Arteries in horses are blood vessels responsible for carrying oxygenated blood away from the heart to various tissues and organs throughout the body. These vessels are integral to the circulatory system, facilitating the delivery of essential nutrients and oxygen to maintain cellular function and overall health. The structure of equine arteries includes a thick muscular wall that accommodates the high pressure of blood flow, allowing for efficient transport. Research on equine arteries often focuses on their anatomical characteristics, physiological functions, and potential disorders that may affect them, such as atherosclerosis or aneurysms. This page compiles peer-reviewed research studies and scholarly articles that examine the anatomy, physiology, and pathophysiology of arteries in horses.
Vera L, De Clercq D, Van Steenkiste G, Decloedt A, Chiers K, van Loon G.Aortic rupture is more common in Friesians compared to Warmbloods, which might be related to differences in arterial wall composition and, as such, arterial wall stiffness (AWS). Currently, nothing is known about differences in AWS between these breeds. Objective: Comparison of AWS parameters and noninvasive blood pressure between Friesians and Warmbloods. Methods: One hundred one healthy Friesians and 101 age-matched healthy Warmbloods. Methods: Two-dimensional and pulsed-wave Doppler ultrasound examination was performed of the aorta, common carotid artery, and external iliac artery to define...
The renal resistive index (RRI) is used as a measurement of downstream resistance in arteries. The aim of this study was to assess the RRI of the arcuate arteries by pulsed-wave Doppler ultrasonography in healthy conscious horses and donkeys, and to verify any differences related to age, breed, bodyweight (BW) or body condition (BCS). Thirty-three healthy conscious horses and nine donkeys had their systolic and diastolic flow velocities at the level of the arcuate arteries estimated by pulsed-wave Doppler ultrasound, and the RRI was calculated. The relationship of RRI with age, breed (Trotters...
Sievers H, Hiebl B, Hünigen H, Hirschberg RM.Blood supply is an important factor for the normal function of the equine hoof, but earlier studies present conflicting data on functional characteristics of its angioarchitecture. Objective: Emphasis was laid on demonstration of the microvascularisation in the different hoof wall regions, aiming at assessment of specialised vascular structures, e.g. vascular sphincter mechanisms and arteriovenous anastomoses. Methods: The angioarchitecture of the adult pododerma in the equine hoof wall was examined by scanning electron microscopy of micro-corrosion casts assisted by exemplary histological and...
Vera L, De Clercq D, Paulussen E, Van Steenkiste G, Decloedt A, Chiers K, van Loon G.In human medicine, local and regional arterial wall stiffness (AWS) parameters are routinely used to assess the vascular health. In horses, information regarding reproducibility of ultrasonographically derived AWS parameters is lacking. Objective: To evaluate the inter-day and inter-observer and intra-observer measurement variability of both local and regional AWS parameters in horses. Methods: Experimental study. Methods: In 10 healthy, adult Warmblood horses, B-, M-mode and pulsed-wave Doppler ultrasound images were collected on two different days from aorta, cranial and caudal common caroti...
Vera L, Campos Arias D, Muylle S, Stergiopulos N, Segers P, van Loon G.Arterial rupture in horses has been observed during exercise, after phenylephrine administration or during parturition (uterine artery). In human pathophysiological research, the use of computer models for studying arterial hemodynamics and understanding normal and abnormal characteristics of arterial pressure and flow waveforms is very common. The objective of this research was to develop a computer model of the equine arterial circulation, in order to study local intra-arterial pressures and flow dynamics in horses. Morphologically, large differences exist between human and equine aortic arc...
Caivano D, Corda A, Rishniw M, Giorgi ME, Parpaglia MLP, Conti MB, Porciello F, Birettoni F.Equine cardiovascular structures and function are routinely assessed by transthoracic echocardiography. Recently, investigators have described the echocardiographic visualization of equine pulmonary vein ostia. In companion animals, the right pulmonary vein (RPV) to right pulmonary artery (RPA) ratio has been used as an index to estimate the severity of cardiac diseases resulting in left ventricular volume overload. We sought to assess the feasibility of measuring RPV and RPA dimensions, and sought to provide various previously examined RPV and RPA variables in clinically healthy horses that c...
