Intravenous administration in horses involves the delivery of substances directly into the bloodstream through a vein. This method is used to administer fluids, medications, and nutrients efficiently, ensuring rapid distribution throughout the body. It is commonly employed in veterinary practice for rehydration, anesthesia, and treatment of various medical conditions. The technique requires skill and knowledge to ensure proper vein selection and catheter placement, minimizing the risk of complications such as infection or thrombosis. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and potential complications associated with intravenous administration in equine medicine.
Clarke KW, Taylor PM.Detomidine, given intravenously at doses of 5 to 30 (mean 13) micrograms/kg bodyweight (bwt), provided adequate sedation for a variety of clinical procedures in 93 per cent of administrations, and improved the ease of handling in the remaining animals. Side effects of ataxia and bradycardia were minimal at the lower dose rates. Higher doses were required for intramuscular use. In experimental trials 10 and 20 micrograms/kg bwt resulted in deep sedation and also significant hypertension and bradycardia of over 15 mins duration. Current literature on the use of detomidine in horses is reviewed.
Delbeke FT, Debackere M, Desmet N, Stevens M.Concentrations of the potent diuretic bumetanide were determined by a sensitive high performance liquid chromatographic procedure in plasma and urine from horses following intravenous and intramuscular administration of a dose rate of 15 micrograms/kg. The elimination half-life was found to be 6.3 min, the volume of distribution at steady state 68 ml/kg and the total plasma clearance 10.9 ml/min/kg. The onset of diuresis occurred within 15 min and diuresis was no longer apparent 1 h after i.v. administration. Given by the intramuscular (i.m.) route, bumetanide was rapidly absorbed; bioavailabi...
Sweeney RW, Sweeney CR, Soma LR, Woodward CB, Charlton CA.Serum and peritoneal fluid concentrations of metronidazole were determined in 6 healthy adult horses given the drug (25 mg/kg) by IV or oral routes. The disposition of metronidazole in horses given the drug by the IV route conformed to a 2-compartment model with a distribution half-life of 0.16 hours, an elimination half-life of 2.9 hours, and a body clearance of 0.40 +/- 0.05 L/kg/hr. The oral absorption half-life was 0.40 hours, and the bioavailability, 85.0 +/- 18.6%. Peritoneal fluid concentrations were approximately equal to serum concentrations at all times, regardless of the route of ad...
Blythe LL, Craig AM, Christensen JM, Appell LH, Slizeski ML.Dimethyl sulfoxide (DMSO) was administered IV to 6 Thoroughbred horses at 2 dosages: 1.0 g/kg and 0.1 g/kg. The pharmacokinetics seemed linear, with biological half-lives of 8.6 +/- 0.3 hours and 9.8 +/- 2.2 hours for the 1.0 g/kg and 0.1 g/kg dosages, respectively. This was further substantiated by mean residence times of 9.8 +/- 0.44 hours and 13.8 +/- 4.25 hours, areas under the curve of 12.55 +/- 1.42 mg/ml/hr and 1.63 +/- 0.49 mg/ml/hr, and the clearances of 0.081 +/- 0.009 L/kg/hr and 0.066 +/- 0.022 L/kg/hr for the large and small dosages, respectively. At 12 hours after 1.0 g/kg was ad...
Brown MP, Gronwall RR, Houston AE.Four healthy adult mares were each given a single injection of sodium cefoxitin (20 mg/kg of body weight, IV), and serum cefoxitin concentrations were measured serially during a 6-hour period. The mean elimination rate constant was 1.08/hour and the elimination half-life was 0.82 hour. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.12 L/kg and 259 ml/hr/kg, respectively. Each mare and 2 additional mares were then given 4 consecutive IM injections of sodium cefoxitin (400 mg/ml) at a dosage of 20 mg/kg. Cefoxitin concentrations in serum, ...
Bowman KF, Dix LP, Riond JL, Riviere JE.Pharmacokinetics of ampicillin sodium (11 mg/kg), gentamicin sulfate (2.2 mg/kg), and combination ampicillin sodium-gentamicin sulfate were determined for serum and synovia of healthy horses given single-dose IV injection and were not found to be different from those from other reports; however, a prolonged terminal gamma-phase for gentamicin (8,498 +/- 1,842 minutes) in serum of horses was found to exist. Pharmacokinetic interaction between combination ampicillin sodium-gentamicin sulfate was not observed int he serum or synovia. Prediction of ampicillin sodium or gentamicin sulfate concentra...
Edwards GB.Intraoperative techniques for assessing the viability of ischaemic bowel are discussed. Intravenous administration of sodium fluorescein appears useful but further investigation of the method is required. Methods of resection and anastomosis of small intestine are described and illustrated, including the use of automatic stapling instruments.
