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Topic:Plasma
Plasma is the liquid component of blood in horses, consisting primarily of water, electrolytes, proteins, and waste products. It serves as a transport medium for nutrients, hormones, and waste products throughout the body. Plasma also plays a role in maintaining blood pressure and volume, as well as serving as a reservoir for critical proteins involved in clotting and immune responses. Research on equine plasma often focuses on its composition, functions, and applications in veterinary medicine, such as transfusions and diagnostic testing. This page compiles peer-reviewed research studies and scholarly articles that explore the properties, functions, and clinical applications of plasma in equine health.
Plasma biochemistry in the horse during 3-day event competition. Blood samples were collected from 16 Thoroughbred horses before, during and after the second day of a 3-day event. Plasma osmolality, concentrations of sodium, potassium, chloride, urea, creatinine, glucose, bilirubin, iron, total protein, albumin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, creatine kinase, calcium, inorganic phosphate, uric acid, cholesterol, triglycerides and non-esterified fatty acids were measured. Significant differences from pre-event values were found in all parameters with the greatest changes being found after the cross-country phase. ...
Plasma concentration of iditol dehydrogenase (sorbitol dehydrogenase) in ponies treated with aflatoxin B1. Twelve clinically normal Shetland ponies were allocated to one of four treatment groups. Aflatoxin B1 was administered at the dosage level of 2 mg/kg of body weight to group A, 1 mg/kg to group B, and 0.5 mg/kg to group C; a placebo was given to group D (controls). Plasma samples were assayed at 4-hour intervals for iditol dehydrogenase (ID) (sorbitol dehydrogenase) concentrations as an indicator of hepatic damage. One of the ponies in group A died 68 hours after dosing; another pony in group A died 76 hours after dosing. All other animals survived the experiment. The means of peak ID values w...
A freeze-thaw method for concentrating plasma and serum for treatment of hypogammaglobulinaemia. Components of plasma or serum, including immunoglobulins, were concentrated two-fold by freezing then collecting 40-50% of the initial volume during thawing. This concentrated plasma (or serum) was administered intravenously to treat hypogammaglobulinaemic foals and calves. An adaptation of this method suitable for field use is described.
Renin, aldosterone and cortisol in the thoroughbred horse. To assess the renin-aldosterone system in a large mammal, simultaneous morning activities of plasma renin and concentrations of aldosterone and cortisol were measured in 25 thoroughbred horses. Renin was relatively low in all horses (0.16 +/- 0.02 (S.E.M.) ng angiotensin I/ml per h), levels of aldosterone in plasma were 527 +/- 130 pmol/1 and levels of cortisol in plasma were 141 +/- 11 nmol/l. Levels of aldosterone were significantly correlated with levels of renin in all horses (r = 0.62, P less than 0.001) but not with those of cortisol, and renin was negatively correlated with age in male ...
Serum quality: an analysis of its components. Foetal and new born bovine sera, horse serum, human serum and human plasma, and protein solutions prepared from the by-products of human plasma fractionation have been analysed. Foetal bovine sera were found to have lower total protein (g/l) and % of gamma-globulin than the other sera studied while the potassium (mmol/1) was higher. Protease inhibitors could be detected in all specimens tested.
Protease inhibitor system in horses: classification and detection of a new allele. A method of horizontal thin layer polyacrylamide gel electrophoresis at acid pH has been developed for the separation of the prealbumins in equine plasma. Using this method, it has been possible to split the S allele into two, S1 and S2, bringing the total number of prealbumin alleles in Thoroughbred horses to eight. The gene frequencies of these eight alleles in Australian Thoroughbreds are presented. All eight prealbumin types exhibit antiprotease activity and therefore, it is suggested that the name prealbumin (Pr) should be abandoned in favour of protease inhibitor (Pi) although at this st...
Direct measurement of biliary bilirubin excretion in ponies during fasting. Biliary excretion of bilirubin, including the conjugate composition, was studied during feeding and during a 2.5-day fast of three pony mares with chronic external biliary (T-tube) fistulas. Fasting bilirubin excretion (1.96 +/- 0.74 microgram/min/kg of body weight), after establishing a new steady state, was not different from excretion during feeding (1.99 +/- 0.45 microgram/min/kg). Hyperbilirubinemia of fasting resulted from a reduced removal of plasma bilirubin rather than from an increased input of bilirubin into the plasma. Relative plasma excretion of the individual conjugate fractions...
Plasma and sweat electrolyte concentrations in the horse during long distance exercise. Blood samples were taken from 20 horses competing in a 100 km endurance ride and plasma concentrations of sodium, potassium, chloride, bicarbonate and protein measured. Measurements were performed on samples taken before the ride (pre-ride), at the mid point and end of the ride and after a 30 min recovery period (post-ride). Sweat samples were collected from 6 horses competing in the endurance ride and 14 horses competing in a 3-day event competition and sweat concentrations of sodium, potassium and chloride measured. There were substantial decreases in plasma electrolyte concentrations, which...