Hughes J, Bardell D.To establish reference intervals for arterial blood-gas (ABG), acid-base and electrolyte values from a healthy equine population. Methods: Retrospective clinical study. Methods: A total of 139 client-owned, systemically healthy horses, 1 year of age and older, presented for elective surgical procedures. Methods: Blood samples were collected anaerobically from the transverse facial or common carotid artery of horses breathing room air, prior to administration of preanaesthetic medication. Samples were analysed immediately, without correction for body temperature, using an automated bench-top an...
Siwinska N, Michalek M, Zak A, Slowikowska M, Noszczyk-Nowak A, Niedzwiedz A, Paslawska U.Precise understanding of the dimensions of the vascular lumina is essential for accurate interpretation of cardiac vessels imaging. To the authors' best knowledge, this is the first study focusing on the ultrasound measurement of the right coronary artery (RCA) in the horse. The aim of this study was to determine both the ultrasonographic range of the normal diameter and lumen area of the RCA in horses and the influence of gender, age and level of training on the RCA dimensions. An additional aim of the study was to assess intra- and inter-observer repeatability of the collected measurements. ...
Davis JG, Ragle CA, Hanna A, DeNome AT.To determine the location of the deep and superficial caudal epigastric arteries in relation to 3 midline positions and the relationship between the location of these arteries, body circumference, and body condition score. Methods: Descriptive anatomical study. Methods: Nine horses, aged 1-28 years (mean 10.61 ± 8.89 SD). Methods: Body condition score and body circumference were measured prior to euthanasia. Angiographic studies of the deep and superficial caudal epigastric arteries were performed on resected abdominal walls. The distances between the deep and the superficial caudal epiga...
Rieger J, Hopperdietzel C, Kaessmeyer S, Slosarek I, Diecke S, Richardson K, Plendl J.Human and equine patients are known to frequently develop vascular complications, particularly thrombosis both in veins and arteries as well as in the microvasculature. Objective: The aim of the present study was to investigate and compare the angiogenic response of human and equine endothelial cells to lesions in an in vitro scratch assay. Methods: Endothelial cells from human umbilical vein (HUVEC), abdominal aorta (HAAEC) and dermal microvasculature (HDMEC) as well as equine carotid artery (EACEC) and jugular vein (EVJEC) were cultured and an elongated defect was created (scratch or "wound"...
Gonzalez-Cantero JL, Del Valle Diéguez M, Monteserín Matesanz C, Saura Lorente J, Villoria Medina F, Fortea Gil F, Castro Reyes E.We report a case of traumatic intracranial carotid artery pseudoaneurysm treated with an equine pericardium-covered stent. The patient was admitted to the Emergency Department after sustaining severe polytrauma in a motor vehicle accident. A cavernous carotid pseudoaneurysm was detected after an episode of massive epistaxis that required emergent nasal packing. Treatment with parent vessel sacrifice was ruled out after an unfavourable balloon test occlusion. We opted for an equine pericardium-covered stent as a means to immediately seal the wall defect in the setting of massive bleeding second...
Wilson KA, Raisis AL, Drynan EA, Mosing M, Lester GD, Hayman J, Hosgood GL.To determine the agreement of invasive blood pressure measured in the facial, metatarsal and carotid arteries, and evaluate the effects of two haemodynamic conditions on agreement. Methods: Prospective randomized study. Methods: A group of eight horses aged 7 (4-23) years with a body weight of 493 ± 33 kg. Methods: Horses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid arteries. Cardiovascular function and agreement between arteries was assessed before and during administr...
Wilson KAT, Raisis AL, Drynan EA, Lester GD, Hosgood GL.To determine agreement between invasive blood pressures measured in three peripheral arteries in anaesthetized horses undergoing elective surgery. Methods: Prospective balanced incomplete block design. Methods: A total of 18 client-owned horses. Methods: Invasive blood pressure (IBP) was measured simultaneously in one of the following three combinations: 1) transverse facial and facial artery; 2) transverse facial and metatarsal artery; and 3) facial and metatarsal artery. The agreement in blood pressure measured for each combination was performed in six horses. At each sample time, systolic (...
Kowalczyk K, Frąckowiak H.Considerable consistency in the arterial pattern of the head has been observed in species of Artiodactyla, but few studies have examined the order Perissodactyla. Here, we describe arteries supplying the intermandibular, mental, masseteric, buccal, labial, and nasal regions in eight perissodactylans, including representing of all families comprising this order. Observations were made on a total of 45 preparations of head arteries, obtained by injection of arteries with acetone-dissolved stained vinyl superchloride or stained latex LBS3060. In the Equidae species alone it was found that the fac...