Denkhaus M, Van Amstel S.Non-commercial, endotoxin positive, intravenous fluids as well as a commercially available intravenous fluid were given to clinically normal horses. Endotoxin-positive fluids caused clinical signs attributable to endotoxaemia. Leukopenia, preceded by a fluctuating white cell count, was observed in horses showing clinical signs. The commercial intravenous fluid had no effect on the white cell count or on the clinical state. Precautions to be taken and recommendations are made with regard to the monitoring of horses in which one might be forced to use non-commercial intravenous fluids.
Wernette KM, Hubbell JA, Muir WW, Sams RA.The cardiopulmonary effects of 3 dosages of doxapram hydrochloride (0.275 mg/kg, 0.55 mg/kg, and 1.1 mg/kg, IV) were studied in 6 adult horses. Doxapram given IV significantly (P less than 0.05) decreased PaCO2 and increased respiratory rate, cardiac output arterial blood pressures (systolic, mean, and diastolic) arterial pH, and PaO2 at 1 minute after each dose was administered. Heart rate and mean and diastolic pulmonary arterial blood pressure were significantly (P less than 0.05) increased 1 minute after the 2 larger dosages of doxapram were given (0.55 mg/kg and 1.1 mg/kg, IV), but not af...
Snyder JR, Pascoe JR, Hietala SK, Holland M, Baggot DJ.Gentamicin sulfate (2.2 mg/kg of body weight, IV) was given to anesthetized horses. Jejunal and large colon tissue samples (1 g), serum, and urine were collected over a 4-hour period. Maximum gentamicin concentrations in serum (10.06 +/- 2.85 micrograms/ml) occurred at 0.25 hours after injection. Maximum gentamicin concentrations in the large colon (4.13 +/- 1.80 micrograms/ml) and jejunum (2.26 +/- 1.35 micrograms/ml) occurred in horses at 0.5 and 0.33 hours, respectively. Tissue concentrations decreased in parallel with serum concentrations and were still detectable at the end of the 4-hour ...
Brown MP, Gronwall RR, Houston AE.Six healthy adult horse mares were each given a single injection of sodium cephapirin (20 mg/kg of body weight, IV), and serum cephapirin concentrations were measured serially over a 6-hour period. The mean elimination rate constant was 0.78 hour-1 and the elimination half-life was 0.92 hours. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.17 L/kg and 598 ml/hour/kg, respectively. Each mare was then given 4 consecutive IM injections of sodium cephapirin (400 mg/ml) at a dosage level of 20 mg/kg. Cephapirin concentrations in serum, synovi...
Orr JA, Erichsen DF, Shirer HW, Allen PL, Payne PA.The aim of this study was to determine whether increases in ventilation would occur during intravenous acid infusion even if systemic arterial pH was held constant. In six awake ponies, HCl (500 ml, approximately 0.312 M) was infused into the right atrium at a total dose of 1.0 meq/kg over 18 min while an equivalent dose of NaOH was infused into the left heart to restore systemic arterial pH to normal. Total ventilation increased at the onset of the infusion and remained elevated although systemic arterial pH was normal to slightly alkaline. The increase in ventilation during the initial 2 min...
Tobin T, Chay S, Kamerling S, Woods WE, Weckman TJ, Blake JW, Lees P.Phenylbutazone is an acidic, lipophilic, non-steroidal anti-inflammatory drug (NSAID). It is extensively metabolized in the horse. The metabolites so far identified, oxyphenbutazone, gamma-hydroxyoxyphenbutazone, account for some 25-30% of administered dose over 24 h. The plasma half-life of phenylbutazone and termination of its pharmacological action are determined primarily by its rate of hepatic metabolism. Phenylbutazone acts by inhibiting the cyclooxygenase enzyme system, which is responsible for synthesis of prostanoids such as PGE2. It appears to act on prostaglandin-H synthase and pros...
Maitho TE, Lees P, Taylor JB.The disposition of phenylbutazone (4.4 mg/kg), administered intravenously to six Welsh Mountain ponies, was described by a two-compartment open model. Pharmacokinetic parameters were not significantly different after morning dosing in comparison with afternoon dosing. When phenylbutazone (4.4 mg/kg) was administered orally to the same ponies, marked variations in time to peak concentrations were produced with different feeding schedules. When access to hay was permitted before and after dosing, the mean time to peak concentration was 13.2 +/- 1.2 h and double peaks in the plasma concentration-...