Pathophysiological changes associated with Parascaris equorum infection in the foal. The mechanisms involved in the pathophysiological disturbances associated with the presence of mature Parascaris equorum in the small intestine were investigated with radioisotopic techniques. The results suggested that, compared with worm-free controls, infected foals had a reduction in gut motility, an increase in the body solids ratio, a lowering of the body pool of albumin and a decreased ability to incorporate dietary methionine into plasma protein.
Metabolic and physiological effects of adrenoceptor agonists and antagonists in the horse. In the horse the effect of the adrenergenic agonists adrenaline, phenylephrine and salbutamol on haematocrit, plasma free fatty acid, glycerol and lactate levels were investigated. Effects on heart rate, sweating and muscle tremor were also studied. The effects of administration of the adrenoceptor antagonists propranolol, metoprolol, H35/25 and acepromazine on adrenaline-induced changes were examined. The results obtained with these agonists and antagonists suggest that the lipolysis and hyperglycaemia are mediated via beta-adrenoceptors. It appears that both beta1 and beta2 subtypes are invo...
Tissue and plasma activity of lactic dehydrogenase and creatine kinase in the horse. Lactic dehydrogenase, although widely distributed in most tissues, was more highly concentrated in skeletal muscle, cardiac muscle, kidney and liver. Isoenzyme patterns showed a selective concentration of LDH5 in skeletal muscle while in the heart LDH 1 and 2 were predominant. In contrast, creatine kinase was only present in substantial concentration in skeletal and cardiac muscle. The serum concentrationof both enzymes showed a wide range of activity.
Colic in the horse. A clinical and clinical chemical study of 42 cases. 42 horses were examined. The physical signs with relation to circulatory insufficiency and the abdominal disease were registered following a two-phased examination procedure. Great prognostic value was found in the degree of circulatory insufficiency judged by pulse rate and character, filling of the jugular vein, skin temperature, colour of mucous membranes, capillary refill time, sweating, depression, skin turgor and degree of enophthalmus. In making a causal diagnosis the abdomen was examined for shape, tenderness, peristaltic sounds, gastric dilation by siphoning, abnormal rectal findings ...
Occurrence of Leu-Lys-bradykinin and histidine-rich peptide in high-molecular-weight kininogen isolated from horse plasma. On incubation of purified horse plasma high-molecular-weight kininogen with purified plasma kallikrein, three new peptides, named fragment 1.2, fragment 1 and fragment 2, were released, in addition to the vasopeptide, bradykinin. Fragment 2 contained an extremely high level of histidine, in which eleven residues out of the total 48 residues were characterized. Thus the result proves the existence of the histidine-rich region in horse high-molecular-weight kininogen, which is similar to the region previously identified in bovine high-molecular-weight kininogen. Moreover, we have identified a ne...
Phenylbutazone toxicity in ponies. The oral administration of phenylbutazone at a dose rate of approximately 10 mg per kg per day for seven to 14 days resulted in the development of signs of toxicity in seven of eight ponies treated. Clinical signs included anorexia, depression and abdominal oedema. Blood biochemical determinations showed a decrease in total plasma protein and calcium concentrations with an increase in urea concentration. These changes were considered indicative of water retention. Three of the ponies died during treatment following the development of shock. Shock was considered to arise from the submucosal oed...
Pharmacokinetics of ketamine in the horse. Ketamine HCl was administered IV to xylazine HCl-treated horses. The plasma concentration of ketamine was measured several times after administration of the drug and these data were used to develop a two-compartment pharmacokinetic model. The distribution and the elimination phase half-lives averaged 2.9 and 42 minutes. The volume of the central compartment averaged 212 ml/kg of body weight and the volume of the peripheral compartment was approximately threefold larger. The total body clearance of ketamine averaged 26.6 ml/minute/kg. Plasma protein binding of ketamine averaged 50% over the con...
Effect of exercise, phenylbutazone, and furosemide on the plasma renin activity and angiotensin I in horses. Circulating concentrations of angiotensin I and plasma renin activity (PRA) were determined in 45 Thoroughbreds before prerace medication (at rest), 1 to 1 1/2 hours before racing but after prerace medication (prerace), within 15 minutes after racing (immediately postrace), and between 1 to 2 hours after racing. Angiotensin I was measured by radioimmunoassay, and PRA was determined by the rate of generation of angiotensin I in plasma incubated at 37 C. Irrespective of prerace medication, there was a marked increase in angiotensin I (0.478 +/- 0.034 to 0.848 +/- 0.051 ng/ml) and PRA (0.191 +/- ...
