Blood flow in horses refers to the movement of blood through the cardiovascular system, which includes the heart, arteries, veins, and capillaries. This process is essential for delivering oxygen and nutrients to tissues and organs, as well as for removing waste products from the body. Blood flow dynamics in horses are influenced by various factors, including heart rate, blood volume, and vascular resistance. The study of equine blood flow encompasses areas such as circulatory physiology, vascular health, and the impact of exercise on cardiovascular function. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of blood flow in equine health and performance.
Williams KJ, Robinson NE, Defeijter-Rupp H, Millerick-May M, Stack A, Hauptman J, Derksen FJ.Exercise-induced pulmonary hemorrhage (EIPH), which has been reported in humans and a variety of domestic animals following strenuous exercise, is most often documented in racehorses. Remodeling of pulmonary veins (VR) in equine EIPH was recently described, suggesting that it contributes to the pathogenesis of the disease. The cause of VR is unknown. We tested the hypothesis that the development of VR follows pulmonary blood flow distribution, preferentially occurring in the caudodorsal lung region. Furthermore, we hypothesized that VR underpins development of the other lesions of EIPH patholo...
Celeste CJ, Deschesne K, Riley CB, Theoret CL.To map skin temperature kinetics, and by extension skin blood flow throughout normal or abnormal repair of full-thickness cutaneous wounds created on the horse body and limb, using infrared thermography. Methods: Experimental. Methods: Standardbreds (n = 6), aged 3-4 years. Methods: Three cutaneous wounds were created on the dorsolateral surface of each metacarpus and on the lateral thoracic wall. Thoracic skin wounds and those on 1 randomly chosen forelimb healed by second intention without a bandage, whereas contralateral limb wounds were bandaged to induce formation of exuberant granulation...
Ousey JC, Kölling M, Newton R, Wright M, Allen WR.Aged mares with endometrosis suffer higher rates of pregnancy loss than young mares, due to poor placental development. Reduced uterine blood supply may be one contributory factor. Objective: To measure uterine artery (UA) blood flow and other Doppler indices throughout pregnancy and compare placental and foal development in young mares and aged mares. Methods: Thoroughbred mares were grouped according to age and endometrial biopsy score: 1) 6 young mares (mean age 7.3 years, Category ); 2) 6 aged mares (mean age 18.3 years, Category II). Vascular pathology was nil or mild except in one aged m...
Douthit TL, Bormann JM, Gradert KC, Lomas LW, DeWitt SF, Kouba JM.This experiment was conducted to evaluate if consumption of endophyte-infected fescue alters digital circulation in the distal thoracic limb of the horse and to assess if soundness of the hooves of horses is affected by consumption of endophyte-infected fescue. Twelve American Quarter Horses (mean initial BW 459 ± 31 kg), 6 mares and 6 geldings, were used in this 90-d study that comprised high-endophyte (E+) and low-endophyte (E-) treatment groups. Fescue seed was integrated into the E+ diet at a rate sufficient to bring total ergovaline to 200 μg/kg, and endophyte-free fescue seed was incor...
Witt MC, Bollwein H, Probst J, Baackmann C, Squires EL, Sieme H.The aim of the present study was to investigate the effects of a gonadotropin treatment to induce superovulation on ovarian and uterine blood flow and its relationship with steroid hormone levels and ovarian response in mares, using color Doppler sonography. Each of six mares were examined sonographically in five cycles for 3 d (t1 to t3) during the follicular development phase (FDP) beginning at a follicle size of ≥ 22 mm, and for 4 d (D-4 to D-1; D0 = Ovulation) in the preovulatory phase (POP). After each examination, total estrogens (E(tot)) and progesterone (P(4)) levels were determined ...
Bailey CS, Sper RB, Schewmaker JL, Buchanan CN, Beachler TM, Pozor MA, Whitacre MD.The objective of this study was to use Doppler ultrasound technology to determine whether pentoxifylline administration increased uterine blood flow in normal pregnant pony mares. Thirteen pregnant pony mares between 18 and 190 d of gestation (mean ± SEM, 101 ± 55) were utilized for the study during two trial periods. In each trial, pentoxifylline (17 mg/kg by mouth every 12h, diluted in syrup) was administered to half of the mares for 3 d, while the other mares were treated with syrup only. Doppler measurements were obtained from the right and left uterine arteries from each mare for 2 d pr...