Zizzadoro C, Caruso M, Punzi S, Crescenzo G, Zongoli F, Belloli C.Hemodynamic perturbations, partly resulting from abnormal vasoconstriction of digital vessels, have been implicated in the pathogenesis of bovine and equine laminitis. This study compared the responsiveness of isolated bovine (BDA) and equine (EDA) digital arteries to pharmacological agents that stimulate receptor systems involved in the regulation of normal vessel tone. The role of the endothelium and the short- and longer-term effects of an experimentally induced endothelial damage were also evaluated. Species-related differences were found in the vessel reactivity to all of the receptor ago...
Akbari G, Asadiahranjani B, Goodarzi N, Shokrollahi S.Donkeys are a member of the horse family (Equidae) and share a common ancestor. However, in morphological terms, donkeys and horses are regarded as two separate subgenus. Given variations in the branching pattern of the brachiocephalic trunk (BCT) in different species of animals and the use of donkeys in anatomy courses at colleges of veterinary medicine, we conducted this study in order to investigate the branching patterns of BCT and to describe detailed morphological information regarding donkeys. Seventeen mature donkeys were examined following euthanasia by exsanguination from the common ...
Khairuddin NH, Sullivan M, Pollock PJ.In horses, the extracranial and intracranial pathway of the internal carotid artery has been described. The extracranial pathway of the internal carotid artery begins at the carotid termination and runs on the dorsal surface of the medial compartment of the guttural pouch. Thereafter the internal carotid artery passes through the foramen lacerum to continue intracranially, forming part of the rostrolateral quadrants of the cerebral arterial circle (Circle of Willis). The objectives of this study were to define and record the anatomy of the carotid arterial tree and the internal carotid artery ...
Esteller-Vico A, Ball BA, Troedsson MHT, Squires EL.Equine pregnancy is characterized by very high circulating concentrations of estrogens. The physiological roles of estrogens during equine gestation are largely unknown, although some studies suggest a role in the regulation of uterine artery hemodynamics and a relationship between low circulating estrogen concentrations and late pregnancy loss. The objectives of this experiment were to evaluate the effects of estrogen suppression on uterine artery hemodynamics and on pregnancy outcome. Estrogen synthesis was suppressed using letrozole, a potent aromatase inhibitor. Twelve pregnant mares were ...
Silva GTA, Guest BB, Gomez DE, McGregor M, Viel L, O'Sullivan ML, Runciman J, Arroyo LG.Calcification of the tunica media of the axial pulmonary arteries (PA) has been reported in a large proportion of racehorses. In humans, medial calcification is a significant cause of arterial stiffening and is implicated in the pathogenesis of cardiac, cerebral, and renal microvascular diseases. Pulse wave velocity (PWV) provides a measure of arterial stiffness. This study aimed to develop a technique to determine PA-PWV in horses and, secondarily, to investigate a potential association between PA-PWV and arterial fibro-calcification. A dual-pressure sensor catheter (PSC) was placed in the ma...
Tapio H, Argüelles D, Gracia-Calvo LA, Raekallio M.To describe a modified technique for permanent translocation of the common carotid artery (CCA) to a subcutaneous position in standing horses. Methods: Experimental study. Methods: Healthy adult Standardbred and Warmblood horses (n = 8). Methods: Surgery was performed with the horses standing under sedation and with local anesthesia. A combination of previously described techniques was used modifying the approach and closure of the incision. The right CCA was approached through a linear skin incision dorsal and parallel to the jugular vein and through the brachiocephalicus and omohyoideus ...
Wilson DV, Rondenay Y, Shance PU.To characterize the acute cardiopulmonary effects of severe hemorrhage in anesthetized horses. Methods: Prospective experimental study. Methods: Three geldings and six mares, aged 14.4 ± 2.7 years, weighing 486 ± 41 kg (range: 425-550 kg). Methods: Horses were anesthetized using xylazine, guaifenesin, ketamine and halothane or isoflurane. Cardiovascular variables, hematocrit, total solids, capillary refill time (CRT) and color of mucous membranes were measured as blood was collected from the carotid artery into sterile plastic bags. Arterial blood gas analysis was also performed. Results: Th...
