Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Tschudi P.The technique of needle biopsy, the examination of aspirated bone marrow and the interpretation of bone marrow smears are described. The indications for a bone marrow biopsy are listed and the literature is reviewed. The significance of this examination is illustrated with some clinical cases.
Daunt DA.In conclusion, vigilant supportive care is necessary to prevent morbidity and death in the anesthetized horse. Because some of the equipment and drugs are specialized and the consequences of some postanesthetic complications are severe, availability of those items must be confirmed prior to anesthesia. Proper positioning and padding will help to reduce the incidence of postanesthetic myopathy-neuropathy syndrome in these large patients. Adequate tissue perfusion is important and can be achieved by controlling anesthetic depth, increasing intravascular volume with fluid administration, and by a...
Payne RC, Sukanto IP, Graydon R, Saroso H, Jusuf SH.During an outbreak of trypanosomiasis in cattle, buffalo and horses on the island of Madura, a survey was conducted to determine the prevalence of Trypanosoma evansi in the region. Blood samples were collected from 130 cattle and 147 buffalo in 5 villages, whole blood was examined for trypanosomes by the microhaematocrit (MHCT) method and serum samples were subjected to an enzyme linked immuno absorbent assay to detect T. evansi antibodies. T. evansi was detected by MHCT in 50% of the buffalo examined and 13% of the cattle, while antibodies were detected in 47% of the buffalo and 30% of the ca...
Riebold TW.In conclusion, monitoring the depth of anesthesia plays an integral role in the anesthetic regimen. Although the use of sophisticated monitoring equipment has replaced some of the art of anesthesia and made assessment of depth of anesthesia more precise, a vigilant clinician still needs to serve as the animal's advocate. He or she must gather the data that are generated by machines, acquire data that monitoring equipment cannot obtain, assimilate all the facts, and make appropriate changes in anesthetic management.
Hunt RJ, Hay W, Collatos C, Welles E.Two adult horses had colic attributable to spermatic cord torsion and strangulation of abdominally retained neoplastic testes. Both horses had caudal abdominal soft tissue masses palpable per rectum. One horse was treated successfully by surgical removal of the testis, and the other was euthanatized without treatment. Histopathologic diagnosis of the involved testes was testicular seminoma. Spermatic cord torsion of an abdominally retained testis should be considered in the differential diagnosis of signs of abdominal pain in cryptorchid stallions, especially those with a palpable caudal abdom...
Friedhoff KT, Tenter AM, Müller I.The geographical distribution of Babesia equi and Babesia caballi and their tick vectors is discussed. Control of infections with these protozoa is hampered by the lack of a suitable antiprotozoal drug and a reliable serological test. No vaccine is available. Ehrlichia risticii (the causal agent of Potomac horse fever) and E. equi are rickettsial parasites which are difficult to control. Little is known of their geographical distribution and vectors. Early diagnosis is required for tetracycline therapy to be effective and there is a need for a rapid test to provide an early diagnosis.
Kempson SA.Farrier's Formula feed supplement was added to the diet of 18 horses with two types of hoof horn defects. The first group of horses showed sand cracks and crumbling horn around the nail holes; the second group suffered frequent bruising and had flat feet with collapsed heels. Hoof clippings from both groups were studied in the transmission and scanning electron microscopes. All the horses showed a progressive improvement in the gross and microscopic structure of the hoof horn, starting six weeks after the supplementation began. Once good quality hoof horn had grown there was no relapse during ...
Abrahamsen EJ, Bohanon TC, Bednarski RM, Hubbell JA, Muir WW.An 8-year-old Quarter Horse gelding was anesthetized for surgical exploration and debridement of a chronic draining wound in the intermandibular space. Anesthesia was without complication other than persistently low PaO2. Severe airway obstruction was evident immediately after extubation, requiring tracheostomy. Endoscopic diagnosis was bilateral arytenoid paralysis, which gradually resolved over the next 7 days. Compression, trauma, or tension of the recurrent laryngeal nerves are the postulated causes of idiopathic laryngeal hemiplegia in horses. The extremely extended position of the head a...