Brosnan RJ, Steffey EP, LeCouteur RA, Esteller-Vico A, Vaughan B, Liu IK.To test a hypothesis predicting that isoflurane would interfere with cerebrovascular autoregulation in horses and to evaluate whether increased mean arterial blood pressure (MAP) would increase cerebral blood flow and intracranial pressure (ICP) during isoflurane anesthesia. Methods: 6 healthy adult horses. Methods: Horses were anesthetized with isoflurane at a constant end-tidal concentration sufficient to maintain MAP at 60 mm Hg. The facial, carotid, and dorsal metatarsal arteries were catheterized for blood sample collection and pressure measurements. A sub-arachnoid transducer was used to...
Brosnan RJ, Steffey EP, Esteller-Vico A, Vaughan B, Liu IK.Digital perfusion pressure (DPP) equals mean arterial pressure (MAP) at the hoof coronet minus digital interstitial pressure (DIP) within the hoof. To test whether lamellar blood flow (LBF) changes proportionately to DPP, anesthesia was induced and maintained with isoflurane in six horses to target a MAP of 60 mmHg. Arterial, venous, and hoof interstitial pressures were measured in each pelvic limb. LBF was measured using fluorescent microspheres during dobutamine infusions targeting either 60 (low), 80 (medium), or 100 (high) mmHg MAP. Following euthanasia, hoof lamina was collected for micro...
Guvenal T, Durna A, Erden O, Guvenal F, Cetin M, Cetin A.The purpose of this study was to compare the effects of different postmenopausal hormone therapy regimens, namely conjugated equine estrogens (CEE), CEE plus medroxyprogesterone acetate (MPA), tibolone, and raloxifene on cerebral blood flow and cognitive functions. Methods: A total of 64 healthy postmenopausal women admitted to the Department of Obstetrics and Gynecology, Cumhuriyet University, Turkey were included in this study. Patients were divided into five groups with respect to the treatment protocols: CEE 0.625 mg/day (n=13); CEE 0.625 mg/day + MPA 2.5 mg/day (n=14); tibolone 2.5 mg/day...
Araujo RR, Ginther OJ.To assess the vascular effects of detomidine and xylazine in pony mares and heifers, respectively, as determined in a major artery and by extent of vascular perfusion of reproductive organs. Methods: 10 pony mares and 10 Holstein heifers. Methods: Pony mares were assigned to receive physiologic saline (0.9% NaCl) solution (n = 5) or detomidine (3.0 mg/mare, IV; 5). Heifers were assigned to receive saline solution (5) or xylazine (14 mg/heifer, IM; 5). Color Doppler ultrasonographic examinations were performed immediately before and 10 minutes after administration of saline solution or sedative...
Ginther OJ, Rodrigues BL, Ferreira JC, Araujo RR, Beg MA.Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL(-1). Comparisons were made among preluteolysis, luteolysis, and postluteolysis. Greater prostaglandin F2alpha activity (mean PGFM concentra...
Brosnan RJ, Esteller-Vico A, Steffey EP, LeCouteur RA, Liu IK, Vaughan B.To test the hypothesis that head-down positioning in anesthetized horses increases intracranial pressure (ICP) and decreases cerebral and spinal cord blood flows. Methods: 6 adult horses. Methods: For each horse, anesthesia was induced with ketamine hydrochloride and xylazine hydrochloride and maintained with 1.57% isoflurane in oxygen. Once in right lateral recumbency, horses were ventilated to maintain normocapnia. An ICP transducer was placed in the subarachnoid space, and catheters were placed in the left cardiac ventricle and in multiple vessels. Blood flow measurements were made by use o...
Wongaumnuaykul S, Siedler C, Schobesberger H, Stanek C.The aim of this study was to evaluate the use of Doppler ultrasonography to monitor vascular blood flow dynamics in defined diseases of the equine digit in a noninvasive way. Doppler sonography was used to evaluate medial digital artery blood flow in eight horses with septic pododermatitis and four horses with laminitis in comparison with 10 horses of a control group. Doppler sonographic measurement and lameness examinations were performed in lame horses before treatment (day 0) and at 3, 6, and 9 days following treatment. Before treatment, blood flow velocities, arterial diameter, and flow vo...
Gilhooly MH, Eades SC, Stokes AM, Moore RM.To measure and compare palmar digital venous plasma nitric oxide (NO) concentrations and digital arterial blood flow after application of topical nitroglycerine (NTG). Methods: Experimental study. Methods: Healthy adult horses (n=8). Methods: Digital blood flow was measured by an ultrasonic Doppler flow probe surgically implanted around the medial palmar digital artery. Blood was collected from a catheter placed in the medial palmar digital vein for quantification of NO. NTG patches, NTG ointment or control patches were placed over the palmar digital vessels at the level of the fetlock. Two ho...