Saey V, Ploeg M, Delesalle C, van Loon G, Gröne A, Ducatelle R, Duchateau L, Chiers K.Rupture of the aorta is much more common in Friesians compared with other breeds of horse. Rupture always occurs adjacent to the scar of the ligamentum arteriosum. Previous histological examination of ruptured aortic walls suggested the presence of an underlying connective tissue disorder. Therefore, the aim of the present study was to compare the structural characteristics of the tunica media of the mid-thoracic aorta, distant to the lesion, in warmblood and Friesian horses with and without thoracic aortic rupture. In unaffected Friesian horses, the thickness of the tunica media, as well as t...
Stack A, Derksen FJ, Williams KJ, Robinson NE, Jackson WF.Regional differences in large equine pulmonary artery reactivity exist. It is not known if this heterogeneity extends into small vessels. The hypothesis that there is regional heterogeneity in small pulmonary artery and vein reactivity to sympathomimetics (phenylephrine and isoproterenol) and a parasympathomimetic (methacholine) was tested using wire myography on small vessels from caudodorsal (CD) and cranioventral (CV) lung of 12 horses [9 mares, 3 geldings, 8.67 ± 0.81 (age ± SE) yr, of various breeds that had never raced]. To study relaxation, vessels were precontracted with U46619 (10(-...
van Oostrom H, Schaap MW, van Loon JP.Hypoventilation or apnoea, caused by the induction of general anaesthesia, may cause hypoxaemia. Preoxygenation may lengthen the period before this happens. No scientific studies are published on preoxygenation in equine anaesthesia. Objective: To determine whether supplementation of oxygen at a flow rate of 15 l/min for 3 min via a nasal cannula before induction of general anaesthesia is effective in elevating the arterial partial pressure of oxygen (PaO ) directly after induction. Methods: Randomised, prospective clinical trial. Methods: A total of 18 American Society of Anesthesiologists ph...
Cousty M, Tricaud C, De Beauregard T, Picandet V, Bizon-Mercier C, Tessier C.The objective of the study was to evaluate the effect of ligation of the ipsilateral common carotid artery (CCA) combined with various antimycotic treatments for the prevention of epistaxis in horses with guttural pouch mycosis. For each case, ipsilateral ligation of the CCA was performed, followed by application of various topical medications under endoscopic guidance. Frequency and number of treatments, outcome and recurrence of haemorrhage were retrospectively recorded. Twenty-four horses were included. Topical medication was administered by detachment of the diphtheric membrane and sprayin...
Bonilla AG, Scansen BA, Hurcombe SD, Mudge MC.2 horses were examined for chronic nasal discharge secondary to unilateral guttural pouch mycosis. Results: Initial endoscopic examination of both horses confirmed the presence of a fungal plaque on the dorsomedial aspect of the medial compartment of the guttural pouch (auditory tube diverticulum) involving the internal carotid artery (ICA). No signs of hemorrhage or neurologic deficits were present at admission. Results: Transarterial stainless steel coil embolization of the affected ICA was performed under general anesthesia, with fluoroscopic guidance. During treatment, an aberrant branch o...
Saey V, Famaey N, Smoljkic M, Claeys E, van Loon G, Ducatelle R, Ploeg M, Delesalle C, Gröne A, Duchateau L, Chiers K.Thoracic aortic rupture and aortopulmonary fistulation are rare conditions in horses. It mainly affects Friesian horses. Intrinsic differences in biomechanical properties of the aortic wall might predispose this breed. The biomechanical and biochemical properties of the thoracic aorta were characterized in warmblood horses, unaffected Friesian horses and Friesians with aortic rupture in an attempt to unravel the underlying pathogenesis of aortic rupture in Friesian horses. Samples of the thoracic aorta at the ligamentum arteriosum (LA), mid thoracic aorta (T1) and distal thoracic aorta (T2) we...
Khairuddin NH, Sullivan M, Pollock PJ.To record the angiographic anatomy of the equine internal carotid artery (ICA) using angiography techniques. Methods: In vitro descriptive study. Methods: Equine cadaver specimens (n = 50). Methods: Head and neck specimens from horses of mixed breed, age, sex, and use without a history of guttural pouch disease had carotid and cerebral angiography using conventional (n = 7) and rotational angiography (43). Angiographic findings were verified by arterial latex casts. Results: Variation in ICA anatomy was categorized into 4 groups: (1) the internal carotid and occipital arteries arising ...