Physiologic alterations in the horse produced by food and water deprivation during periods of high environmental temperatures. Eight normal horses were held without access to food or water for 72 hours during a period of high environmental temperatures. During this period, the horses had an average weight loss of 51.6 kg (10.7% of body weight). Highly significant (P less than 0.001) decreases in extracellular fluid volume (18.6 L) and plasma volume (5 L) were observed during this period as compared with base-line values. Plasma protein, sodium, chloride, and osmolality progressively increased in response to the dehydration, whereas packed cell volume, plasma potassium, calcium, magnesium, and phosphate were not signif...
Electrocardiography, heart scope and haematology of horses competing in an endurance ride. Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnorma...
Adrenal gland function in the horse: effects of cosyntropin (synthetic) and corticotropin (natural) stimulation. The plasma concentration of hydrocortisone was determined in mares given either cosyntropin (100 IU, given IV) or corticotropin (200 IU, given IM). Plasma hydrocortisone concentrations of the mares treated with cosyntropin increased by 46%, 57% and 80% at 30, 60, and 120 minutes, respectively, when compared with base-line values; these values returned to base line at 240 minutes. In mares treated with corticotropin, mean plasma hydrocortisone concentrations increased by 42%, 143%, 101% and 155% at 30, 60, 120, and 240 minutes, respectively, when compared with base-line values. Differences in t...
Electrocardiography, Heart Score, and Hematology of Horses Competing in an Endurance Ride. Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid-ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnorma...
Comparative serologic study of equine piroplasmosis, with card and complement-fixation tests. An agglutinating antigen and a rapid card test (CT) for equine piroplasmosis was developed. The antigen for the CT was prepared from lyophilized Babesia caballi complement-fixation (CF) antigen. Serum and plasma samples for testing were obtained from known B caballi-infected horses and clinically normal horses maintained at the laboratory. Serum samples also were obtained from horses outside the continental United States, in areas where piroplasmosis is endemic. Comparative CT and CF tests were done on all samples. The CT correctly identified 85% of 192 plasma samples from known infected and n...
A case of pituitary adrenocorticotropin-dependent Cushing’s syndrome in the horse. In the horse, a syndrome of hirsutism, hyperglycemia, glucosuria, polydipsia, polyuria, polyphagia, and progressive debilitation has been recognized. Most often the syndrome has been associated with adenomas of the pars intermedia of the pituitary and bilateral adrenal hyperplasia or nodular hyperplasia involving primarily the zona fasciculata. Previously, the syndrome has been ascribed to compression of the hypothalamus by an expanding but functionally inactive pituitary neoplasm. In the present case, with RIA determination of plasma ACTH concentrations, the syndrome was ascribed to pituitary...
The effect of exogenous oxytocin on luteal function in mares. Daily injections of 150 units oxytocin administered to 6 mares on Days 4, 5, 6, 7 and 8 after ovulation (Day 0 = ovulation) failed to induced luteolysis as indicated by the maintenance of normal plasma progestagen concentrations and the occurrence of normal ovulatory intervals. Three additional mares were given oestrogen injections 24 h before an injection of oxytocin on Day 7 after ovulation, but this treatment also failed to induce luteolysis since plasma progestagen concentrations were maintained in all three mares. Two mares exhibited normal ovulatory intervals, while the third developed a...
Changes of blood metabolites in horses after racing, with particular reference to uric acid. Changes in concentration of a number of blood metabolites in 30 thoroughbred horses were recorded after an 1110 metre race. No significant changes occurred in blood urea or aspartate aminotransferase during the three hours after racing. Plasma sodium, potassium and calcium levels were increased immediately after racing but had returned to normal one hour after racing. Plasma phosphate showed a significant fall in concentration one hour after racing. Creatinine and lactic acid concentrations were elevated ten minutes after racing and although they subsequently decreased, the level of lactic aci...
Plasma cortisol in the horse, diurnal rhythm and effects of exogenous ACTH. Peripheral blood plasma Cortisol concentration and its diurnal variation was measured in 4 horses. Mean concentration of Cortisol during 24 hrs. was 42 ng/ml (s ± 20 ng/ml). Peak values occurred at 6 a.m. and the lowest values were observed at about 6 p.m. (mean 65 ng/ml and 20 ng/ml, respectively). Long-acting ACTH at a dose of 150 i.u. was given by intramuscular injection to the 4 horses. Peak Cortisol concentrations markedly exceeding the prestimulation level were obtained between 2 and 4 hrs. after injection. During the immediate 24 hrs. after these peaks, the mean Cortisol level was mark...
Effect of ovariectomy on pregnancy in mares. Pony mares were bilaterally ovariectomized at different stages of pregnancy between Days 25 and 210. Abortion or fetal resorption occurred within 2 to 6 days after operations in all 14 mares ovariectomized between Days 25 and 45 and after an interval of 10 to 15 days in 9 of 20 other ovariectomized between 50 and 70 days. All 12 mares ovariectomized on either 140 or 210 days carried their foals to normal term. The termination of early pregnancy was preceded by a loss of uterine tone and of a palpable uterine bulge. The mean length of gestation in all mares in which pregnancy was not interrupte...