Raisis AL.The objective of this review was to describe the methodology and limitations of techniques that have been used to measure skeletal muscle blood flow in anaesthetized horses. Methods: Pubmed, personal files. Conclusions: Numerous techniques have been used in horses to study skeletal muscle blood flow during anaesthesia and after the administration of vasoactive agents. Of the available techniques, blood flow measurements are limited to either microvascular flow (radioactive xenon, laser Doppler flowmetry) or total blood flow (radioactive microspheres, electromagnetic flowmetry, Doppler ultrason...
Solano M, Welcome J, Johnson K.Horses undergoing skeletal scintigraphy can have decreased radiopharmaceutical bone uptake in the limbs. This reduces the diagnostic value of the scan. The aim of the present study was to measure the changes in count density caused by vasodilatation and increased blood flow associated with intravenous injection of acepromazine during bone scintigraphy in normal horses. A three-phase bone scan was performed twice in 11 adult horses to study the effects of acepromazine on the count density of the resultant scintigrams. With acepromazine, there was a statistically significant mean difference of 1...
Schwarzwald CC, Bonagura JD, Luis-Fuentes V.Quinidine is effective for treatment of atrial fibrillation (AF) in horses, but often accelerates ventricular response rate. Diltiazem effectively controls heart rate response to AF in other species. This investigation determined the effects of diltiazem on cardiac rate and rhythm, left ventricular (LV) function, central hemodynamics, and peripheral blood flow in normal, standing, nonsedated horses. A dose-finding study was performed. Afterward, 8 healthy horses were treated with diltiazem IV every 30 minutes to achieve cumulative dosages of 0 (saline control), 1, 1.5, and 2 mg/kg. Plasma dilt...
Pietra M, Guglielmini C, Nardi S, Gandini G, Cipone M.To describe the pulsed-wave Doppler tracing of the equine lateral palmar digital artery and its modification in relation to standardized changes in posture. Methods: 17 healthy Saddlebred horses. Methods: Pulsed-wave Doppler examinations of left and right lateral palmar digital arteries of the horses were performed. The baseline examination was performed on each forelimb while horses were standing squarely with the body weight equally distributed among the 4 limbs (BED position). For each forelimb, the examination was repeated during 3 standardized modifications of the horse's posture (non-wei...
Acosta TJ, Gastal EL, Gastal MO, Beg MA, Ginther OJ.Diameter deviation during a follicular wave is characterized by the continued growth of the developing dominant follicle and reduced growth and regression of the subordinate follicles. This study considered the hypothesis that reduced blood flow in the future largest subordinate follicle precedes the beginning of diameter deviation. The hypothesis was tested by quantifying the daily changes in blood-flow velocities and blood-flow area within the wall of follicles before and during diameter deviation in mares (n = 7). The blood-flow end points were quantified daily by transrectal color Doppler ...
Bollwein H, Kolberg B, Stolla R.In recent years, a positive relationship between genital perfusion and fertility has been established; in species other than horses, uterine and ovarian perfusion was improved by exogenous estrogen but impaired by exogenous progestin. The goal of the present study was to investigate the effect of exogenous estrogen and progestin on uterine and ovarian blood flow in cycling mares. Five Trotter mares were examined daily during three estrous cycles. Mares were given no treatment, altrenogest (0.044 mg/kg BW) orally from Day 0 (ovulation) to Day 14 and estradiol benzoate (5mg i.m.) on Days 0, 5, a...
Bollwein H, Weber F, Woschée I, Stolla R.Transrectal color Doppler sonography was used to investigate uterine and umbilical blood flow during pregnancy (duration, 46-48 weeks) in four mares. The resistance index (RI) and blood flow volume (VOL) of the uterine arteries ipsilateral and contralateral to the conceptus, and the presence of an early diastolic notch in the Doppler wave, were evaluated every 4 week throughout pregnancy. Fetal blood flow was calculated semiquantitatively every 2 week (from 20 to 40 weeks), using the RI of the umbilical arteries. During the entire period of investigation, there were no significant individual v...
Bollwein H, Mayer R, Stolla R.Transrectal color Doppler sonography was used for the noninvasive investigation of uterine blood flow in five mares. Both the left and right uterine arteries were scanned to obtain blood flow velocity waveforms during two consecutive estrous cycles and two early pregnancies in each mare. Blood flow was expressed as the time-averaged maximum velocity (TAMV) and the resistance index (RI). In all pregnancies the embryonic vesicle could be detected for the first time on Day 11 (day of ovulation: Day 0). No differences in mean TAMV and RI values of both uterine arteries were observed in comparison ...