Steffey EP, Howland D.Cardiovascular effects of venous alveolar concentrations of halothane in oxygen were studied in 8 young, healthy horses under conditions of constant arterial carbon dioxide tension. The alveolar concentration of halothane was expressed as a multiple of the minimal alveolar concentration (MAC) which was known for each animal. Increasing alveolar halothane concentrations to MAC 2.0 resulted in a progressive and significant (P less than 0.05) decline in systemic arterial pressure and left ventricular work. Cardiac output decreased between MAC 1.0 and MAC 2.0 as a result of a significant (P less t...
Simonsen U, Prieto D, Hernández M, Sáenz de Tejada I, García-Sacristán A.To study the influence of alpha-adrenergic stimuli on non-adrenergic non-cholinergic (NANC) neurogenic relaxation in isolated horse penile resistance arteries. Methods: Deep intracavernous penile arteries with an internal lumen diameter of 200-500 microns., isolated from the corpus cavernosum of young horses, were mounted in microvascular myographs for isometric tension recording and electrical field stimulation (EFS) of autonomic nerve terminals. Results: In the presence of guanethidine (10(-5) M) and atropine (10(-7) M) tone of the arteries was raised by the thromboxane analogue, U46619. EFS...
Slocombe JO, McCraw BM, Pennock PW, Vasey J.Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. Approximately 8 weeks after they were inoculated, 6 foals were given ivermectin IM at a dosage rate of 200 micrograms/kg of body weight and 6 were given a placebo. All foals were necropsied 35 days after treatment. Ivermectin was 98.9% effective in eliminating later 4th-stage S vulgaris larvae located near the origin of major intestinal arteries and in reducing clinical signs and permitting resolution of lesions associated with verminous arteritis. One pony foal reared on pasture and with evidence of arteritis of ...
Larenza MP, Knobloch M, Landoni MF, Levionnois OL, Kronen PW, Theurillat R, Schatzmann U, Thormann W.The pharmacokinetics of ketamine and norketamine enantiomers after administration of intravenous (IV) racemic ketamine (R-/S-ketamine; 2.2 mg/kg) or S-ketamine (1.1 mg/kg) to five ponies sedated with IV xylazine (1.1mg/kg) were compared. The time intervals to assume sternal and standing positions were recorded. Arterial blood samples were collected before and 1, 2, 4, 6, 8 and 13 min after ketamine administration. Arterial blood gases were evaluated 5 min after ketamine injection. Plasma concentrations of ketamine and norketamine enantiomers were determined by capillary electrophoresis and wer...
Esteller-Vico A, Ball BA, Troedsson MHT, Squires EL.Equine pregnancy is characterized by very high circulating concentrations of estrogens. The physiological roles of estrogens during equine gestation are largely unknown, although some studies suggest a role in the regulation of uterine artery hemodynamics and a relationship between low circulating estrogen concentrations and late pregnancy loss. The objectives of this experiment were to evaluate the effects of estrogen suppression on uterine artery hemodynamics and on pregnancy outcome. Estrogen synthesis was suppressed using letrozole, a potent aromatase inhibitor. Twelve pregnant mares were ...
Colles CM, Hickman J.Macroscopic, microscopic and radiological examinations of the navicular bones of 83 horses and ponies showed that the navicular bone in the adult horse has 2 principal routes of blood supply. One supply is present at birth, the other develops within the first 2 to 3 years of life, in response to increasing activity. The size of the nutrient foramina, as seen on radiographs, is related to the type, frequency and regularity of work done by the horse. These foramina are normally conical in shape, alteration to a circular, or mushroom-shape being evidence of occlusive vascular disease in the navic...
Rumbaugh ML, Burba DJ, Natalini C, Hosgood G, Moore RM.To compare arterial bursting pressure after vessel closure using a vessel-sealing device (LigaSure Atlas Laparoscopic Sealer/Divider Instrument; Valleylab, Boulder, CO), a ligate-and-divide stapling device (LDS), and 2-0 polydioxanone suture. To evaluate the LigaSure Atlas as a method for ligation of the mesenteric vasculature during small intestinal resection in normal horses. Methods: Experimental study. Methods: Part A: jejunal segments from 19 horses. Part B: 6 horses, aged 1 to 18 years, weighing 330 to 509 kg. Methods: Part A: Jejunal segments with mesenteric vessels were collected from ...