Trim CM, Hanson RR.The intravenous administration of xylazine (1.1 mg/kg bodyweight) in six ponies resulted in a significant increase in urine output over two hours, with maximum flow occurring between 30 and 60 minutes after injection. Urine specific gravity, osmolality and glucose concentration decreased. Renal clearance of endogenous creatinine was unchanged. Significant increases in the excretion of potassium and chloride occurred. Plasma glucose concentration was increased 30 minutes after the administration of xylazine by a mean value of 37 per cent. Serum osmolality and sodium, potassium and chloride conc...
Donecker JM, Sams RA, Ashcraft SM.The pharmacokinetics and bioavailability of probenecid given IV and orally at the dosage level of 10 mg/kg of body weight to mares were investigated. Probenecid given IV was characterized by a rapid disposition phase with a mean half-life of 14.0 minutes and a subsequent slower elimination phase with a mean half-life of 87.8 minutes in 5 of 6 mares. In the remaining mare, a rapid disposition phase was not observed, and the half-life of the elimination phase was slower (172 minutes). The mean residence time of probenecid averaged 116 minutes for all 6 mares and 89.2 minutes for the 5 mares with...
Coyne CP, Hornof WJ, Kelly AB, O'Brien TR, DeNardo SJ.Two methods were analyzed for the rapid extraction of equine fibrinogen from fresh plasma, using ammonium sulfate-sodium phosphate buffer. Fibrinogen from each of these 2 methods was then radiolabeled with 125I (half-life = 60.2 days, gamma = 35 keV), using monochloroiodine reagent. Mean protein-bound activity was 98.5% and mean clottable radioactivity was 94.1%. Radiolabeled fibrinogen administered IV to 15 horses had an overall mean (+/- SD) plasma half-life of 4.95 +/- 0.44 days.
Semrad SD, Hardee GE, Hardee MM, Moore JN.The pharmacokinetics and inhibition of prostaglandin synthesis in conscious horses given various dosages of flunixin meglumine were studied. Plasma concentrations of flunixin were measured by high-performance liquid chromatography, and serum thromboxane B2 and 6-keto prostaglandin F1 alpha were quantitated by radioimmunoassay. Within the dosage range studied, linear pharmacokinetics were achieved. After IV administration of flunixin (1.1 mg/kg, 0.25 mg/kg, 0.1 mg/kg), significant suppression of serum thromboxane generation persisted for 12, 4, and 3 hours, respectively. Repeated administration...
Ayres JW, Pearson EG, Riebold TW, Chang SF.The pharmacokinetics of theophylline and dyphylline were determined after IV administration in horses. In a preliminary experiment, the usual human dosage (milligram per kilogram) of each drug was given to 1 horse. Results were used to calculate dosages for a cross-over study, using 6 horses for each drug. Theophylline plasma concentrations decreased triexponentially in 5 of 6 healthy horses after IV infusion of 10 mg of aminophylline/kg of body weight for 16 to 32 minutes. In the 6 horses, total body elimination rate constants were variable, and the half-life of theophylline was 9.7 to 19.3 h...
Ginther OJ, Bergfelt DR, Scraba ST, Pivonka PR, Nuti LC.The effect on reproduction of the plant derivative 6-methoxybenzoxazolinone (6-MBOA), which stimulates reproductive function in voles, was tested in pony mares, laboratory mice and rats, and mink. There was not a significant effect of intravenous injections of 6-MBOA on the ovarian follicles during the transition between the anovulatory and ovulatory seasons in mares. No significant effect of intraperitoneal injections of 6-MBOA on the weight of uterus or ovaries was found in eight-week-old mice, failing to confirm the results of an earlier report. In immature white rats, 6-MBOA treatment resu...
Trim CM, Colbern GT, Martin CL.Intraocular pressure was measured with a MacKay-Marg tonometer in eight horses following auriculopalpebral nerve block and topical application of lignocaine. Measurements were recorded before and after xylazine, 1.1 mg/kg intravenously, every two minutes for 16 minutes after administration of ketamine, 2.2 mg/kg intravenously, and after recovery from anaesthesia. Before xylazine, intraocular pressure was 17.1 +/- 3.9 and 18.4 +/- 2.2 mm Hg in the left and right eyes, respectively. Intraocular pressure tended to decrease after administration of xylazine and ketamine, with a significant decrease...
Gerken DF, Sams RA.The effects of i.v. chloramphenicol sodium succinate on the pharmacokinetics of i.v. phenylbutazone in six healthy adult horses were investigated. Administration of chloramphenicol sodium succinate to mares reduced mean (+/- SD) phenylbutazone clearance from 0.600 +/- 0.222 to 0.339 +/- 0.123 ml/min per kg and increased mean (+/- SD) half life from 244 +/- 59.8 to 371 +/- 80.8 min and mean residence time from 333 +/- 86.2 to 533 +/- 124 min. The mean steady-state volume of distribution of phenylbutazone was unchanged, with mean (+/- SD) values of 187 +/- 28.9 ml/kg in control animals and 170 +...