Rikihisa Y, Reed SM, Sams RA, Gordon JC, Pretzman CI.In August 1986, an extensive serosurvey for prevalence of IgG and IgM antibodies against Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME), was performed at 2 Ohio racetracks, River Downs (RD) and Beulah Park (BP). Of 840 horses at RD and 574 at BP, 13 and 20%, respectively, were IgG antibody-positive (by indirect fluorescent antibody test results), with antibody titer ranging from 1:20 to 1:10,240. The titer observed at highest frequency at both racetracks was 1:80. A higher proportion of horses was ill at RD (operating during the summer months) than at BP (winter...
Gaughan EM, Hackett RP.Over a 10-year period, cecocolic intussusception was diagnosed in 11 of 842 horses undergoing surgical treatment for colic at the New York State College of Veterinary Medicine. Eight horses died or were euthanatized because of poor prognosis determined at surgery or because of postoperative complications. Three horses recovered without complication after manual reduction of the intussusception and partial typhlectomy, using an intestinal stapling device.
Harris PA.An outbreak of muscle stiffness and poor performance among 59 thoroughbreds at a Newmarket flat racing yard was investigated between the beginning of May and the end of June 1986. Over a third of the horses showed signs of muscular stiffness, and 38 had, at one or more of the sampling times, creatine kinase (CK) activities above 200 iu/litre and, or, aspartate aminotransferase (AST) activities above 300 iu/litre when they were sampled six to eight hours after exercise. The following season, at a similar time and stage of training, only four of 39 horses sampled had CK activities between 200 an...
Steffey EP, Woliner MJ, Dunlop C.Circulatory and respiratory effects of five h of constant 1.06 per cent alveolar halothane in oxygen were identified in eight healthy horses, which breathed spontaneously, were otherwise unmedicated and positioned in sternal recumbency. Only a few important significant (P less than 0.05) changes occurred with time. Total peripheral resistance was about 15 per cent lower after two hours of constant dose halothane than after 30 mins of constant dose (P less than 0.05) and accounted for the significant 10 per cent reduction in mean carotid arterial blood pressure. By 5 h, the reduction in resista...
Doreau M, Boulot S, Barlet JP, Patureau-Mirand P.The yields and composition of milk from nursing mares were studied during the first two months of lactation in 11 mares of heavy breeds (784 kg). Daily yield increased from 21.7 to 24.6 kg between weeks 1 and 8 of lactation. Fat, protein, gross energy and Ca concentrations significantly decreased when lactose content increased during this period. Individual variations were higher for yield than for composition. Casein, whey protein and non-protein N (56, 34 and 10% of crude protein, respectively) and amino acid composition did not vary between weeks 1 and 8 of lactation.
Pemberton AD, Hodgson JC, Gilmour JS, Doxey DL.Isolates were prepared from the sera of 12 horses with acute grass sickness, using methods reported to yield serum fractions associated with neurotoxicity, and their components identified by liquid chromatography and spectroscopy. All isolates were found to contain cortisol and six isolates also contained a degradation product of an analgesic drug, dipyrone. However, no recognised neurotoxin was detected.
Pycock JF, Allen WE.Exudate and uterine flushings were collected at either 30, 60, 120 or 240 mins after intrauterine infusions of Streptococcus zooepidemicus in genitally normal mares during oestrus. Uteri were also flushed without prior induction of endometritis. Protein concentrations in exudate and flushings increased with time and exudate pH decreased with time; the pH of flushings did not alter. Lysozyme and lactate dehydrogenase were present in flushings from non-infected uteri, but concentrations increased with time after infection. Immunoreactive prostaglandin E2 was undetectable before infection, but co...
Snyder JR, Pascoe JR, Olander HJ, Hinds DM, Young R, Tyler WS.Ten horses were euthanatized before, during, or after surgery to correct severe volvulus of the large colon. At surgery, the colonic serosa changed from blue-gray, blue or purple toward a more normal pink in seven horses after the volvulus was corrected. The mucosa consistently remained black or dark red. Results of postmortem colonic microangiography revealed perfusion of the serosa and the circular and longitudinal muscle layers, but mucosal perfusion was limited by thrombosis in the muscularis mucosae and submucosa. There was evidence of thrombosis of the mesenteric colic vessels in six hor...
