No changes were found in muscle ATP or glycogen from before to after exercise. However, concentrations of muscle glucose and glucose-6-phosphate were increased immediately after exercise. Muscle and plasma lactate concentrations showed a similar time course for disappearance and after peaking at 27 mmol litre-1, five minutes after exercise, the plasma lactate returned towards pre-exercise values by 30 minutes after exercise.     

Evaluation of oxidative stress markers for the early diagnosis of allograft rejection in feline renal allotransplant recipients with normal renal function

The purpose of this study was to identify oxidative damage to renal allografts during graft rejection by evaluating changes in oxidative markers and plasma lactate levels in feline renal allotransplant recipients. Heterotopic renal allotransplantations were performed between 8 adult feline cross-matched donors. Following 14 d of immunosuppression, the drugs were discontinued to allow allograft rejection. Baseline and serial postoperative evaluations of serum creatinine, plasma lactate, plasma thiobarbituate reactive substances (TBARS), plasma creatol, urine creatol, and renal sonographic cross-sectional area were performed. When sonographic evaluation revealed the absence of blood flow to the allograft, the rejected kidney was nephrectomized and evaluated histopathologically. Allograft rejection occurred in all cats by day 26. A significant elevation in body temperature occurred during the rejection period. No significant change was observed between any of the time periods for plasma TBARS, creatol, or urine creatol. There was a significant decrease in plasma lactate levels throughout the study. Markers of oxidative stress from venous blood did not reflect renal allograft rejection in cats with a normally functioning native kidney. Renal allograft rejection may be associated with significant increases in body temperature and warrants further investigation.     

Effects of high-intensity exercise on plasma catecholamines in the thoroughbred horse.

In Study 1, a single speed test of 6 to 12 m/sec was performed for 2 mins at an incline of 5 degrees on a high-speed treadmill (single-step test). Only one speed was performed per session and blood samples were taken before and after the test. In Study 2 horses cantered for 1 min at increasing speeds of 6 to 13 m/sec on an incline of 3 degrees (multiple-step test). Blood samples were taken before exercise, throughout the test and during recovery. In the single-step test plasma concentrations of adrenaline and noradrenaline both increased at speeds of 9 m/sec, as did blood lactate. Mean concentrations of adrenaline and noradrenaline at the end of the 12 m/sec test were 153 and 148 nmol/litre, respectively. Plasma concentrations were similar over all speeds although there was a tendency for the increase in noradrenaline to be greater than that of adrenaline at the lower speeds. The multiple-step test resulted in smaller increases in both adrenaline and noradrenaline. Although again closely correlated, increases in adrenaline were 20-30% greater than those for noradrenaline. In both exercise models, changes in plasma adrenaline and noradrenaline values with exercise showed an exponential relationship to plasma lactate. A plasma half-life of less than 30 secs was indicated during recovery from the multiple-step test. Changes in adrenaline and noradrenaline were much greater than previously recorded in man and emphasise the importance of catecholamines in mediating the physiological response of the horse to exercise.     

A comparison of the effects of electroimmobilisation and, or, shearing procedures on ovine plasma concentrations of beta-endorphin/beta-lipoprotein and cortisol

The effects of electroimmobilisation (EIM) and shearing procedures on the plasma concentrations of beta-endorphin/beta-lipotrophin (beta-EP/beta-LPH) and cortisol were compared in conscious sheep. Serial blood samples were collected from five groups of animals subjected to either EIM during simulated shearing (EIM + SS), SS, EIM, shearing or control procedures. EIM and shearing each caused significant increases in the plasma concentrations of beta-EP/beta-LPH and cortisol. The responses to EIM and shearing were significantly greater than in the control animals but were not significantly different from each other. There were no significant differences in the mean plasma concentrations of cortisol following treatment between EIM and EIM + SS groups or between SS and control groups. However, the plasma cortisol concentrations after treatment in the EIM + SS group were significantly greater than in the SS group.     