Ruoff WW, Sams RA.The pharmacokinetics and bioavailability of cephalothin given to 6 horse mares at a dosage level of 11 mg/kg of body weight IV or IM were investigated. The disposition of cephalothin given IV was characterized by a rapid disposition phase with a mean half-life of 2.89 minutes and a subsequent slower elimination phase with a mean half-life of only 14.7 minutes. The mean residence time of cephalothin was 10.6 +/- 2.11 minutes. The total plasma clearance of cephalothin averaged 13.6 ml/min/kg and was caused by metabolism and renal elimination. Renal clearance of cephalothin averaged 1.32 ml/min/k...
Errecalde JO, Button C, Mülders MS.A single intravenous administration of theophylline as aminophylline at 10 mg/kg to four mares induced a diuresis in which maximal urine production was more than seven times the control volume. The diuretic effect was maximal within the first hour post-administration, and lasted approximately 6 h. Theophylline resulted in dose-related tachycardia, polypnoea and nervous symptoms (tactile, visual and auditory hypersensitivity, muscle tremor, sweating) in normal mares, but had only minor effects on arterial and central venous blood pressures, intrapleural pressure, red blood cell variables and pl...
Nouws JF, Vree TB, Baakman M, Driessens F, Smulders A, Holtkamp J.The plasma disposition of sulfadimidine (SDM) and its metabolites N4-acetylsulfadimidine (N4-SDM), 6-hydroxymethyl-4-methyl-pyrimidine (SCH2OH) and 5-hydroxy-4,6-dimethyl-pyrimidine (SOH), was studied in three horses following intravenous administration of SDM at dose levels of 20 and 200 mg/kg in cross-over trials. The percentages of N4-SDM (0.58-0.90%), SOH (0.83-6.75%) and SCH2OH (0.38-0.71%) in plasma, expressed as a percentage of the total sulfonamide concentration, were small and their plasma concentrations were parallel with SDM from 4 h following administration. At high doses (200 mg/k...
Nolan AM, Hall LW.The use of propofol, solubilised in a non-ionic emulsifying agent, for the induction and maintenance of anaesthesia in experimental ponies was assessed. Pilot studies revealed that premedication with xylazine (0.5 mg/kg bodyweight [bwt]) intravenously (iv) followed by propofol (2.0 mg/kg bwt) iv provided a satisfactory smooth induction. Two infusion rates (0.15 mg/kg bwt/min and 0.2 mg/kg bwt/min) were compared for maintenance of anaesthesia. An infusion rate of 0.2 mg/kg/min produced adequate anaesthesia in these ponies. Cardiovascular changes included a decrease in arterial pressure and card...
Haddad NS, Pedersoli WM, Ravis WR, Fazeli MH, Carson RL.Healthy mature pony mares (n = 6) were given a single dose of gentamicin (5 mg/kg of body weight) IV or IM 8 days apart. Venous blood samples were collected at 0, 5, 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, 30, 36, 40, and 48 hours after IV injection of gentamicin, and at 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, and 30 hours after IM injection of gentamicin. Gentamicin serum concentration was determined by a liquid-phase radioimmunoassay. The combined data of IV and IM treatments were analyzed by a nonlinear least-square...
Barsan WG, Hedges JR, Syverud SA, Dalsey WC.The treatment of cardiovascular collapse and anaphylactic shock is largely empiric. A simple animal model was developed to evaluate the hemodynamic alterations in anaphylaxis. Eight adult New Zealand white rabbits of both sexes were studied. All animals weighed 3.8 kg to 5.3 kg. Sensitization was accomplished with a 2-mL subcutaneous dose of horse serum followed in two days with a 2-mL intravenous (IV) dose. At least 14 days elapsed after the IV dose before a 1-mL challenge dose of horse serum was given. On the day of the challenge dose, a femoral arterial catheter, arterial temperature probe,...
Hunt JM, Gerring EL.Prostaglandin E1 was infused intravenously (25, 50 and 75 ng/kg/min) in three ponies. Changes in gastrointestinal mechanical and electrical activity were recorded from chronically implanted strain-gauge force transducers and electrodes. Dose-dependent responses were obtained: there were significant decreases in electrical spiking activity in the stomach, left large colon and small colon, with a corresponding decrease of activity in the left dorsal colon mechanogram. The small intestine was also affected, showing a decrease in both contraction rate and amplitude, which was more marked in the pr...