Orsini JA, Buonanno AM, Richardson DW, Nunamaker DN.A Salter-Harris type-II fracture of the distal portion of the femur in a 1-year-old Pony of America was repaired by use of lateral plating combined with interfragmentary compression. The configuration of the fracture and the method of internal fixation with a condylar buttress plate were unique and resulted in primary bone healing, seen at the 5-month follow-up examination.
Racklyeft DJ.Transtracheal aspirate (TTA) aerobic microbiology culture results from 30 ponies were compared to protected catheter brush (PCB) culture results obtained from the same ponies. The PCB procedure resulted in significantly fewer (13<0.05) isolates than those obtained by the TTA procedure and the PCB procedure resulted in significantly more samples with no bacteria growth than the TTA procedure. To address the possibility that the volume of tracheobronchial secretion obtained by PCB was insufficient as a microbiological sample, a sterile, double-sheathed, protected aspiration catheter (PAC) was de...
Vörös K, Holmes JR, Gibbs C.This study was performed on 15 horses to validate the cardiac anatomy as imaged with two dimensional echocardiography (2DE) and to determine the accuracy of intracardiac measurements. 2DE images were recorded in five horses in life with a Diasonics DRF100 ultrasound system and a 3.5 MHz transducer in different tomographic planes. After slaughter, the hearts were fixed in 10 per cent formalin. To compare in vivo and in vitro results, the specimens were suspended in a water-filled tank and 2DE images were made using the same transducer positions as in life. In vitro 2DE and autopsy measurements ...
Cancedda M.In this paper some considerations on the environment of the 42 Kmq of the volcanic-basaltic Giara tableland are discussed. Conditioning by the environment and its effect on the distribution of a population of 712 horses is illustrated in view of their social and behavioural organization.
Heinrichs M, Baumgärtner W, Capen CC.Adenomas of the pars intermedia from 19 horses and normal pituitary glands from seven horses were evaluated histologically and immunocytochemically for adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin (beta-END), proopiomelanocortin (POMC), prolactin, neuron specific enolase, and glial fibrillary acidic protein (GFAP). The 26 horses ranged in age from 7 to 31 years. Histologically, all adenomas had a uniform pattern characterized by cords of large columnar cells forming palisades and pseudoacini separated by a delicate fibrovascular stroma. I...
Mayhew IG, Washbourne JR.Brainstem auditory evoked potential (BAEP) waveforms were recorded as a means of objectively evaluating auditory and brainstem function in horses. BAEP recordings were readily and repeatably recorded from horses, under minimal restraint, using signal averaging equipment. Clearly identified BAEP waveforms were obtained with compression clicks of 30-100 dB (HHL) at 10 Hz applied in the external auditory meatus of one ear and masking white noise (10 dB lower) in the other ear. Vertex positive (upwards) waveforms I through V were obtained with an active, subdermal electrode over the ipsilateral an...
Käsbohrer A, Schönberg A.The prevalence of B. burgdorferi, the causative agent of Lyme Borreliosis in humans, was determined in domestic animals living in Berlin. 189 dogs, 29 cats, 224 horses and 194 cows were investigated. Using the indirect immunofluorescence test (IFT) 5.8% of the dogs and 24.5% of the cows investigated showed a positive reaction at titres of 1:128 or higher. Horses and cats gave negative results. ELISA was more sensitive than IFT. 10.1% of the dogs, 16.1% of the horses and 66% of the local cows showed positive reaction. Domestic animals seem to be in contact with B. burgdorferi and can be a reser...
Sirois J, Kimmich TL, Fortune JE.Ovulation in mares is preceded by a long and variable estrous period. The differentiation of equine preovulatory follicles with respect to steroidogenic capacity and responsiveness to equine gonadotropins was studied by culturing pieces of follicle wall (FW = theca + attached granulosa cells) from preovulatory follicles isolated during late diestrus (day 14 of cycle, n = 5 mares), early estrus (1st-2nd day of estrus, n = 6) or late estrus (4th or 5th day of estrus, n = 6). FW was cultured with or without equine LH, FSH, LH + FSH, or CG (10 or 100 ng/ml) and medium was collected and replaced at...
