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.
Harkema JR, Robinson NE, Scott JB.Twelve Shetland ponies were fed a high-starch ration. Seven ponies which had a transitory metabolic acidosis developed laminitis 56 hours (+/- 3.5, SEM) after overfeeding. These ponies also developed persistent hypokalemia, hyperthermia, and increased heart rate 24 hours before the onset of lameness. Serum sodium, serum chloride, hematocrit, plasma volume, and blood volume were unchanged. At the onset of clinical signs of laminitis, cardiac output and blood pressure increased, but total peripheral resistance was unchanged. None of the measured or calculated values predicted the onset of lamini...
Kohn CW, Muir WW, Sams R.Plasma volume and extracellular fluid volume were determined in horses at rest and immediately after a standardized exercise test. Exercising during training demonstrated no detectable effect on plasma or extracellular fluid volume determinations when compared with resting values. An explanation of this finding and an argument for the proper analysis of plasma and extravascular fluid volumes are presented.
Silberzahn P, Quincey D, Rosier C, Leymarie P.Measurements every day or every other day showed that testosterone levels ranging from 15 to 70 pg/ml were higher at oestrus in 4 of the 6 mares studied. In these 4 mares, another testosterone peak occurred 11--13 days before the next oestrus either before (3 mares) or after the fall in progesterone levels.
Lucke JN, Hall GM.Blood samples were taken from 15 horses before and after a 50-mile ride to examine the changes occurring in some biochemical constituents. There was a significant (P less than 0.05) decrease in plasma potassium, calcium and magnesium concentrations and a rise in inorganic phosphate but there was no alteration in plasma sodium, chloride or protein levels or change in haematocrit. After the ride there was a highly significant (P less than 0.01) fall in blood glucose corresponding with increased lipolysis and a rise in plasma free fatty acids (P less than 0.001) and glycerol (P less than 0.001). ...
Reitnour CM.Utilisation of nitrogen was studied in 4 crossbred ponies. A latin square design was used to study the effects of corn gluten meal, casein or urea when added to a low protein basal diet. Apparent nitrogen digestion, nitrogen retention, total plasma protein, plasma urea and plasma-free amino acids were measured. The addition of corn gluten meal, casein or urea to the basal ration increased apparent digestion of nitrogen. Casein produced a significantly greater (P less than 0.05) nitrogen retention than corn gluten meal or urea. Plasma urea nitrogen increased significantly (P less than 0.01) in ...
Gahne B, Juneja RK.Cattle and horse plasma samples of known post-albumin types were radiolabelled with 14C-vitamin D3. These samples were then analysed by polyacrylamide gel electrophoresis, followed by autoradiography. The patterns observed were identical to those of post-albumin variants. The polymorphic post-albumin protein of cattle and horse was thus identified as the vitamin D binding protein and homologous to the Gc protein of human plasma.
Juneja RK, Gahne B, Sandberg K.Horizontal polyacrylamide gel electrophoreses, on 10% separation gel, of horse serum revealed polymorphism of the vitamin D binding protein (Gc protein) and another post-albumin protein (Pa). Family data supported the hypothesis that Gc and Pa types were controlled by autosomal codominant alleles. For both Gc and Pa proteins, the homozygous types showed a single fraction while the heterozygous type had two fractions. Pa types were found to be identical to the post-albumin types reported earlier by starch gel electrophoresis. Two Gc alleles, GcF and GcS, and three Pa alleles, Pa D, Pa F and Pa ...
Merritt AM, Kohn CW, Ramberg CF, Cimprich RE, Reid CF, Bolton JR.Five clinically normal, mature horses and 11 with chronic diarrhea were given 51Cr-tagged Cohn fraction V equine albumin intravenously. All urine and feces were collected separately, and blood for plasma analysis was taken periodically for 5 to 8 days after injection of the isotope. Plasma clearance of albumin into the intestinal tract of normal horses was calculated as 0.67 +/- 0.23 (SD) ml/kg of body weight/day, with 1.33 +/- 0.69% of the 51Cr dose appearing in the feces in 5 days. Of the 11 diarrheal horses, 8 had a plasma clearance of 0.49 +/- 0.21 ml/kg/day with 1.12 +/- 0.68% of the dose...