Preliminary investigation of alterations in blood viscosity, cellular composition, and electrophoresis plasma protein fraction profile after competitive racing activity in Thoroughbred horses

In this preliminary investigation, various hematologic variables potentially influential in determining the degree of blood viscosity were evaluated in 10 Thoroughbred horses subjected to competitive acute running exercise. Following completion of sprints over a distance of 1.25 miles, mean percent (+/- SD) increases in PCV (38.3 +/- 12.9%), RBC (47.8 +/- 15.3%), and rouleaux index (232.7 +/- 176.8%) were recognized. Simultaneous increases in total plasma protein (28.3 +/- 5.31%), serum albumin (26.7 +/- 6.80%), alpha 1-globulin (60.0 +/- 49.0%), alpha 2-globulin (25.5 +/- 27.9%), beta 1-globulin (46.7 +/- 21.1%), beta 2-globulin (35.0 +/- 50.6%), gamma 1- and 2-globulins (38.7 +/- 29.6%), and plasma fibrinogen (12.5 +/- 10.4%) concentrations increased simultaneously. Horses also had consistent decreases in albumin:globulin ratio (-10.0 +/- 7.43%). Alterations in these hematologic values after acute running exercise in Thoroughbred horses accompanied increases in serum (69.3 +/- 39.7%), plasma (39.7 +/- 11.9%), and blood (134.7 +/- 55.3%) viscosity.     

Relationship between the quality of dietary proteins and the functional status of the adrenal cortex. Variations in the content of transcortion, free corticosterone and total corticosterone in the blood plasma of rats fed with proteins of various quality]

Growing male Wistar rats were used to test in which way variations in the quality of dietary proteins (10% absorbable crude protein; casein supplemented with 4% methionine (K); casein/gelatine (1 : 3); maize gluten supplemented with 4 amino acids; and maize gluten) influenced the binding capacity of blood plasma for corticosterone, and the concentration of corticosteroid-binding globulin ("CBG"), total corticosterone, free corticosterone and albumin-bound corticosterone in blood plasma. The binding capacity of the blood plasma for corticosterone and the total concentration of corticosterone, CBG, free corticosterone and albumin-bound corticosterone were found to rise with the improving quality of the dietary proteins (r = 0.830). A close correlation was found to exist between the concentration of total corticosterone in the blood plasma and CBG. Increases in the total concentration of corticosterone in blood plasma are, in 84% of all cases, brought about by increases in CBG concentrations. In conclusion, reference is made to the significance which such results may have for the control of regulatory processes.     

Motility of the rumen and abomasum during hypocalcaemia.

The relationship between plasma calcium level and rumen motility in cows and sheep and abomasal motility in cows was investigated by inducing hypocalcaemia in seven cows and five sheep by the infusion of Na2 EDTA over a period of approximately two hours. Rates and amplitudes of rumen and abomasal contractions were markedly reduced by the reduction of plasma calcium level to approximately 50% of normal. There were significant positive linear relationships (P less than 0.05) between rate and amplitude of rumen contractions in both sheep and cows over a plasma calcium range of 1-3 mmol/L. There was also a significant linear relationship (P less than 0.05) between plasma calcium and abomasal rate of contraction over the same range in cows, but the relationship with amplitude of abomasal contraction was not quite significant (P less than 0.1 greater than 0.05).     

Comparison of whole blood and plasma potassium concentrations in dogs using the Reflovet system

Background: The Reflovet system is designed for chemical analysis of whole blood. However, plasma or serum is recommended for potassium analysis because of possible interference from RBC potassium. Because RBC potassium concentration is low in most canine erythrocytes, however, there should be little or no interference.
Objective: The objective of this study was to compare potassium results obtained in whole blood and in plasma from dogs using the Reflovet system.
Methods: Blood samples were collected from 104 dogs into lithium-heparin tubes. The potassium concentration was measured in whole blood, and subsequently the PCV was measured. Samples were centrifuged and the potassium concentration was measured in plasma. Comparisons were made using Deming's regression and Bland-Altman difference plots.
Results: There was very good correlation between results of potassium measurements in whole blood and plasma ( r = 0.93). Potassium values were moderately lower in whole blood: Potassium_blood= 0.912 × Potassium _plasma+ 0.119. Hemolysis had a negligible effect on the results, but the difference increased with the PCV value. In more than 90% of samples, the difference between the 2 measurements was ≤ 0.3 mmol/L.
Conclusion: There is only a negligible difference in most cases between potassium values in canine plasma and whole blood using the Reflovet system.     