Berryhill EH, Knych H, Edman JM, Magdesian KG.The neurokinin-1 (NK) receptor antagonist, maropitant citrate, mitigates nausea and vomiting in dogs and cats. Nausea is poorly understood and likely under-recognized in horses. Use of NK-1 receptor antagonists in horses has not been reported. The purpose of this study was to determine the pharmacokinetic profile of maropitant in seven adult horses after single intravenous (IV; 1 mg/kg) and intragastric (IG; 2 mg/kg) doses. A randomized, crossover design was performed. Serial blood samples were collected after dosing; maropitant concentrations were measured using LC-MS/MS. Pharmacokinetic pa...
Skarda RT, Muir WW.To examine effects of atipamezole on detomidine midsacral subarachnoidally-induced analgesia, cardiovascular and respiratory activity, head ptosis, and position of pelvic limbs in healthy mares. Methods: 10 healthy mares. Methods: Using a randomized, blinded, crossover study design, mares received detomidine (0.03 mg/kg of body weight, diluted in 3 ml of CSF) midsacral subarachnoidally, followed by atipamezole (0.1 mg/kg [test]) or sterile saline (0.9% NaCl) solution (control), i.v. 61 minutes later and saline solution (3 ml, midsacral subarachnoidally) on a separate occasion, at least 2 weeks...
McGrath BM, Scott CJ, Wynn PC, Loy J, Norman ST.Managing the return to regular cyclicity after the winter anestrous period in the mare has been a challenge for the equine breeding industry. Specifically, efforts have been made to shift or shorten the vernal transition period and to have it followed by a predictable first ovulation at the commencement of the breeding season. Intravenous administration of kisspeptin is known to stimulate an LH response in both reproductively active and inactive mares. This study examined the effects of a constant rate infusion (CRI) of kisspeptin on mares during vernal transition. Mares were given a 30 hours...
Jaussaud P, Courtot D, Doron P, Guyot JL.Chronopharmacokinetics of intravenous phenylbutazone in the horse was studied with the aim of antidoping control. Among parameters studied, the single one which seemed to depend on circadian rhythm was the elapsed time between the injection and the plasmatic peak. There was no relationship between the injection time and the both parameters: half-life and time required to reach the forensic level of 4 micrograms/ml. This later, and oxyphenbutazone/phenylbutazone ratio, should depend on individual factors. Therefore, the injection time should not be a main parameter for the phenylbutazone evalua...
Bienert-Zeit A, Gietz C, Staszyk C, Kietzmann M, Stahl J, Ohnesorge B.To monitor concentrations of sulfadimidine in the paranasal sinus mucosa (PSM) of unsedated horses following IV administration of trimethoprim-sulfadimidine via in vivo microdialysis. Methods: 10 healthy adult horses. Methods: Concentric microdialysis probes were implanted into the subepithelial layers of the frontal sinus mucosa of standing sedated horses. Four hours after implantation, trimethoprim-sulfadimidine (30 mg/kg) was administered IV every 24 hours for 2 days; dialysate and plasma samples were collected at intervals during that 48-hour period and analyzed for concentrations of sulfa...
Dudan F, Hirni H.Since 1980 techniques specifically designed to treat human neonatal diseases have also started to be applied to ill or premature equine newborns. These techniques will be described and their application to the most common equine neonatal disorders will be discussed. Such techniques include: post-natal cardiopulmonary resuscitation, exogenous thermal support, administration of broad spectrum antibiotics after diagnostic studies, supplemental oxygen therapy and mechanical ventilation, intravenous fluid and electrolyte therapy, blood component transfusion and total parenteral nutrition.
Moon PF, Snyder JR, Haskins SC, Perron PR, Kramer GC.Conventional fluid resuscitation is unsatisfactory in a small percentage of equine emergency surgical cases because the large volumes of fluids required cannot be given rapidly enough to adequately stabilize the horse. In anesthetized horses, the volume expansion and cardiopulmonary effects of a small volume of highly concentrated hypertonic saline-dextran solution were evaluated as an alternative initial fluid choice. Seven halothane-anesthetized, laterally recumbent, spontaneously ventilating, normovolemic horses were treated with a 25% NaCl-24% dextran 70 solution (HSD) at a dosage of 1.0 m...
Uboh CE, Soma LR, Rudy JA, Morgan E, Mengeringhausen K, Sams R.This study was undertaken to determine the applicability of plasma concentration of furosemide and specific gravity (SG) of urine in regulating the use of furosemide administered 4 hours prior to race time in Exercise-Induced Pulmonary Hemorrhage (EIPH) race horses. Nonbleeders (CTL) and certified bleeders (FUR) actively racing in Illinois (IL) and Pennsylvania (PA) were used in the study. Various doses (less than 250, 250, 300, 350, 400 and 500 mg) were administered either as a single intravenous (IV) dose or as a combination (IV-IM) of IV and intramuscular (IM) administrations 4 hours before...