Alexander F.1. The effect on plasma, urinary and faecal electrolytes of frusemide and hydrochlorthiazide was measured in ponies, mean weight 180 kg. 2. The rapid loss in urine of large quantities of sodium had only a small effect on plasma sodium concentration. 3. Faecal sodium excretion was increased substantially after the administration of frusemide. 4. Frusemide increased faecal potassium during the 48 h following administration and faecal water in the 24/48 h period. It also produced a hypopotassaemia. 5. Hydrochlorthiazide increased faecal chloride during the 24 h after administration. 6. Frusemide ...
Mathieu HP, Mathieu-Nast C, Vrignaud C.A rapid and low cost radioimmunologic procedure for progesterone assay in mare plasma is proposed. Radioimmunoassay is performed directly on 10 microliter of unextracted plasma. Free progesterone is adsorbed on dextran-charcoal, then the aqueous phase is decanted and extracted by 1 ml of scintillation fluid. Counting is performed directly on this two-phase system. Results are comparable to those obtained with radioimmunoassays using extracted plasma.
Honstein RN, Monty DE.Field investigations were conducted under natural environmental conditions to determine the physiologic responses of rested, hydrated horses (Equus caballus) to the very hot, dry weather characteristic of the summer season in southern Arizona. The emphasis of the investigation was placed on those thermoregulatory mechanisms which are involved in the maintenance of homoiothermy. Rectal temperature of the horses studied remained relatively stable throughout the day, during both cool and hot weather seasons. However, when horses were exposed to hot summer temperatures, rectal temperature (heat st...
Garner HE, Hahn AW, Salem C, Coffman JR, Hutcheson DP, Johnson JH.Acute laminitis-hypertension was produced experimentally by carbohydrate overloading of the gastrointestinal tract in 8 horses, and the resulting hemodynamic changes were measured. Statistically significant (P less than 0.01) increases in cardiac output, left ventricular ejection rate, heart rate, and arterial pressure were related to statistically nonsignificant changes in peripheral resistance and a delayed (Obel grade 3 plus 24 hours) decrease in plasma volume. When compared with control values, the doubling of cardiac output and left ventricular ejection rate simultaneous with little or no...
Fernley RT.1. Angiotensin I converting enzyme from horse plasma has been extensively purified and shown to be homogeneous by disc-gel electrophoresis. 2. The metal ion involved in the catalytic reaction of the enzyme has been identified for the first time as zinc by atomic absorption spectrometry. 3. A number of other physicochemical properties of the enzyme are described and compared with results obtained by other investigators. The molecular weight was determined by gel filtration to be 113 000 daltons. The pH maximum was found to be 7-4. The chloride activation of the enzyme appears to act by facilita...
Rico AG, Braun JP, Benard P, El Hassan AA, Cazieux A.In the horse, gamma-glutamyl transferase (GGT) was found to be mainly located in the kidneys, liver and pancreas. As renal lesions are followed by a urinary escape of enzyme, it can be assumed that if there are raised serum enzyme levels then the source will be chiefly from the liver and pancreas. In the blood, GGT can be measured either in plasma or serum. Its mean level in 58 horses was 12 U/L. This level was not affected by moderate dilution or slight haemolysis and its activity was only slightly decreased by storage at--30 degrees C. The relative hepatic specificity of this enzyme and its ...
Carlson GP, Harrold DR.A highly significant correlation between the water content and protein concentration of equine serum and plasma samples was demonstrated over a wide range of concentrations. A close correlation was also observed between protein concentration as estimated by refractometry and as determined by the biuret procedure for equine serum and plasma samples.
Gilmour JS, Mould DL.Plasma, serum and cells were prepared from blood taken from acute cases of grass sickness, and plasma was fractionated by gel filtration and salt precipatation. These preparations were all tested for neurotoxic activity by injection into ponies. Plasma and serum were found to produce the neurohistological changes seen in grass sickness, as was a plasma protein fraction of molecular weight 30,000 or greater. Activity was retained following storage at--75 degrees C for 15 months. Plasma given orally to a pony produced no detectable effect, nor was activity demonstrated following the injection of...