Freeman DE, Donawick WJ.An intravascular procedure was used to occlude the internal carotid artery of two horses with epistaxis caused by guttural pouch mycosis. In each horse, the affected internal carotid artery was ligated close to its origin. A balloon-tipped catheter was introduced into the artery distal to the ligature, and its tip was advanced beyond the site of infection. The balloon was then inflated so that the infected segment of artery was isolated from the cerebral vascular system. The catheters were removed at 14 and 51 days, and both horses were returned to training and racing. Neither horse had furthe...
Flores J, Corvera Poiré E, del Rio JA, López de Haro M.We consider a simple model to give a plausible mechanical explanation of what are the actual resting heart rates of mammals optimized for. We study what is the optimal frequency for a viscoelastic fluid circulating in a pulsatile way through a network of tubes and conclude that the heart rate is not optimized to transport blood through the whole net. Rather, actual resting heart rates of mammals happen at frequencies that optimize flow in vessels of radii that correspond to large arteries, which bring oxygenated blood rapidly far away from the heart, towards head and limbs. Our results for the...
Prieto D, Hernández M, Rivera L, García-Sacristán A, Simonsen U.The distribution of neuropeptide Y (NPY)-immunoreactive (IR) nerves, as well as the functional effects of NPY and the Y1- and Y2-receptor agonists, [Leu31,Pro34]NPY and NPY(13-36), respectively, have been investigated in vitro in both visceral and arterial smooth muscle of the horse intravesical ureter. NPY-IR nerve fibres were widely distributed along the entire length of the ureter, although the intravesical part was the most richly innervated region, and the only one where NPY-IR ganglion cells were found. NPY (10(-7) M) did not affect either basal tone or spontaneous rhythmic contractions ...
Manohar M, Gustafson R, Goetz TE, Nganwa D.Effects of 1.1, 1.5, and 1.8 minimal alveolar concentration (MAC) isoflurane-O2 (1.45%, 1.96%, and 2.39% end-tidal isoflurane, respectively) anesthesia on cardiac output, blood pressure, and blood flow to the brain, thyroid glands, adrenal glands, kidneys, and splanchnic organs were examined in 9 healthy isocapnic adult ponies. Tissue blood flows were studied using 15-micron diameter radionuclide-labeled microspheres that were injected into the left ventricle, and comparisons were made with data obtained from ponies in the conscious state. Isoflurane anesthesia caused dose-related reduction in...
Baxter GM, Laskey RE, Tackett RL, Moore JN, Allen D.The in vitro reactivity of vasoconstrictive mediators that are implicated in acute laminitis was determined in palmar and plantar digital arteries and veins obtained from healthy horses and in palmar digital vessels of horses with early laminitis (Obel grade I). To obtain baseline reactivity data, 3 experiments were conducted, using healthy horses: (1) the reactivity of palmar and plantar digital arteries and veins to angiotensin II, norepinephrine, and 5-hydroxytryptamine (serotonin) were compared; (2) the direct effects of bacterial endotoxin on vascular reactivity were assessed; and (3) the...
Saey V, Ploeg M, Delesalle C, van Loon G, Gröne A, Ducatelle R, Duchateau L, Chiers K.Rupture of the aorta is much more common in Friesians compared with other breeds of horse. Rupture always occurs adjacent to the scar of the ligamentum arteriosum. Previous histological examination of ruptured aortic walls suggested the presence of an underlying connective tissue disorder. Therefore, the aim of the present study was to compare the structural characteristics of the tunica media of the mid-thoracic aorta, distant to the lesion, in warmblood and Friesian horses with and without thoracic aortic rupture. In unaffected Friesian horses, the thickness of the tunica media, as well as t...
Lévéille R, Hardy J, Robertson JT, Willis AM, Beard WL, Weisbrode SE, Lepage OM.To develop a transarterial coil embolization technique for occlusion of the internal carotid artery (ICA), external carotid artery (ECA), and maxillary arteries (MA) in normal horses and to evaluate this technique for prevention of hemorrhage in horses affected with guttural pouch mycosis. Methods: Ten adult, normal horses and 4 horses with guttural pouch mycosis. Methods: All horses had transarterial coil embolization of the rostral and caudal ICA, caudal MA, and rostral ECA. In 1 affected horse, an aberrant actively bleeding branch of the ECA was also occluded. Normal horses had a premortem ...