Hess EK, Reinhart JM, Anderson MJ, Jannasch AS, Taylor SD.Thiamine is a vital co-factor for several anti-inflammatory and antioxidant processes that are critical for mitigation of sepsis-associated inflammation, but pharmacokinetic (PK) analysis has not been reported in horses. We hypothesized that IV thiamine hydrochloride (TH) at increasing dosages would result in corresponding increases in plasma thiamine concentrations without causing adverse effects. A randomized cross-over study was performed in 9 healthy horses that each received TH at 5, 10, and 20 mg/kg IV. Blood was collected immediately prior to drug administration and at several time poi...
Soma LR, Uboh CE, Guan F, Moate P, Luo Y, Teleis D, Li R, Birks EK, Rudy JA, Tsang DS.The pharmacokinetics of clenbuterol (CLB) following a single intravenous (i.v.) and oral (p.o.) administration twice daily for 7 days were investigated in thoroughbred horses. The plasma concentrations of CLB following i.v. administration declined mono-exponentially with a median elimination half-life (t(1/2k)) of 9.2 h, area under the time-concentration curve (AUC) of 12.4 ng.h/mL, and a zero-time concentration of 1.04 ng/mL. Volume of distribution (V(d)) was 1616.0 mL/kg and plasma clearance (Cl) was 120.0 mL/h/kg. The terminal portion of the plasma curve following multiple p.o. administrati...
Knych HK, Steffey EP, Mitchell MM, Casbeer HC.The use of fentanyl is limited in adult horses, in part due to potential for central nervous system excitation. The pharmacokinetics and the plasma concentration-related behavioural actions of fentanyl have not been described for young foals. The goal of the present study was to describe the pharmacokinetics and behavioural effects of fentanyl following administration to the same group of foals at 3 different ages. Experimental study in healthy foals. Fentanyl was administered i.v. (4 μg/kg bwt) to a group of 9 foals on 3 separate occasions at 6–8, 20–22 and 41–42 days of age. Blood sam...
Muir WW, Sams RA, Ashcraft S.The haemodynamic, respiratory and behavioural effects and pharmacokinetics of methocarbamol were studied in eight healthy, adult horses after intravenous (i.v.) and oral administration of large dosages. Heart rate, cardiac output, mean pulmonary arterial blood pressure, systolic, diastolic and mean aortic blood pressure, respiratory rate and arterial blood gases did not change after either i.v. (30 mg/kg bodyweight [bwt]) or oral (50 and 100 mg/kg bwt) dosages of methocarbamol. Mild to moderate depression was observed in five of eight horses administered i.v. methocarbamol, and in all horses a...
La Rosa L, Twele L, Duchateau L, Gasthuys F, Kästner SB, Schauvliege S.A bolus of 50 mg kg MgSO (treatment Mg) or the same volume of saline (treatment S) was infused over 15 minutes in 5 adult healthy horses. T0 was the end of the infusion. Physiological parameters were recorded throughout the study period. Measurements of electrical, thermal, and mechanical nociceptive thresholds were performed at the pelvic limbs at baseline (before T0), and at specific timepoints. Blood samples were taken at fixed timepoints before, during and until 12 hours after the infusion. For statistical analysis, the 95% confidence intervals (CI's) for the differences in nociceptive th...
Cenani A, Brosnan RJ, Madigan S, Knych HK, Madigan JE.Propranolol has been suggested for anxiolysis in horses, but its sedation efficacy and side effects, both when administered alone and in combination with α-adrenoceptor agonists, remain undetermined. This study aimed to document the pharmacokinetics and pharmacodynamics of propranolol, romifidine and their combination. Methods: Randomized, crossover study. Methods: Six adult horses weighing 561 ± 48 kg. Methods: Propranolol (1 mg kg; treatment P), romifidine (0.1 mg kg; treatment R) or their combination (treatment PR) were administered intravenously with a minimum of 1 week between treatment...
Grubb TL, Constable PD, Benson GJ, Foreman JH, Olson WO, Thurmon JC, Tranquilli WJ, Davis LE.To determine the most repeatable method for evaluating right ventricular relaxation rate in horses and to determine and compare effects of isoflurane or halothane with and without the added influence of intravenously administered calcium gluconate on right ventricular relaxation rates in horses. Methods: 6 Thoroughbred horses from 2 to 4 years old. Methods: 6 models (2 for monoexponential decay with zero asymptote, 3 for monoexponential decay with variable asymptote, and 1 for biexponential decay) for determining right ventricular relaxation rate were assessed in conscious and anesthetized hor...