Tobin T, Blake JW, Valentine R.The plasma half-life of phenylbutazone in horses was not increased after pretreatment with chloramphenicol or quinidine, but was increased after oxyphenbutazone. This increased plasma half-life after oxyphenbutazone is consistent with observations in other species and suggests that oxyphenbutazone inhibits the metabolism of phenylbutazone in horses. Lack of inhibition of phenylbutazone metabolism in the horse by chloramphenicol and quinidine is inconsistent with results obtained in other species.
Roberts BL, Blake JW, Tobin T.Horses pretreated with 6.6 mg/kg of phenylbutazone were injected with 1 mg/kg of furosemide intravenously. Furosemide had no clinically significant effect on either plasma levels or plasma half-life of phenylbutazone. Furosemide reduced urinary levels of phenylbutazone 18-fold to concentrations which may result in inconsistent drug detection in routine screening tests. The results show that it is not possible to monitor compliance with phenylbutazone medication rules by means of urinalysis alone if the use of furosemide is permitted. Furosemide treatment, however, does not interfere with monit...
Evans JA, Lambert MB, Miller J.The anti-inflammatory drug Ibuprofen [(+/-)-2-(p-isobutylphenyl) propionic acid] was estimated in the blood and urine of a horse using gas-liquid chromatography of the silylated derivative. Levels of the drug in the two body fluids were measured over a period of about 24 hours after administering a 12 gm dose of Ibuprofen. Plasma peak levels were observed within 30 to 60 min, and the drug was no longer detectable in the plasma by 8 hr. Urinary peak levels were observed 200 to 300 min after dosing, and the drug was no longer detectable in the urine by about 28 hr. It was observed that only 2% t...
Tobin T, Blake JW, Sturma L, Arnett S.Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma. These properties are consistent with hydrolysis being due to plasma esterases operating at less than saturating procaine concentrations. These esterases ...
Tobin T, Blake JW.Since procaine has both local anaesthetic and central stimulant actions its presence in the blood or urine of racing horses is forbidden. After rapid intravenous injection of procaine HC1 (2.5 mg/Kg) in thoroughbred mares plasma levels of this drug fell rapidly (t 1/2 alpha = 5 min) and then more slowly (t 1/2 beta = 50.2 min). These kinetics were well fitted by a two compartment open model (Model I). This model gave an apparent Vdbeta for procaine in the horse of about 3,500 litres. Since procaine was about 45% bound to equine plasma protein this gives a true Vdbeta for procaine of about 6,50...
Blake JW, Tobin T.Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four "esses" of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of ...
Thompson DL, Reville SI, Derrick DJ.Five mature Quarterhorse mares were bled every 30 min for 25 h on day 50 of pregnancy to determine the short-term mode of secretion of equine chorionic gonadotropin (eCG). Three other mares with persistent endometrial cups after abortion were administered gonadotropin releasing hormone (GnRH; 1.0 mug/kg of body weight) and were bled immediately prior to and at 15, 30, 45, 60, 90, 120, 180 and 240 min after GnRH. Concentrations of eCG in plasma of pregnant mares were constant over the 24-h period; the variation of each mare's individual values was no greater (P>.05) than the predicted random...
Mischke R, Junker J, Deegen E.The sensitivity of commercial prothrombin time (PT) tests was assessed based on a dilution series of equine pooled plasma (EPP) (experiment 1) and on 40 equine plasma samples with reduced activity of coagulation factors II, V, VII and X (experiment 2). Two different PT reagents (reagent 1, human placental thromboplastin; reagent 2, recombinant human tissue factor) were used according to the manufacturers' instructions (standard test, PT([ST])) and compared to a modified test procedure (modified test, PT([MT])) using sample dilution and fibrinogen addition. In all samples, sensitivity was lower...
Calatroni A, Avenoso A, Ferlazzo AM, Lindner A, Campo GM.Plasma glycosaminoglycans (GAGs) were isolated and purified by chromatographic procedures in healthy humans and horses before and after physical exercise. A weak anion exchange resin was used to separate polyanions. Humans exercised on a cycloergometer, while horses were exercised on a treadmill and in show jumping competition. Some GAGs were isolated from untreated plasma and operationally defined as native proteoglycans (PGs), while the total GAG amount was isolated from mild alkali treated plasma. Plasma GAG concentrations in terms of galactosamine and galactose, the respective components o...