Mogg TD, Pollitt CC, Willmore JP, Thompson H.Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less tha...
Woods J, Bergfelt DR, Ginther OJ.The effects of pre-ovulatory and post ovulatory insemination on pregnancy rate and embryonic-loss rate were studied in 268 mares in two experiments. Within each experiment mares were randomised within replicates as follows: to be inseminated on the day the pre-ovulatory follicle reached 35 mm (pre-ovulatory group), to be inseminated on the day of ovulation (Day 0 group), and to be inseminated on the day after ovulation (Day 1 group). Ultrasonic pregnancy diagnoses were performed on Days 11, 12, 13 and 14 (Experiment 1) and Days 11, 12, 13, 14, 15, 20 and 40 (Experiment 2). Combined for the two...
Arden WA, Slocombe RF, Stick JA, Parks AH.Morphologic changes in equine jejunal segments subjected to 1 hour of ischemia and 1 hour of reperfusion, and protective effects of systemic administration of dimethyl sulfoxide (DMSO; 1 g/kg of body weight) were investigated in 18 ponies, using light microscopy and scanning and transmission electron microscopy. Ponies were allotted to 4 groups: group 1--control (n = 3); group 2--DMSO (n = 3); group 3--ischemia (n = 6); and group 4--ischemia and DMSO (n = 6). In each pony, 2 jejunal sections were evaluated. The first section was obtained prior to induction of ischemia, and the second was obtai...
Carter SW, Robertson SA, Steel CJ, Jourdenais DA.Six healthy foals underwent instrumentation for measurement of the cardiopulmonary effects of sedation with 1.1 mg/kg bodyweight xylazine hydrochloride given intravenously. Responses to xylazine in foals at 10 and 28 days of age were not significantly different. Foals became sedate and markedly ataxic, and four of the six foals became recumbent. Heart rate decreased significantly but no arrhythmias were detected. Arterial blood pressure increased initially and then fell significantly below pre-injection values. Changes in respiratory airflow, upper airway obstruction and respiratory noise were...
Bohanon TC, Beard WL, Robertson JT.Case records of 27 draft horses with laryngeal hemiplegia were reviewed. Twenty-one horses were treated by ventriculectomy with or without prosthetic laryngoplasty, and 17 owners were contacted to determine the results. Fifteen horses improved after surgery and were able to perform to the owners' expectations. Performance improved significantly and hospitalization was shorter after ventriculectomy alone. Results of this study indicate that the clinical signs of exercise intolerance and excessive inspiratory noise associated with left laryngeal hemiplegia in draft horses can be treated successf...
Steel JD, Hall MC, Stewart GA.Changes that occur in the equine ECG during and after exercise have been described and compared with resting ECG's obtained from the same horses. When the speed of work equals or is greater than "three-quarter pace" (i.e. "even time" or 200 metres in 15 seconds) the high heart rates developed cause the loss of ECG waveforms that are readily discernible at rest. Although differences in the waveforms between horses with normal and abnormal resting ECG's have been observed, the more definitive useful information is the fact that abnormal horses showed significantly higher heart rates than normal ...
Carroll EJ, Lasmanis J, Schalm OW.A method is described for production of an equine anti-bovine leukocyte serum (EABLS). Leukocytes were harvested from the milk of cow's udders which had been irritated with endotoxin. The washed leukocytes as antigens were administered to 2 horses in a series of subcutaneous and intravenous injections. There was a variably progressive increase in total serum proteins and a decrease in albumin/blobulin ratios, but the most pronounced change was an increase in beta2-globulins. Accompanying these changes was an increase in the number of precipitin lines as shown by Ouchterlony analysis. Four old ...