Ueno T, Nambo Y, Tajima Y, Umemura T.Broad ligament haemorrhage in peripartum mares is a life-threatening disease and there are few reports on the aetiology and pathogenesis of broad ligament haematoma. Objective: To obtain information regarding the sites for the early diagnosis and pathogenesis of broad ligament haematoma of mares. Methods: Thirty-one mares that died of broad ligament haematoma peripartum were examined pathologically for bleeding sites. The arterial distribution of 5 young mares with several parities served as negative controls. Results: Age and/or multiparity were the predisposing factors for the disease. Arter...
Sleutjens J, Smiet E, van Weeren R, van der Kolk J, Back W, Wijnberg ID.To evaluate the effect of various head and neck positions on intrathoracic pressure and arterial oxygenation during exercise in horses. Methods: 7 healthy Dutch Warmblood riding horses. Methods: The horses were evaluated with the head and neck in the following predefined positions: position 1, free and unrestrained; position 2, neck raised with the bridge of the nose aligned vertically; position 4, neck lowered and extremely flexed with the nose pointing toward the pectoral muscles; position 5, neck raised and extended with the bridge of the nose in front of a vertical line perpendicular to th...
Gasthuys F, de Moor A, Parmentier D.The effects of change in position and respiration modes were studied in 5 experimental ponies during a standard halothane anaesthesia. A marked cardiovascular depression (decrease in mean arterial blood pressure, cardiac output, stroke volume and left ventricle work) occurred in recumbent, spontaneously breathing ponies. No significant differences were found between right and left lateral recumbency. The most pronounced cardiovascular depression was observed in the dorsal position. Sternal recumbency appeared to be slightly beneficial (higher systemic blood pressure and arterial oxygenation). ...
Matsuda Y, Nakanishi Y, Mizuno Y.Occlusion of the internal carotid artery by insertion of intravascular platinum microcoils for guttural pouch mycosis was experimentally evaluated in 9 healthy adult Thoroughbred horses. The internal carotid artery was ligated to its origin, and an arteriotomy was made distal to the ligature, which was then occluded by insertion of the microcoil approximately 13 cm distal to its origin. Cessation of blood flow was determined visually and by angiography at the arteriotomy site. Six horses were evaluated for complication clinically and by endoscopy after surgery. One horse was necropsied after 3...
Malan FS, Reinecke RK, Scialdo RC.The entire gastro-intestinal tract and viscera of the abdomen and thorax, including the heart, aorta and its branches to the viscera, are removed from the carcass. All the branches of the aorta, with the exception of the A. gastrica sinistra, are dissected from the intestinal tract, and subsequently each branch is isolated from the mesentery, fat, pancreas, kidneys, etc. Usually, the A. ileocolica is grossly enlarged due to chronic arteritis with thrombus formation caused by 4th stage larvae, 4th moult and 5th stage Strongylus vulgaris. Descriptions of methods to examine the subperitoneal tiss...
Molyneux GS, Haller CJ, Mogg K, Pollitt CC.In the foot of the horse, arteriovenous anastomoses (AVAs) of epithelioid type occurred in the dermis of the coronary band, in the coronary and terminal papillae, in neurovascular bundles and at the entrance to and along the length of the dermal laminae. A particular feature of the epithelioid segment of AVAs in the horse, compared with that of other species, was the height and surface complexity of many of the endothelial cells. They extended into the lumen, forming undercut and tunnel-like areas which correlated with the characteristic surface marking of AVAs observed in vascular casts. The ...
Durando MM, Martin BB, Hammer EJ, Langsam SP, Birks EK.The primary goal was to investigate the relationship between dynamic upper airway abnormalities and arterial blood gas tensions during exercise. Horses that completed a high-speed treadmill examination consisting of upper-airway videoendoscopy, blood gas evaluation and electrocardiogams and, postexercise, echocardiograms and tracheal washes, were included. An age-matched group of fit, healthy Thoroughbreds, trained to run on a high-speed treadmill, served as controls for blood gas values at specific exercise speeds. One hundred and nineteen horses completed the treadmill examination. Sixty (50...