Henion JD, Maylin GA.A sensitive, quantitative method has been developed for the determination of hydrochlorothiazide in equine plasma and urine. Thin-layer chromatography is used to screen for the presence of the drug in unknown samples. The TLC screening methods described provide minimum detection limits of 50 ng/mL in plasma and 25 ng/mL in urine. A silica micro chromatography column is used to clean up ethyl acetate extracts for HPLC analysis and mass spectral confirmation. An internal standard, trichloromethiazide, is used to derive quantitative data at concentrations as low as 25 ng/mL for plasma disappearan...
Garcia P, Paris AC, Leufroy A, Popot MA, Bonnaire Y.A quantitative method, using LC/ESI-MS(n) with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MS(n). The efficiency of extraction combined with the sensitivity and the selectivity of MS(n) allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratr...
Cunningham FM, Andrews M, Landoni MF, Lees P.Calcium ionophore A23187 induced time and concentration dependent production of immunoreactive leukotriene (LT) B4 by equine heparinized whole blood in vitro. Time dependent production of immunoreactive LTB4 by equine neutrophils and immunoreactive LTC4 by equine eosinophils in vitro was also demonstrated. The 5-lipoxygenase activating protein (FLAP) inhibitors, BAY X 1005 and BAY Y 1015, produced concentration dependent inhibition of ionophore-induced LTB4 synthesis by equine whole blood (mean +/- SEM IC50s n = 5; 6.14 +/- 0.28 microM vs. 12.30 +/- 0.75 microM for BAY Y 1015 and BAY X 1005, r...
Reitnour CM, Salsbury RL.Protein digestion, nitrogen retention, plasma protein, plasma urea, and plasma-free amino acids were determined for ponies fed 3 different protein supplements. Substitution of casein, corn gluten meal, or corn gluten meal plus lysine for a portion of the cornstarch in a low-protein basal ration increased apparent digestion of protein. Substitution with either casein or corn gluten meal plus lysine produced a significant increase (P less than 0.05) in nitrogen retention, whereas the corn gluten meal substitution did not. Nitrogen retention, expressed as percentage of nitrogen absorbed, was incr...
Ferrante PL, Freeman DE, Ramberg CF, Kronfeld DS.Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after IV administration to healthy mares deprived of food for 12 and 96 hours. Urinary excretion of D-xylose was measured over a 15-hour period after administration. The plasma D-xylose concentrations in this study were in the range found after oral tolerance testing. The disposition of D-xylose was described by a two-compartment model with linear kinetic characteristics. Total volume of distribution decreased significantly (P < 0.025) from 0.270 L/kg of body weight after the 12-hour period of food depriv...
Sisodia CS, Kramer LL, Gupta VS, Lerner DJ, Taksas L.Pharmacological disposition of chloramphenicol was studied in horses. Minimum levels of the antibiotic (greater than or equal to 5 mu g/ml) in blood or plasma recommended to combat infections could not be achieved by 4.4 and 8.8 mg/kg I.V. or 30 and 50 mg/kg I.M. or 30 mg/kg oral (as palmitate salt) doses of chloramphenicol. Increasing the dose to 19.8 and 26.4 mg/kg I.V. provided such levels for about two and three hours respectively. A combination of 20 mg/kg I.V. and 30 mg/kg I.M. administered simultaneously did not provide more prolonged levels than 26.4 mg/kg I.V. alone. Chloramphenicol s...
Ducharme NG, Dill SG, Shin SJ, Schwark WS, Ducharme GR, Beilman WW.This preliminary study evaluated phenoxymethyl penicillin (Penicillin V) as an alternative to parenteral administration of penicillin in horses. Penicillin V was administered orally to five horses at two different doses and plasma levels of the drug were determined at timed intervals. The results were evaluated by regression analysis. Following the administration of penicillin V at a dose of 66,000 IU/kg or 110,000 IU/kg, the mean peak plasma levels obtained were 1.55 micrograms/mL and 2.34 micrograms/mL respectively. A plasma level two to four times above the minimal inhibitory concentration ...