Bollwein H, Sowade C, Stolla R.Transrectal color Doppler sonography was used to evaluate the effect of intrauterine infusion of skim milk semen extender, seminal plasma and raw semen on the endometrium and blood flow in the uterine and ovarian arteries in mares. Six Trotter mares (mean age: 12 years) were examined during estrus in three cycles. Each mare received an intrauterine infusion of 20 ml of skim milk semen extender, seminal plasma or raw semen during estrus in one of three cycles. Blood flow measurements in both uterine and ovarian arteries and the determination of intrauterine fluid via sonography were performed b...
Hoffmann KL, Wood AK, Griffiths KA, Evans DL, Gill RW, Kirby AC.In six normal adult horses, pulsed-wave Doppler sonographic inspections were made of the left and right lateral palmar proper digital artery (LPPDA) of each thoracic limb. Using a two-period, crossover design with repeated measures, each LPPDA was inspected on four occasions throughout the day over a 7 hour period and, on each occasion, with the limb weight bearing and non-weight bearing. In comparison with the observations made during weight bearing, there were significant increases (P<0.001) in blood-flow velocities when the limb was non-weight bearing. There was no relationship between b...
Tetens J, Eades SC, Hosgood G, Koch CE, Moore RM.To characterize alterations in systemic and local colonic hemodynamic variables associated with IV infusion of ATP-MgCl2 in healthy anesthetized horses. Methods: 12 adult horses. Methods: Six horses were given ATP-MgCl2, IV, beginning at a rate of 0.1 mg of ATP/kg of body weight/min with incremental increases until a rate of 1.0 mg/kg/min was achieved. The remaining 6 horses were given an equivalent volume of saline (0.9% NaCl) solution over the same time period. Colonic and systemic hemodynamic variables and colonic plasma nitric oxide (NO) concentrations were determined before, during, and a...
Hoffmann KL, Wood AK, Griffiths KA, Evans DL, Gill RW, Kirby AC.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. ...
Raisis AL, Young LE, Blissitt KJ, Walsh K, Meire HB, Taylor PM, Lekeux P.To evaluate the hemodynamic effects of dobutamine hydrochloride (0.5 microg/kg of body weight/min) in halothane-anesthetized horses. Methods: 6 adult Thoroughbred horses. Methods: Anesthesia was induced by use of romifidine (100 microg/kg) and ketamine (2.2 mg/kg), IV. Anesthesia was maintained by halothane (end-tidal concentration 0.9 to 1.0%). Aortic, left ventricular, and right atrial pressures were measured, using catheter-mounted strain gauge transducers. Cardiac output (CO), velocity time integral, maximal aortic blood flow velocity and acceleration, and left ventricular preejection peri...
Steyn PF, Ramey DW, Kirschvink J, Uhrig J.To determine the effect of a static magnetic field on relative blood flow to the metacarpus of horses. Methods: Randomized controlled clinical trial. Methods: 6 healthy adult horses. Methods: Red blood cells were radiolabeled in vivo by administration of technetium Tc 99m (pyro- and trimeta-) phosphates, and scintigraphic images were obtained 30 minutes later. A magnetic wrap that emitted a static magnetic field was applied to 1 metacarpus and a control wrap was applied to the contralateral metacarpus. Forty-eight hours later, the wraps were removed, and scintigraphy was repeated. Relative per...
Adair HS, Goble DO, Schmidhammer JL, Shires GM.To measure changes in laminar microvascular blood flow (LMBF) over time in healthy horses and horses in the prodromal stage of black walnut-induced laminitis and to determine the effects of glyceryl trinitrate application on LMBF in horses with acute laminitis. Methods: 10 healthy adult horses. Methods: Laser Doppler flowmetry was used to measure LMBF Baseline measurements were obtained, horses were given deionized water via a nasogastric tube, and measurements were obtained hourly for 12 hours. Twenty-four hours later, baseline measurements were again obtained, and horses were given black wal...
Bollwein H, Mayer R, Stolla R.Transrectal color Doppler sonography was used for the noninvasive investigation of uterine blood flow in five mares. Both the left and right uterine arteries were scanned to obtain blood flow velocity waveforms during two consecutive estrous cycles and two early pregnancies in each mare. Blood flow was expressed as the time-averaged maximum velocity (TAMV) and the resistance index (RI). In all pregnancies the embryonic vesicle could be detected for the first time on Day 11 (day of ovulation: Day 0). No differences in mean TAMV and RI values of both uterine arteries were observed in comparison ...