Soraci AL, Mestorino ON, Errecalde JO.The pharmacokinetics and bioavailability of cefoperazone (CPZ) were studied following intravenous (IV) and intramuscular (IM) administration of single doses (30 mg/kg) to horses. Concentrations in serum, urine and synovial fluid samples were measured following IV administration. CPZ concentrations in serum, synovial fluid and spongy bone samples were measured following IM administration. After IV administration a rapid distribution phase (t1/2 (alpha): 4.22 +/- 2.73 min) was followed by a slower elimination phase (t1/2(beta) 0.77 +/- 0.19 h). The apparent volume of distribution was 0.68 +/- 0....
Johnson E, van Heemst J, Benavides J, Gray B.Etizolam is a benzodiazepine analogue that is approved for use in Japan, Italy and India but has recently appeared as a nonapproved product on the illicit drug market in Europe and North America. Etizolam was identified in a crystalline material seized at a Kentucky racetrack, raising concerns that this drug may have been used in racing. The aim of this study was to characterize the metabolism and excretion of etizolam in horses to generate information on its disposition and to incorporate the correct urinary and serum target analytes into anti-doping screening procedures. Etizolam was adminis...
Knych HK, Steffey EP, White AM, McKemie DS.Tramadol is an analgesic agent used in man and a number of veterinary species. The pharmacokinetics and behavioural effects of tramadol and its active metabolite have been described in mature horses, but not in young foals. Objective: To characterise the pharmacokinetics, metabolism and some induced behavioural and physiological responses following i.v. tramadol administration in the same group of foals on 4 different occasions, from a few days after birth to age 43 days. Methods: Experimental. Methods: Tramadol was administered i.v. (3 mg/kg bwt) to a group of 8 foals on 4 separate occasion...
Still J, Serteyn D, van der Merwe CA.Anaesthesia was induced in horses (n = 6) with a mixture of thiopentone and guaiphenesin and maintained by mechanical ventilation with a mixture of oxygen, air and isoflurane. Inspiratory and end-expiratory concentrations of oxygen, carbon dioxide and isoflurane were measured. Electrocardiography was used to evaluate heart rate and rhythm. Mean systemic arterial pressure (SAPm), pulmonary artery pressure (PAPm), right atrial pressure (RAPm) and pulmonary capillary wedge pressure (PCWP) were measured directly. Cardiac output was determined using the thermodilution method. Microcirculation in th...
Abass BT, Weaver BM, Staddon GE, Waterman AW.The pharmacokinetics of thiopentone sodium administered intravenously as a single dose (11 mg/kg) were studied in acepromazine pre-medicated horses and ponies in which anaesthesia was maintained with either halothane (Group 1) or isoflurane (Group 2). The results showed that the disposition kinetics of thiopentone in horses and ponies were best described by a three-compartment open model. In plasma, a very short initial distribution phase in both horses and ponies, half-life 1.4 +/- 1.2 min (mean +/- SD) and 1.3 +/- 0.7 min, respectively, was obtained, which was followed by a second comparativ...
Moore JN, Garner HE, Shapland JE, Roberts MC.The infusion (IV) of prostacyclin (PGI2) into conscious ponies resulted in systemic arterial hypotension and tachycardia. Mean systemic arterial pressure decreased from 103.3 mm of Hg to 88.5 mm of Hg when 125 ng of PGI2/kg/minute was infused, and heart rate increased from 55.0 to 102.0 beats/minute. When 208 ng of PGI2/kg/minute was infused, mean systemic arterial pressure decreased from 103.3 to 78.0 mm of Hg and heart rate increased from 55.0 to 109.3 beats/minute. There were no significant alterations in pulmonary arterial pressure, lactate, PCV, total WBC count, platelet count, serum lact...
Doerffel A, Reinert A, Böttcher D, Winter K, Brehm W, Gittel C.Complications associated with indwelling intravenous catheters vary from minor to severe. Changes in tissue architecture and vein structure may be detectable prior to clinical alterations. The aim of the study was to characterize and compare changes in a catheterized vein and surrounding tissue by clinical and ultrasonographic examination. Microbiological infestation of catheter specimens was assessed. Methods: In this prospective, observational, clinical study 55 horses with an indwelling intravenous catheter have been included. Subsequent to catheter placement, vein and surrounding tissue we...
Reed RA, Epstein KL, Bramski JH, Diehl KA, Ryan CA.To determine the effect of xylazine on intracranial pressure (ICP) in standing compared to isoflurane-anesthetized horses. Methods: Prospective, crossover study design. Methods: University Teaching Hospital. Methods: Six adult horses donated to the University. Horses were determined to be healthy via physical examination, complete blood count, and neurological evaluation. Methods: Horses were anesthetized, maintained on isoflurane in oxygen in left lateral recumbency, and ventilated to normocapnia. Horses were instrumented for intraparenchymal measurement of ICP, invasive blood pressure, pulse...