Kavazis AN, Sobota JS, Kivipelto J, Porter MB, Colahan PT, Ott EA.A diverse group of studies, which are equine exclusive, indicate that ribose administered to myocardial and skeletal muscle tissue stimulates ATP production and recovery. This study investigated the effects of ribose supplementation on blood and muscle metabolites and performance in Thoroughbred geldings performing a maximal treadmill standardised exercise test (SET). In Experiment 1, 6 conditioned Thoroughbred geldings performed a baseline SET and horses were assigned to one of 2 experimental treatment groups, placebo or ribose, based on VO2max. The placebo treatment group received 0.07 g glu...
Miller PA, Lawrence LM.Six mature Quarter Horse mares were used in a crossover design to assess the effect of dietary protein level on metabolic response to exercise. After a 2-wk adaptation period to either a 12.9% (control) or an 18.5% CP (high-protein) diet, each mare performed a standard exercise test. The test consisted of a 15-min exercise period at 4.5 m/sec on a 9% grade motorized treadmill. Exercise resulted in an increase in heart rate (P less than .001), but there was no difference (P less than .05) between dietary treatments. In the jugular vein, lactate increased (P less than .01) from 6.3 to 52.0 mg/10...
Bardell DA, Archer DC, Milner PI.Colic remains a life-threatening condition in the horse. Ischaemia and reperfusion following correction of small intestinal strangulation may produce oxidative stress. The ability to withstand oxidative stress depends on antioxidant levels and may be linked to horse survival. Objective: To measure peripheral antioxidant levels in horses undergoing exploratory laparotomy with small intestinal strangulation. Methods: Case-control study. Methods: Blood and plasma were collected from horses undergoing exploratory laparotomy for small intestinal strangulation and stored at -80°C. Controls involved...
Viu J, Armengou L, Ríos J, Muñoz A, Jose-Cunilleras E.To determine the strong ion difference (SIDa ) and total nonvolatile weak buffers (ATOT ) in healthy foals during the first year of life and to compare reference biochemistry laboratory with analyzers available during emergency hours. Methods: Prospective study performed over 2 years. Methods: University teaching hospital. Methods: Two hundred thirty-six healthy foals distributed in 6 groups: A (21 days-2 months), B (2-3 months), C (3-6 months), D (6-9 months), E (9-12 months), and 33 neonatal foals (< 21 days old). Methods: Blood samples were obtained to determine L-lactate, sodium, potass...
Luo Y, Rudy JA, Uboh CE, Soma LR, Guan F, Enright JM, Tsang DS.The method describes quantification and confirmation of flunixin in equine plasma by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC/Q-TOF/MS/MS). Samples were screened by enzyme-linked immunosorbent assay (ELISA) and only those samples presumptively declared positive were subjected to quantification and confirmation for the presence of flunixin by this method. The method is also readily adaptable to instrumental screening for the analyte. Flunixin was recovered from plasma by liquid-liquid extraction (LLE). The sample was diluted with 2 ml saturated phosphate buffer (pH ...
Kim JY, Choi MH, Kim SJ, Chung BC.A high-performance liquid chromatographic-tandem mass spectrometric (HPLC/MS/MS) method for the determination of 19-nortestosterone and its esters (cyclopentanepropionate, phenylpropionate, and decanoate) in equine plasma is achieved using an atmospheric pressure chemical ionization (APCI) interface in selected reaction monitoring (SRM) mode. The two internal standards used were 16,16, 17-(2)H(3)-19-nortestosterone for 19-nortestosterone and methenolone acetate for its esters. The steroids studied were extracted from plasma samples with a mixture of diethyl ether/n-hexane (9:1, v/v). The quant...
Watson TD, Burns L, Freeman DJ, Packard CJ, Shepherd J.1. Apolipoprotein A-I dependent lecithin:cholesterol acyl transferase (LCAT) activity was identified in equine lipoprotein deficient plasma (LPDP). 2. LCAT activity showed no breed or sex variation, and was unaltered postprandially. 3. There was no significant cholesteryl ester transfer activity in equine LPDP. 4. Hydrophobic interaction chromatography on phenyl sepharose failed to unmask transfer activity or identify an inhibitor of cholesteryl ester transfer. 5. In 12 Shetland ponies, plasma high density lipoprotein (HDL) concentrations were positively correlated with those of triglyceride, ...