ELECTROCARDIOGRAPHY AND HAEMATOLOGY OF HORSES COMPETING IN A THREE-DAY EVENT

The electrocardiograms of 22 horses competing in a 3-day event were recorded before and after the event. In addition, blood samples were taken for determination of packed cell volume and total plasma protein before, during and after the speed and endurance phases (Day 2).
The electrocardiograms of 13 horses showed various abnormalities before the event, most of which were T wave changes. As a result of competition in the event, there was a significant increase in the number of leads showing T wave abnormalities when the electrocardiograms taken before and after the event were compared. At all times measurements were taken there were significant increases in packed cell volume and total plasma protein over values obtained prior to the event.     

The effect of arginine vasotocin on blood volume, plasma protein and electrolyte concentrations in the cockerel, Gallus domesticus

The effect of arginine vasotocin (AVT), 0.1 μg/kg body weight, on blood volume, plasma protein and Na+ and K+ concentrations was investigated in New Hampshire cockerels. Significant increases in blood volume were observed 45 and 90 min following AVT. The plasma protein concentration decreased significantly after 4 h. The plasma Na⁺ concentration significantly increased while that of K+ decreased after 1 h. Significant changes in electrolyte concentrations were found up to 4 h following the AVT administration.     

Blood coagulation parameters in clinically normal intensively farmed red deer (Cervus elaphus) and fallow deer (Dama dama)

Reference ranges for five parameters of blood coagulation were established in clinically normal farmed fallow deer (Dama dama) and red deer (Cervus elaphus). Storage of plasma at -15 degrees C resulted in small increases in activated partial thromboplastin time (APTT) for both species, and in the one stage prothrombin time (OSPT) of fallow deer, between days 1 and 30. These times were then stable between days 30 and 60. The fibrinogen levels of fallow deer plasma showed a small apparent increase over 60 days. These storage artefacts were not of sufficient magnitude to preclude the use of such plasma for diagnostic purposes although they could limit its use in research. Levels of fibrin/fibrinogen degradation products (FDP) were not affected by storage at -15 degrees C. Rabbit brain thromboplastin appeared adequate for OSPT determination in both species. The activated clotting time (ACT) is recommended as a field test for screening the intrinsic and common pathways of blood coagulation in deer.     

Clinical signs and hematologic,cytokine, and plasma nitric oxide alterations in response to Strongylus vulgaris infection in helminth-na?ve ponies

The objective of this study was to determine the effect of infection with Strongylus vulgaris on serum cytokines and plasma nitric oxide (NO) concentrations in helminth-naive ponies. Group 1 (n = 21) was given 500 S. vulgaris L3 larvae and group 2 (n = 7) received a saline control. Ponies were monitored daily for clinical signs, and blood was collected for complete blood cell counts and serum cytokines (TNF, IL-1, IL-6) quantification. Group 1 ponies were depressed, anorexic, and febrile for variable periods of time. Plasma NO was increased on day 21 in group 1 and on days 9 and 21 in group 2. Significant increases in total white blood cell counts, fibrinogen, and plasma protein concentrations in group 1 were found. Significant decreases in red blood cell counts and packed cell volume were also noted in group 1. There were no differences in serum cytokines across time in either group of ponies. Despite the lack of proinflammatory cytokine induction with the apparent inflammatory response to S. vulgaris there is evidence of a potential role of NO.     

Effect of electroimmobilisation on ovine plasma concentrations of beta-endorphin/beta-lipotrophin, cortisol and prolactin

The effect of electroimmobilisation on the plasma concentrations of beta-endorphin/beta-lipotrophin (beta-EP/beta-LPH), cortisol and prolactin (PRL) has been assessed in sheep. Serial blood samples were collected from control and electroimmobilised animals during the first and fourth of a series of four repeated treatments over two days. After electroimmobilisation the mean (+/- SEM) plasma concentrations of beta-EP/beta-LPH increased significantly from 132 +/- 19 pg ml-1 to 545 +/- 111 pg ml-1; the plasma concentrations of cortisol also increased significantly from 22.3 +/- 3.5 ng ml-1 to 108.0 +/- 12.9 ng ml-1. There was no significant change in plasma PRL concentrations after electroimmobilisation and also no significant difference between the plasma concentrations of PRL in the control and electroimmobilised animals. There was no significant difference between the effects of the first and fourth exposure to electroimmobilisation on the plasma concentrations of beta-EP/beta-LPH, cortisol and PRL. These results suggest that the endocrine response to electroimmobilisation may be specific to the pituitary-adrenal axis.     