Fontaine M, Aymard-Henry M.From the Revised Nomenclature of WHO, the fowl influenza virus A/Duck/Ukraine/63 (Hav7 Neq2) has the same neuraminidase as the equine virus A/equi 2/Miami/63 (Heq2 Neq2); the A/Chicken Germany "N"/49 virus has the same neuraminidase as the equine virus A/equi 1/Prague/56. A comparative study of the antigenic specificities confirms that the Neq2 neuraminidases are closely connected, whatever their animal origin, and that the fowl strain Hav7 Neq2 can be used for the titration of anti Neq2 antibodies in the serums of animals immunized with the equine virus Heq2 Neq2. The Neqi neuraminidases of v...
Saiatov MKh, Beĭsembaeva RU.Profiles of distribution of non-specific gamma-inhibitors of influenza A2/Victoria/35/72 in donkey and horse sera were established by gel chromatography in Sephadex G-200. High and low molecular inhibitors were found in 19S and 4S serum fractions. Highly purified preparations of a2-macroglobulin, transferrine and albumin were isolated by a combination of methods of salt precipitation, gel chromatography on Sephadex G-100, G-200 and ion exchange on DEAE-Sephadex A-50. Heating sera resulted in a considerable increase of the antiviral activity of a2-macroglobulin and transferrine and a reduction ...
Brinsko SP, Ignotz GG, Ball BA, Thomas PG, Currie WB, Ellington JE.To compare the electrophoretic patterns of proteins synthesized and secreted by oviductal epithelial cell (OEC) explants obtained from young, fertile and aged, subfertile mares. Methods: Young, fertile (n = 5; 2 to 7 years old) and aged, subfertile (n = 5; 17 to 24 years old) mares. Methods: 2-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and computerized densitometry. Results: Variation in the synthesis and secretion of polypeptides from young, fertile mare OEC (YOEC) and aged, subfertile mare OEC (AOEC) was evidenced by differences in the intensity of radiolabeled pol...
McCool CJ, Gilfedder J.This study explores a rare case where an equine disease was found to be caused by Salmonella anatum, an organism typically associated with cattle, in a week-old foal and its […]
Noschka E, Moore JN, Peroni JF, Lewis SJ, Morrow JD, Robertson TP.Inflammation and vascular dysfunction occur concurrently during the prodromal stages of equine laminitis. The aim of this study was to provide insights into the role that thromboxane and isoprostanes may play in the development of black walnut heartwood extract (BWHE)-induced laminitis. Horses were divided into two groups, either control or BWHE-administered horses. Plasma concentrations of thromboxane increased transiently after administration of BWHE and coincided with the nadir in white blood cell counts, whereas plasma concentrations of iso-prostaglandin PGF(2alpha) (iso-PGF(2alpha)) did n...
Kidd JA, Dyson SJ, Barr AR.Intratendonous infection in the absence of any clinical evidence of a wound has not, to our knowledge, been described previously in horses. This paper reports the clinical features, diagnostic techniques. treatment and outcome in 5 cases of septic flexor tendon core lesions. This condition is characterised by seven lameness and ultrasonographic evidence of a central intratendonous anechoic core lesion which may enlarge rapidly.
Pinkowski W, Mohr E, Krzywanek H.During training, in 10 trotters, blood samples from the vena jugularis were taken before and after a heat with 80% of maximum capability as well as in the recovery period. Lactic acid concentration and pH-value, haematocrit and haemoglobin content, as well as protein concentration and osmolality were measured. With the exception of protein concentration, the time course of the values during the recovery could be described by simple mathematical models (biexponential or exponential equations). Only in the case of blood lactate concentration, the basal value was not yet achieved 120 min after th...
Giese C, Gerber V, Howald M, Bachmann I, Burger D.In order to investigate stress responses of horses in walkers with and without electricity, 12 horses were trained during 3 weeks in a horse walker with and without the use of electricity (3.7 kV). To evaluate the stress response, cortisol levels in the blood were measured, the heart rate was monitored using the Polar® system and the behaviour was evaluated. Neither the cortisol levels nor the heart rates showed any relevant statistically significant difference between horses moved in the horse walker with or without the use of electricity. The highest cortisol levels and heart rates were rec...
Ros A.A case of a cystic calculus in a pony mare is described. In this case an urethro-sphincterostomy accomplished removal of a 362 g calculus with dimensions of 9 x 7 cm without any complications after surgery.