Elliott AR, Steffey EP, Jarvis KA, Marshall BE.The hypoxic pulmonary vasoconstrictor response to unilateral hypoxia was analyzed in pentobarbital anesthetized dogs (n = 5), miniature swine (n = 5), and ponies (n = 5). The left and right lungs (LL, RL) were separately ventilated with the LL exposed to inspired oxygen concentrations (CIO2) of 100%, 12%, 8% or 4%, while the RL always received a CIO2 = 100%. Pulmonary blood flow distribution was measured using 15 microns radioactive microspheres. LL PAO2, and percent pulmonary blood flow diversion (%FD) were calculated at each CIO2. At CIO2 of 4% there were significant differences (P greater t...
McConaghy FF, Hodgson DR, Rose RJ, Hales JR.Radioactive microspheres were used to measure cardiac output and blood flow to most major tissues in 4 ponies at rest in thermoneutral (16 degrees C/60% RH) and mildly hot (41 degrees C/34% RH) environments. In response to heat stress there were increases in cardiac output (2-fold), respiratory frequency (5-fold), blood flow to the skin of the body (3-fold), and limbs (50%), respiratory muscles (2-fold) and the upper respiratory tract (3-fold). Ponies were able to maintain body temperature in the hot environment by increasing blood flow to the tissues involved in heat dissipation, while blood ...
Manohar M, Bisgard GE, Bullard V, Will JA, Anderson D, Rankin JH.Hemodynamics, myocardial function, and regional myocardial blood flow (MBF) were measured in 6 closed-chest ponies anesthetized with ketamine hydrochloride before (control) and after creation of acute right ventricular systolic hypertension (RVSH) during normoxia and isocapnic hypoxia. The right ventricular (RV) systolic pressure during each RVSH approached 90 mmHg. There were significant alterations in the pattern of total ventricular MBG distribution in favor of the RV. Because RV myocardium received proportionate increments to its endocardium as well as epicardium, it is concluded that auto...
Ginther OJ, Rodrigues BL, Ferreira JC, Araujo RR, Beg MA.Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL(-1). Comparisons were made among preluteolysis, luteolysis, and postluteolysis. Greater prostaglandin F2alpha activity (mean PGFM concentra...
Esteller-Vico A, Liu IK, Vaughan B, Steffey EP, Brosnan RJ.In the uterus of the mare, data obtained using transrectal Doppler ultrasonography indicate that uterine blood flow (UBF) is dynamic and changes throughout the estrous cycle. Degenerative lesions in the uterus are associated with subfertility and infertility. Among these lesions, vascular elastosis has been reported in aged, multiparous, and infertile mares. Angiosis of the uterine vasculature could potentially compromise UBF. The objectives of this experiment are to determine levels of UBF and perfusion of reproductively healthy mares and compare them to levels of subfertile/infertile mares a...
Pelletier N, Robinson NE, Kaiser L, Derksen FJ.We investigated regional differences of in vitro responses of pulmonary arteries (6-mm OD) from the dorsocaudal (top) and cranioventral (bottom) lung regions to endothelium-dependent vasodilators (methacholine, bradykinin, and calcium ionophore A-23187). Methacholine relaxed endothelium-intact top vessels; however, in bottom vessels, a small relaxation preceded a profound contraction. In top vessels, removal of endothelial cells converted relaxation to contraction, and in bottom vessels it abolished relaxation and enhanced contraction. Bradykinin and A-23187 were more potent and caused greater...
Turner TA, Fessler JF, Lamp M, Pearce JA, Geddes LA.The distal forelimbs of 10 clinically normal horses with hair clipped on 1 limb were thermographically scanned before and after exercise. The thermal patterns, temperature distribution, and temperature changes after exercise were determined and compared with those of 8 horses with podotrochlosis. Clipping the hair did not cause changes in the thermal patterns, but the clipped limbs were warmer than the unclipped limbs. The temperature of the limbs of horses with podotrochlosis did not increase as much after exercise as did the limbs of normal horses. The failure of skin temperature increase co...