Testosterone concentration in the seminal plasma of cocks

Testosterone concentrations in the seminal plasma of cocks ranged from 0.46 to 5.05 ng/ml and were substantially lower than in blood plasma. No significant variation was noted in seminal plasma testosterone concentrations during the light phase of the day, whereas the concentration in blood declined over this period. Spermatozoal concentration and seminal testosterone decreased in the third sample of the semen collected sequentially at 3 h intervals. Testosterone concentrations in seminal plasma (1.57 +/- 0.17 ng/ml) and in the semen from the ductus deferens (1.34 +/- 0.24 ng/ml) were not significantly different.     

A study on the effects of the rapid intravenous infusion of hypertonic Na and K solutions into normal conscious sheep on some cardiac characteristics and blood analytes.

Five normal, conscious, aged Merino ewes were infused with 200 ml of an aqueous solution containing 5% NaCl and 0.25% KCl (HNaK) at a mean rate of 0.024 ml/kg/s and four similar sheep with 0.9% saline at a mean rate of 0.018 ml/kg/s. Five ECG tracings were obtained over a 6-h period--two (20 s each) before, one (continuous tracing) during the infusion, and two (20 s each) afterwards. The heart was auscultated during the infusion. Seven heparinized blood samples were obtained--three before the infusion (1.5 h, 1.0 h, and immediately before), and four afterwards (immediately, 2.5 h, 4.5 h, and 24 h after). Determinations were made of changes in mean PCV, red cell counts, mean corpuscular volumes, plasma Na, K, Ca and Mg, and of erythrocyte Na and K concentrations. Analysis of variance revealed increases in heart rate when the results from both groups were combined, but no significant effects on cardiac rhythm. Auscultation revealed marked fluctuations in cardiac intensity within individual sheep and marked differences between sheep, particularly in those infused with HNaK. In the HNaK group there were significant increases in erythrocyte and plasma Na, and erythrocyte K and decreases in plasma Ca during the infusion. Plasma K increased from the termination of the infusion to 2.5 h afterwards in the saline group but decreased unexpectedly during the same period in the group infused with HNaK [corrected].     

Cardiovascular and pharmacokinetic effects of isoxsuprine in the horse

Isoxsuprine (0.6 mg/kg) administered IV to 6 standing horses produced substantial, transient decreases in systemic blood pressure, systemic vascular resistance, and stroke volume. It also produced substantial, transient increases in heart rate, cardiac output, and purposeful movement. Plasma concentrations of isoxsuprine peaked soon after the drug was administered IV and then decreased over a 12-hour period in a biexponential manner, with distribution and elimination half-lives of 14 minutes and 2.67 hours, respectively. Total body clearance and steady-state volume of distribution were calculated to be 53.8 ml/min/kg and 10.5 L/kg, respectively. When a recommended therapeutic dosage regimen (0.6 mg/kg 2 times a day, per os) was used in 4 of these horses, changes were not detected. Isoxsuprine was not detected in plasma after the drug was given orally. We conclude that 0.6 mg of isoxsuprine/kg given orally every 12 hours is not likely to produce cardiovascular changes in the resting horse and that this is probably because plasma concentrations are not high enough to do so.     

Effects of dietary boron supplementation on some biochemical parameters, peripheral blood lymphocytes, splenic plasma cells and bone characteristics of broiler chicks given diets with adequate or inadequate cholecalciferol (vitamin D3) content

(1) The effects of 5 and 25 mg/kg boron supplementation of diets with inadequate (6.25 microg/kg) or adequate (50 microg/kg) cholecalciferol (vitamin D3) content on some biochemical parameters, tibia characteristics, peripheral blood lymphocyte and splenic plasma cell counts of broilers were investigated. (2) Supplementation of the diet with boron affected plasma concentrations of boron, iron, copper and zinc and also tibia boron, zinc and calcium concentrations but did not have any effect on tibia iron or copper concentrations or tibia ash and tibia weight values. (3) Boron supplementation caused significant increases in splenic plasma cell count but decreased the proximal and distal tibia growth plate widths. There was no effect of boron supplementation on peripheral blood alpha-naphthyl acetate esterase (ANAE) content. Whole blood haematocrit and haemoglobin counts were significantly increased by boron supplementation but there were no effects on leucocyte ratios such as eosinophil, basophil, monocyte, lymphocyte and thrombocyte. (4) In general, the findings of the present study support the hypothesis that boron has an important biological role that affects the mineral metabolism of animals by influencing both biochemical and haematological mechanisms.