Nadal MR, Thompson DL, Kincaid LA.Two experiments were conducted to determine 1) the prolactin response to different kinds of feedstuffs in stallions and 2) the effects of total feed deprivation on prolactin secretion in mares and its interaction with the prolactin response to feeding. Experiment 1 was performed with stallions as a 6 x 6 Latin square: A) no feed; B) pelleted feed fed to meet 82.5% of the horses' CP requirements; C) pelleted feed at 25% of the amount in B; D) pelleted feed as in B plus water ad libitum; E) cracked corn at the weight in B; and F) chopped alfalfa at the weight in B. The positive prolactin respons...
Tennent-Brown BS, Goetz TE, Manohar M, Hassan AS, Freeman DE, Bundy JS, Evans MR.Hyperhydration, prior to prolonged moderate-intensity exercise simulating the 2nd day of a 3-day equestrian event (E3DEC), may induce arterial hypoxaemia detrimental to performance. Objective: Because moderate-intensity exercise does not induce arterial hypoxaemia in healthy horses, the effects of pre-exercise hypervolaemia on arterial oxygenation were examined during a prolonged exercise protocol. Methods: Blood-gas studies were carried out on 7 healthy, exercise-trained Thoroughbred horses in control and hyperhydration experiments. The study conformed to a randomised crossover design. The se...
el-Banna HA.The pharmacokinetic aspects of sulphadimidine were studied in clinically healthy (control) and Flunixin-medicated horses after a single intravenous and oral administration of 100 mg/kg body weight. Plasma sulphadimidine concentration were determined by high-performance liquid chromatography (HPLC). Following the intravenous injection, all plasma sulphadimidine data were best approximated by a two-compartment open model using sequential, weight non-linear regression. Flunixin induced a 67% increase in the rate of sulphadimidine return to the central compartment from peripheral tissues (K21) and...
Fey K, Klatt P, Schmidt H, Sasse HH.Five healthy horses were given a sulfadoxine/trimethoprim combination (Borgal, Hoechst AG) i.v. on day 1. The next ten days the horses got once a day a sulfadimethoxine/trimethoprim combination orally (Trafigal, Hoechst AG). The doses were given as recommended. One horse received no medicaments for control. On each horse six bronchoalveolar lavages were performed. Blood samples were taken to calculate blood levels and elimination half lives. To determine the amount of substances in lavage fluid and plasma the high performance liquid chromatography (HPLC) was used. Regularly low quantities of s...
Schwarzwald CC, Sams RA, Bonagura JD.The pharmacokinetics of diltiazem were determined in eight healthy horses. Diltiazem HCl, 1 mg/kg i.v., was administered over 5 min. Venous blood samples were collected at regular intervals after administration. Plasma concentrations of diltiazem and desacetyldiltiazem were determined by high-performance liquid chromatography. A second, putative metabolite was detected, but could not be identified due to the lack of an authentic standard. Data were analyzed by nonlinear least-squares regression analysis. The median (minimum-maximum) peak plasma concentration of diltiazem was 727 (539-976) ng/m...
Saito A, Kitano Y.The inhibition of cysteine proteinase (papain) by human, bovine, horse, rabbit, guinea pig, rat, hamster, and mouse plasma, and pig, sheep, goat, and dog sera was investigated. The rat and mouse plasma and the pig serum showed such high inhibitory capacity as 813, 380, and 508%, respectively, of the human plasma. On the other hand, the horse, guinea pig, and rabbit plasma indicated 36, 40, and 54%, respectively, of the human plasma. A cysteine proteinase inhibitor (s) was separated from alpha-macroglobulin by Sephacryl S-300, and the inhibitory activity of all of the mammalian plasma/sera exce...
Garcia MC, Ginther OJ.Six pony mares were ovariectomized (OVX) on day 16 of diestrus during June and July, 1972, to study short term changes in plasma luteinizing hormone (LH) concentrations. Plasma LH was higher (P less than .05) 3 days after OVX (1.76 ng/ml) than the day after OVX (1.01 ng/ml), and a gradual increase occurred over the first 2 weeks. Elevated plasma LH concentrations similar to mid-estrus levels were present from the 2nd to 11th week post-OVX. In another experiment, the same 6 OVX mares were bled once a month from February, 1973, to January, 1974, to study long-term changes in plasma LH in relatio...