Zertuche JM, Brown MP, Gronwall R, Merritt K.Pharmacokinetic values for flunixin meglumine (1 mg/kg of body weight) and phenylbutazone (4 mg/kg) dosages were determined after a single IV injection with and without concurrent intragastric administration of probenecid (50 mg/kg) in 6 healthy mares. Significant difference was not apparent in the pharmacokinetic values of flunixin meglumine with and without concurrent probenecid administration. Significant (P less than or equal to 0.05) increase was evident in the 12-hour mean concentration of phenylbutazone (11.45 +/- 1.66 micrograms/ml without probenecid; 14.56 +/- 1.20 micrograms/ml with ...
Kamerling SG, Cravens WM, Bagwell CA.1. Detomidine is a novel veterinary sedative analgesic which is thought to act by stimulation of alpha 2 adrenoreceptors. The present study was undertaken to determine the direction, time course, and dose-response relationship of detomidine on specific autonomic responses in the unanaesthetized horse. 2. Detomidine was administered intravenously to eight adult thoroughbred racehorses at doses of 0.010-0.040 mg kg-1, according to a double-blind Latin square crossover design. Cardiac and respiratory rates, pupil diameter and rectal temperature were monitored for 180 min postinjection. 3. Detomid...
Camargo FC, Robinson NE, Dirikolu L, Berney C, Eberhart S, Derksen FJ, Lehner AF, May J, Hughes C, Tobin T.Trimetoquinol (TMQ) is a very potent and fast acting bronchodilator in horses with heaves. This study assessed the plasma and urinary concentrations of TMQ in horses with heaves following administration via the intravenous (IV, 0.2 microg/kg) and intra-tracheal (IT, 2 microg/kg) routes. TMQ was administered to six horses affected with heaves (RAO - Recurrent Airway Obstruction, used interchangeably) by the above routes and plasma and urine samples collected and stored at -20 degrees C until analyzed. Solid Phase Extraction (SPE) of TMQ was followed by highly sensitive ESI(+)-LC-MS-MS (ElectroS...
Camargo FC, Robinson NE, Berney C, Eberhart S, Baker S, DeTolve P, Derksen FJ, Harkins JD, Lehner AF, Tobin T.Trimetoquinol (TMQ) is a potent beta-adrenoceptor agonist bronchodilator used in human medicine but has not been evaluated for potential use as a therapeutic agent for horses with 'heaves'. Objective: To assess the pharmacodynamics of TMQ in horses with 'heaves' to determine potential therapeutic effects. Methods: Increasing doses of TMQ were administered to horses with 'heaves' by i.v. and intratracheal (i.t.) routes. Doses ranged 0.001-0.2 microg/kg bwt i.v. and 0.01-2 microg/kg bwt i.t. Cardiac and airways effects were assessed by measurement of heart rate (HR) and maximal change in pleural...
Errecalde JO, Landoni MF.The pharmacokinetics of a slow-release theophylline formulation was investigated following intravenous and oral administration at 10 mg/kg in horses. A tricompartmental model was selected to describe the intravenous plasma profile. The elimination half-life (t1/2 beta) was 16.91 +/- 0.93 h, the apparent volume of distribution (Vd) was 1.35 +/- 0.18 L/kg and the body clearance (ClB) was 0.061 +/- 0.009 L kg-1 h. After oral administration the half-life of absorption was 1.24 +/- 0.30 h, and the calculated bioavailability was above 100%. The t1/2 beta after oral administration was 18.51 +/- 1.75 ...
Snow DH, Douglas TA.The absorption characteristics of a new paste preparation of phenylbutazone were studied in ponies and thoroughbreds. The results suggested that at a similar dose rate of 5 mg/kg greater bioavailability results from the paste than from a powder preparation. Delivery of an accurate dosage of the paste was not possible using the multidose applicator. Repeated administration of the paste preparation (5 mg/kg twice daily) indicated that it is more toxic to both ponies and thoroughbreds than a powder preparation. In addition to the toxic manifestations previously reported, a neutropenia developed d...
Luna SP, Taylor PM, Brearley JC.Glucose was infused intravenously into six ponies during halothane anaesthesia, to evaluate its effect on their endocrine response to anaesthesia. The ponies were premedicated with acepromazine, and anaesthesia was induced with thiopentone and maintained with halothane in oxygen for two hours. Glucose was infused to maintain the plasma glucose concentration above 20 mmol/litre. Anaesthesia was associated with hypothermia, a decrease in haematocrit, hypotension, hyperoxaemia, respiratory acidosis and an increase in the plasma concentrations of lactate and arginine vasopressin. The concentration...