Zaha C, Schuszler L, Dascalu R, Nistor P, Florea T, Imre K, Rujescu C, Sicoe B, Igna C.Horses with palmar foot pain do not show a typical increase in temperature in the palmar aspect of the hoof and heel due to low blood flow. The objectives of the current study were to determine the changes and differences in the thermographic pattern of the sole surface in horses with unilateral palmar foot pain and non-lame horses before and after training. We hypothesized that the thermal pattern and the local temperature of the frog area and toe area would be similar, with an increased local temperature after training in both lame and non-lame horses. A pilot study was conducted to investig...
Steyn PF, Ramey DW, Kirschvink J, Uhrig J.To determine the effect of a static magnetic field on relative blood flow to the metacarpus of horses. Methods: Randomized controlled clinical trial. Methods: 6 healthy adult horses. Methods: Red blood cells were radiolabeled in vivo by administration of technetium Tc 99m (pyro- and trimeta-) phosphates, and scintigraphic images were obtained 30 minutes later. A magnetic wrap that emitted a static magnetic field was applied to 1 metacarpus and a control wrap was applied to the contralateral metacarpus. Forty-eight hours later, the wraps were removed, and scintigraphy was repeated. Relative per...
Raisis AL, Young LE, Blissitt KJ, Walsh K, Meire HB, Taylor PM, Lekeux P.To evaluate the hemodynamic effects of dobutamine hydrochloride (0.5 microg/kg of body weight/min) in halothane-anesthetized horses. Methods: 6 adult Thoroughbred horses. Methods: Anesthesia was induced by use of romifidine (100 microg/kg) and ketamine (2.2 mg/kg), IV. Anesthesia was maintained by halothane (end-tidal concentration 0.9 to 1.0%). Aortic, left ventricular, and right atrial pressures were measured, using catheter-mounted strain gauge transducers. Cardiac output (CO), velocity time integral, maximal aortic blood flow velocity and acceleration, and left ventricular preejection peri...
Serteyn D, Mottart E, Michaux C, Micheels J, Philippart C, Lavergne L, Guillon C, Lamy M.Muscular microcirculation was studied in seven halothane anaesthetised horses in lateral recumbency using a laser Doppler flowmeter. A significant difference between the dependent and the uppermost triceps brachii was recorded. In the dependent muscles, microflow at first decreased and then increased up to the starting value. In the uppermost muscles, a significant rise of the microflow was measured.
Ousey JC, Kölling M, Newton R, Wright M, Allen WR.Aged mares with endometrosis suffer higher rates of pregnancy loss than young mares, due to poor placental development. Reduced uterine blood supply may be one contributory factor. Objective: To measure uterine artery (UA) blood flow and other Doppler indices throughout pregnancy and compare placental and foal development in young mares and aged mares. Methods: Thoroughbred mares were grouped according to age and endometrial biopsy score: 1) 6 young mares (mean age 7.3 years, Category ); 2) 6 aged mares (mean age 18.3 years, Category II). Vascular pathology was nil or mild except in one aged m...
Blohm KO, Tichy A, Nell B.To determine efficacy of contrast-enhanced ultrasonography (CEUS) using different sulfur hexafluoride (SF6) doses to assess blood flow and perfusion in equine eyes and to evaluate safety of SF6 in horses. Methods: Ocular B-mode and contrast-enhanced ultrasonography were performed bilaterally in nine sedated university-owned horses. Intravenous SonoVue® bolus injections of 5, 10, 15, 20, 25, and 30 mL were administered for 2/18, 5/18, 6/18, 3/18, 1/18, and 1/18 eyes, respectively. Doses were increased based on ascending bodyweight. Each eye within one horse was examined utilizing a different ...
Cochard T, Toal RL, Saxton AM.To determine blood flow velocities and indices from spectral waveforms obtained by use of Doppler ultrasonography of thoracic limb arteries of horses and to assess interobserver and patient variability associated with the technique. Methods: 9 clinically normal adult horses. Methods: Left thoracic limb arteries of 8 nonsedated horses were examined at 5 sites by use of pulsed-wave Doppler ultrasonography to determine a range of values for peak systolic, end diastolic, and mean velocities and resistive and pulsatility indices. Interobserver and patient variabilities were determined by 2 operator...
Schier MF, Raisis AL, Secombe CJ, Hosgood G, Musk GC, Lester GD.OBJECTIVE To determine the effects of acepromazine maleate premedication on cardiovascular function before and after infusion of dobutamine hydrochloride for 30 minutes in isoflurane-anesthetized horses. ANIMALS 6 healthy adult horses. PROCEDURES Each horse was anesthetized once following premedication with acepromazine (0.02 mg/kg, IV) administered 30 minutes prior to anesthetic induction (ACP+ treatment) and once without premedication (ACP- treatment). Anesthesia was induced with IV administration of xylazine hydrochloride (0.8 mg/kg), ketamine hydrochloride (2.2 mg/kg), and diazepam (0.08 m...