McElligott EM, Sommardahl CS, Cox SK.OBJECTIVE To determine the pharmacokinetics of chloramphenicol base after PO administration at a dose of SO mg/kg (22.7 mg/lb) in adult horses from which food was not withheld. DESIGN Prospective crossover study. ANIMALS 5 adult mares. PROCEDURES Chloramphenicol base (SO mg/kg) was administered PO to each horse, and blood samples were collected prior to administration (0 minutes) and at 5, 10, 15, and 30 minutes and 1, 2, 4, 8, and 12 hours thereafter. Following a washout period, chloramphenicol sodium succinate (25 mg/kg [11.4 mg/lb]) was administered IV to each horse, and blood samples were ...
Young DB, Ewing PJ, Burrows GE, Lessley BA, Clarke CR, Shawley RV.Phenylbutazone given during the perisurgical period has been reported to increase the intensity and duration of thiamylal anaesthesia in horses. A possible mechanism of competitive plasma protein binding has been suggested. The purpose of the present study was to experimentally reproduce the phenomenon of increased intensity and/or duration of thiamylal anaesthesia and to determine if there is competitive displacement of plasma protein bound thiamylal by phenylbutazone. Six ponies each received one of three treatments, 11 mg/kg intravenous (i.v.) thiamylal; 8.8 mg/kg i.v. phenylbutazone; and 1...
Bonnaire Y, Dehennin L, Plou P, Toutain PL.A pharmacological dose of a long-acting testosterone ester, testosterone hexahydrobenzoate, was administered intramuscularly to two mares. The time course for some characteristic metabolites in blood and urine was then studied using an analytical method based on gas chromatography-mass spectrometry associated with stable isotope dilution. Among the plasma analytes, testosterone glucuronide was found to be the most adequate indicator for the monitoring of exogenous testosterone up to 2 weeks postadministration if a threshold value of 200 ng/L was applied. In urine, the simultaneous measurement ...
Kristinsson J, Thordarson TH, Johannesson T.The pharmacokinetics of lignocaine was studied in four Icelandic horses after infiltration anaesthesia. A total of 240 mg of the drug was injected on either side of the left foreleg, over the medial and lateral branches of the palmar nerve. Blood samples were collected up to seven hours after injection and the concentrations of the drug in plasma were determined by gas chromatography/mass spectrometry. The results showed that lignocaine was rapidly absorbed. A mean maximum concentration of 232 ng/ml was observed after 20 minutes. In three of the horses the decline in the plasma concentration o...
Trevisiol S, Moulard Y, Kaabia Z, Delcourt V, Loup B, Garcia P, Boyer S, Dauriac K, Groseille G, Rouger S, Narbe R, Popot MA, Bailly-Chouriberry L.Ciclesonide (CIC) is the first inhaled highly potent corticosteroid that does not cause any cortisol suppression. It has been developed for the treatment of asthma in human and more recently in equine. CIC is the active compound of Aservo® EquiHaler® (Boehringer Ingelheim Vetmedica GmbH), the pre-filled inhaler generating a medicated mist based on Soft Mist™ technology. This prodrug is rapidly converted to desisobutyryl-ciclesonide (des-CIC), the main pharmacologically active compound. Due to its anti-inflammatory properties, CIC is prohibited for use in horse competitions. To set up an ap...
Gallicano KD, Park HC, Young LM.A sensitive method was required to analyze low levels of camphor in equine urine and plasma. Camphorated oil (20% w/w camphor) was administered topically (6 g) and intratracheally (1 g) to standardbred mares. The drug was extracted from urine and plasma by diethyl ether and analyzed as its 2,4-dinitrophenylhydrazone derivative by reverse phase HPLC with UV detection. The UV detector was set at 368.5 nm and the samples were eluted from the C18 column by 82% acetonitrile in water. The detection limit achieved was about 10 ng/mL urine and about 20 ng/mL plasma. After topical administration, only ...