Venugopal C, Mariappan N, Holmes E, Kearney M, Beadle R.To determine and compare the reactive oxygen and nitrogen species (ROS and RNS) in pulmonary tissues of horses affected with recurrent airway obstruction (RAO) and clinically healthy horses, and to evaluate the effectiveness of potential therapeutic agents in reducing ROS and RNS in the tissues of these horses. Objective: We hypothesised that RAO-affected horses would have high levels of reactive species and that the test agents would reduce them. The objectives were as follows: 1) to determine the level of ROS and RNS in pulmonary tissues (bronchial and arterial rings) of RAO-affected and cli...
Morgan SJ, Stromberg PC, Storts RW, Sowa BA, Lay JC.Histological and morphometric evaluation of equine cranial mesenteric arteries was performed on 239 and 89 arteries, respectively. Histological examination revealed that thrombosis and the severity of inflammation varied on a seasonal basis and were directly associated with larval presence. Intimal and adventitial fibrosis were generally of greater severity than medial fibrosis. Fibrosis of the vasa vasorum was less frequent than fibrosis of the artery itself. Morphometry revealed a significant increase in intimal, adventitial and, to a lesser extent, medial area in affected as compared with n...
MacEachern KE, Smith GL, Nolan AM.Equine endothelial cells were isolated from the pulmonary artery by enzymatic digestion and grown to confluency. The cells were characterised by positive immunofluorescent staining for von Willebrand factor and NADPH-diaphorase staining for nitric oxide synthase. Measurements of endothelins indicated that there were significant release rates from the cells for up to six hours. Measurements of intracellular calcium concentration showed that the application of bradykinin caused a transient increase in calcium concentration with similar characteristics to those observed in other endothelial cell ...
Manohar M, Goetz TE.The present study examined whether Thoroughbred horses performing strenuous exercise exhibit intrapulmonary arteriovenous shunting that may contribute to the observed arterial hypoxemia. Experiments were carried out on seven healthy, exercise-trained Thoroughbreds at rest, maximal exercise (galloping at 14 m/s on a 3.5% uphill grade for 120 s), and submaximal exertion (8 m/s on a 3.5% uphill grade for 150 s). Along with blood gas/hemodynamic parameters, intrapulmonary arteriovenous shunting was studied by injecting 15-microm-diameter microspheres, labeled with different stable isotopes, into t...
Chaffin MK, Matthews NS, Cohen ND, Carter GK.A commercially available pulse oximeter was evaluated in anaesthetised foals to determine its accuracy for estimating arterial haemoglobin saturation (SaO2). Five different transducer/transducer attachment site (TTAS) combinations were evaluated; 1-3) a fingertip transmission transducer attached to the foal's ear, lip and tongue, 4) an adhesive transmission transducer positioned on the foal's ear and 5) a forehead reflectance transducer placed on the ventral aspect of the foal's tail-base. Eight normal, Quarter Horse foals (age 5-10 days) were studied while under general anaesthesia. Alteratio...
Gleed RD, Dobson A.Observations were made on horses spontaneously breathing oxygen, with halothane at a constant end tidal concentration. The horses were positioned in dorsal recumbency for the first 45 minutes of each anaesthetic episode during which the arterial oxygen tension (PaO2) was found to peak and then decline. The remaining 60 minutes of each anaesthesia was used to test the effect of various manoeuvres on PaO2. The PaO2 of horses decreased further both when remaining in dorsal recumbency and when repositioned in right or left recumbency. In contrast, placing the horses in sternal recumbency for these...
Saey V, Famaey N, Smoljkic M, Claeys E, van Loon G, Ducatelle R, Ploeg M, Delesalle C, Gröne A, Duchateau L, Chiers K.Thoracic aortic rupture and aortopulmonary fistulation are rare conditions in horses. It mainly affects Friesian horses. Intrinsic differences in biomechanical properties of the aortic wall might predispose this breed. The biomechanical and biochemical properties of the thoracic aorta were characterized in warmblood horses, unaffected Friesian horses and Friesians with aortic rupture in an attempt to unravel the underlying pathogenesis of aortic rupture in Friesian horses. Samples of the thoracic aorta at the ligamentum arteriosum (LA), mid thoracic aorta (T1) and distal thoracic aorta (T2) we...