Goetz TE, Manohar M, Nganwa D, Gustafson R.The effects of 1.1, 1.5 and 1.8 MAC (minimum alveolar concentration) isoflurane-02 anaesthesia on skeletal muscle blood flow, 02 delivery and vascular resistance were studied in the non-dependent region of seven healthy normothermic, isocapnoeic ponies. Muscle blood flow was determined with 15 microns diameter radionuclide labelled microspheres that were injected into the left ventricle. Muscle blood flow during anaesthesia was compared to unanaesthetised (control) measurements. Isoflurane administration caused a dose dependent decrease in mean aortic pressure, and skeletal muscle (temporalis,...
Nerem RM, Rumberger JA, Gross DR, Muir WW, Geiger GL.Coronary velocity measurements have been carried out in anaesthetized, open-chest horses using a constant-temperature, hot-film anemometer system. L-shaped needle probes inserted by direct vessel puncture have been used to measure velocity profiles in the left common, left anterior descending (LAD), and left circumflex coronary arteries. The flow conditions were characterized by peak Reynolds numbers from approximately 200 to 1500 and values of the unsteadiness parameter from 3 to 10. These measurements indicate that in the left common coronary artery the profile is in general skewed towards t...
Manohar M.1. Transmural distribution of myocardial blood flow was studied using 15 micron diameter radionuclide-labelled microspheres in six normal ponies and nine splenectomized ponies at rest, and during maximal exercise performed without as well as with adenosine infusion (3 microM kg-1 min-1). The splenectomized ponies were also studied during submaximal exercise performed at 75% of the workload. 2. Maximal exertion in normal ponies increased heart rate (348%), mean arterial blood pressure (40.9%), rate-pressure product (563%), arterial O2 content (43.2%), and mean pulmonary artery pressure (247%). ...
Blissitt KJ, Young LE, Jones RS, Darke PG, Utting J.Measurement of cardiac output by Doppler echocardiography were compared to simultaneous measurements by thermodilution in 9 conscious horses. In the Doppler technique, mean blood flow velocities for estimation of cardiac output were recorded from the aorta and pulmonary artery. The flow area of each vessel was calculated from the vessel diameter, measured from a 2-dimensional ultrasound image. Differences in the site and method of measuring the vessel diameter altered the estimation of cardiac output by the Doppler method. Cardiac output was modified by the i.v. infusion of 4 micrograms/kg bwt...
Reef VB, Lalezari K, De Boo J, van der Belt AJ, Spencer PA, Dik KJ.Pulsed-wave Doppler echocardiography was performed on 30 clinically normal 1- to 6-year-old racing Standardbreds. There were 13 females, 13 geldings, and 4 stallions. Cardiac disease was not detected with M-mode, 2-dimensional real-time or pulsed-wave Doppler echocardiography. Normal flow velocities for right and left atrial outflow, right and left ventricular outflow, the aorta, and pulmonary artery were determined. Peak flow velocities for right and left atrial outflow occurred during the rapid filling phase and were higher toward the mitral valve (mean, 0.70 +/- 0.24 m/s) than toward the tr...
Hoffmann KL, Wood AK, Griffiths KA, Evans DL, Gill RW, Kirby AC.In six normal adult horses, pulsed-wave Doppler sonographic inspections were made of the left and right lateral palmar proper digital artery (LPPDA) of each thoracic limb. Using a two-period, crossover design with repeated measures, each LPPDA was inspected on four occasions throughout the day over a 7 hour period and, on each occasion, with the limb weight bearing and non-weight bearing. In comparison with the observations made during weight bearing, there were significant increases (P<0.001) in blood-flow velocities when the limb was non-weight bearing. There was no relationship between b...
Raisis AL, Young LE, Taylor PM, Walsh KP, Lekeux P.To use Doppler ultrasonography and single-fiber laser Doppler flowmetry (LDF) to evaluate blood flow in the dependent and nondependent hind limbs of anesthetized horses and to evaluate changes in femoral arterial blood flow and microvascular skeletal muscle perfusion in response to administration of phenylephrine hydrochloride or dobutamine hydrochloride. Methods: 6 healthy adult horses. Methods: Horses were anesthetized and positioned in left lateral recumbency. Doppler ultrasonography was used to measure velocity and volumetric flow in the femoral vessels. Single-fiber LDF was used to measur...