Strömberg B.Thermography is the pictorial representation of infra-red (IR) emission from the surface of an object. IR emission from biological surfaces originates from two principal sources, circulation and metabolism, which are interdepen-dent. Changes in IR emission as recorded by thermography were correlated to changes in local blood circulation (BrAnemark & Nilsson 1969) and to changes in '33Xe disappearance rate (Stromberg & Norberg 1971). In 1969 Stromberg & Tufvesson, using microradiography, demonstrated that there were vascular changes in the superficial flexor tendon (SFT) even before clinical si...
Uehara N, Sawazaki H, Mochizuki K.The area of the largest transverse section and the number of muscle fibres in a unit sectional area (1 mm2) were examined in 8 trunk and 12 extremity muscles of young and adult 16 light horses and 8 ponies. It was found that the area of the largest transverse section was enlarged and the number of muscle fibres in a unit area was decreased, with the advance in age. This result suggests that the development of muscle volume does not depend on the increase in the number of fibres, but depends on the hypertrophy of each muscle fibre.
Heinrich B.This research article corrects a common misconception about the energy metabolism in horses during short sprinting and long-distance running events, emphasizing that short sprints are primarily powered by anaerobic activity, […]
Gastal EL, Donadeu FX, Gastal MO, Ginther OJ.The echotextural changes occurring in the follicular wall in association with deviation in diameters were studied in 8 pony mares. Echotextural changes could be useful as a reference point for future studies of the follicle-selection phenomenon. Follicles were examined daily by transrectal ultrasound from 3 d before to 3 d after the beginning of deviation (Day 0). The following echotextural end points were recorded based on a scoring or percentage system: 1) thickness of granulosa, 2) echogenicity of granulosa, 3) prominence of an anechoic layer located beneath the granulosa, and 4) extent of ...
Przewoźny M, Senderska-Płonowska M, Rząsa A, Wierzbicki H, Borkowski J, Swagemakers JH, Żak-Bochenek A, Stefaniak T.Arthroscopy and splint bone removal are the common orthopedic procedures in horses. Estimation of the dynamics of acute phase proteins in postoperative monitoring seems to be interesting diagnostic approach. The aim of the study was to investigate changes in the concentrations of plasma inflammatory markers-fibrinogen, haptoglobin, and protease inhibitors-following orthopedic surgery in horses. The study involved 114 horses, divided into two study groups undergoing: arthroscopy (41 horses) and splint bone removal (13 horses). The control group consisted of 60 healthy horses. The blood was coll...
Coggins L, Auchnie JA.Equine infectious anemia (EIA) has been enzootic in Hong Kong since the end of World War II. In 1972, a serologic survey of the horses at the Hong Kong Jockey Club indicated 23% prevalence of EIA. Disease control measures were instituted, and the spread of infection was reduced. In 1976, the prevalence of EIA was believed to be sufficiently low to implement procedures for eradication of EIA from all horses in Hong Kong. A correlation between EIA and poor performance of racehorses was demonstrated.
Bastianello SS, Nesbit JW.The pathological features of biliary atresia in a foal are described. A 4-week-old American Saddler foal was presented for autopsy following an illness characterised by clinical features indicative of hepatic failure. The significant macroscopical lesions occurred in the liver which was extremely enlarged, mottled in appearance and indurated. Bile stasis was evident. Lobular distinction was absent and on sectioning, large bile ducts were absent. A moderate ascites, hydrothorax and hydropericardium and a mild anasarca and intermuscular oedema accompanied the hepatic lesion. The diagnosis of bil...
Luna SP, Taylor PM.Cannulation of the pituitary effluent in horses is a useful method for investigating the release of pituitary hormones in loco (Irvine and Alexander 1987). Adrenocorticotropic hormone (ACTH) and arginine vasopression (AVP) concentrations in plasma collected from the intercavemous sinus, which receives all the pituitary outflow, were several times greater than those measured in peripheral plasma (Redekopp et at 1986). However, no studies evaluating the pituitary contribution to endogenous opioid secretion have been reported in the equine species. Cerebrospinal fluid (CSF) directly reflects CNS ...