Wongaumnuaykul S, Siedler C, Schobesberger H, Stanek C.The aim of this study was to evaluate the use of Doppler ultrasonography to monitor vascular blood flow dynamics in defined diseases of the equine digit in a noninvasive way. Doppler sonography was used to evaluate medial digital artery blood flow in eight horses with septic pododermatitis and four horses with laminitis in comparison with 10 horses of a control group. Doppler sonographic measurement and lameness examinations were performed in lame horses before treatment (day 0) and at 3, 6, and 9 days following treatment. Before treatment, blood flow velocities, arterial diameter, and flow vo...
Manohar M, Goetz TE.Blood flow to the brain, kidneys, adrenal glands, pancreas, and small intestine was studied in 8 healthy ponies while awake (control) and during 1.0, 1.5, and 2.0 minimal alveolar concentrations (MAC) of anesthesia produced, using halothane vaporized in oxygen. During the anesthesia steps, intermittent positive-pressure ventilation was used to ensure isocapnia. Organ blood flow was determined with 15-micron (diameter) radionuclide-labeled microspheres, after allowing 30 minutes of equilibration at each of the 3 preestablished end-tidal halothane concentrations. The sequence of 1.0, 1.5, and 2....
Loughran CM, Raisis AL, Hosgood G, Secombe CJ, Lester GD.Cardiac output does not always increase with dobutamine administration in anaesthetised horses and information on peripheral perfusion is lacking. Objective: To determine the effect of intravenous (i.v.) dobutamine infusion with and without a concurrent 20 mL/kg bodyweight (bwt) bolus of crystalloid fluids on the cardiovascular function of acepromazine premedicated, hypotensive, isoflurane-anaesthetised horses. Methods: Randomised, cross-over experiment. Methods: A total of 6 horses aged 5-13 years, weighing 464-578 kg were premedicated with acepromazine 0.02 mg/kg bwt and then sedated with xy...
Bollwein H, Kolberg B, Stolla R.In recent years, a positive relationship between genital perfusion and fertility has been established; in species other than horses, uterine and ovarian perfusion was improved by exogenous estrogen but impaired by exogenous progestin. The goal of the present study was to investigate the effect of exogenous estrogen and progestin on uterine and ovarian blood flow in cycling mares. Five Trotter mares were examined daily during three estrous cycles. Mares were given no treatment, altrenogest (0.044 mg/kg BW) orally from Day 0 (ovulation) to Day 14 and estradiol benzoate (5mg i.m.) on Days 0, 5, a...
Guvenal T, Durna A, Erden O, Guvenal F, Cetin M, Cetin A.The purpose of this study was to compare the effects of different postmenopausal hormone therapy regimens, namely conjugated equine estrogens (CEE), CEE plus medroxyprogesterone acetate (MPA), tibolone, and raloxifene on cerebral blood flow and cognitive functions. Methods: A total of 64 healthy postmenopausal women admitted to the Department of Obstetrics and Gynecology, Cumhuriyet University, Turkey were included in this study. Patients were divided into five groups with respect to the treatment protocols: CEE 0.625 mg/day (n=13); CEE 0.625 mg/day + MPA 2.5 mg/day (n=14); tibolone 2.5 mg/day...
Hunt RJ, Brandon CI, McCann ME.Palmar digital arterial blood flow was measured in 6 conscious, standing horses, using surgically placed perivascular ultrasonic flow probes. The effects of 2 dosages of xylazine (0.55 and 1.1 mg/kg of body weight) and of 3 dosages of acetylpromazine (0.01, 0.02, and 0.04 mg/kg), as well as the effect of vertical load, on digital blood flow were evaluated. Intravenous administration of xylazine induced a significant (P < 0.05), transient decrease in digital blood flow. Intravenous administration of acetylpromazine induced a significant (P < 0.05), prolonged increase in digital blood flow...
Bailey CS, Sper RB, Schewmaker JL, Buchanan CN, Beachler TM, Pozor MA, Whitacre MD.The objective of this study was to use Doppler ultrasound technology to determine whether pentoxifylline administration increased uterine blood flow in normal pregnant pony mares. Thirteen pregnant pony mares between 18 and 190 d of gestation (mean ± SEM, 101 ± 55) were utilized for the study during two trial periods. In each trial, pentoxifylline (17 mg/kg by mouth every 12h, diluted in syrup) was administered to half of the mares for 3 d, while the other mares were treated with syrup only. Doppler measurements were obtained from the right and left uterine arteries from each mare for 2 d pr...
