Veterinary care in horses encompasses the medical and preventive measures taken to maintain and improve the health and well-being of equine patients. It includes a wide range of practices such as routine health examinations, vaccinations, dental care, parasite control, and management of injuries and diseases. Veterinary care also involves diagnostic procedures, surgical interventions, and therapeutic treatments tailored to the specific needs of horses. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of equine veterinary care, including advancements in diagnostic techniques, treatment protocols, and health management strategies to support the well-being and performance of horses.
Blikslager AT, Roberts MC.To assess the ability of clinicians to predict the site and type of lesion as well as outcome in horses with colic. Methods: Prospective case study. Methods: 139 horses admitted for evaluation of signs of colic. Methods: Six interns and residents examined horses with colic and predicted the segment of intestine that was affected, the type of lesion, and whether the horse would survive to discharge. Accuracy of prediction of site and type of lesion and survival prediction was compared between the first and second halves of the year, using chi 2 analysis and 95% confidence intervals on sensitivi...
Sojka JE, Levy M.This article outlines strategies on how to approach equine endocrine disorders based on clinical signs and clinical pathologic data. In the 1987 Veterinary Clinics of North America: Equine Practice article on evaluating equine endocrine function, Beech stated that the numbers of hormonal assays available to use in horses was limited. Unfortunately, not much has changed since then. With the advent of convenient assay kits for many hormones and cofactors available in human medicine, it is possible to submit samples to laboratories for measurement of a wide range of endogenous substances. Caution...
Swiderski CE, McClure JJ.The immune system is a complex interactive network. Defects in its function can be characterized broadly as being the result of actual deficiencies in the network or misdirection of normal immunologic functions. The assays that are available to detect deficiencies in the immunologic network barely scrape the surface of the possibilities. These assays primarily evaluate humoral immune function, but undetected defects in innate and cellular immunity are sure to exist. Although assays of humoral immunity have allowed the characterization of a number of immunodeficiency syndromes in horses, closer...
Baxi MK, Efstathiou S, Lawrence G, Whalley JM, Slater JD, Field HJ.Neural tissues from specific pathogen-free ponies that had been experimentally infected with equine herpesvirus 1 (EHV-1) were analysed by in situ hybridization. Digoxigenin-labelled EHV-1 BamHI fragments spanning almost the entire EHV-1 genome were hybridized to RNA in tissue sections from latently infected trigeminal ganglia. The BamHI E fragment detected EHV-1 RNA antisense to gene 63 (HSV-1 homologue ICP0) in a small number of neurons. Sixteen other BamHI fragments gave negative results in 20 sections tested with each fragment. Latency associated transcripts (LATs) were localized to the ne...
Galey FD.In most competent veterinary diagnostic laboratories, analytical findings are interpreted by the veterinary toxicologist to determine the significance of the finding in view of historic, clinical, and pathologic findings. A veterinary toxicologist also will provide consultation about possible toxic rule-outs for a case, treatment of affected animals, and prevention of additional cases. Once all of the information is available, a complete summary of the findings can be provided to the client. When the procedures outlined are followed, including a systematic approach to collecting all the eviden...
Kawcak CE, Baxter GM, Getzy DM, Stashak TS, Chapman PL.To measure arterial and venous blood gas, coagulation, and fibrinolysis variables in blood from isolated segments of control and ischemic large colons for the purpose of identifying variables for rapid, indirect assessment of colonic mucosal injury. Methods: Variables were determined at specific intervals during the 4-hour study (3 hours of ischemia and 1 hour of reperfusion). Methods: Seven clinically normal horses between 2 and 15 years old. Methods: Horses underwent laparotomy and occlusion of the lumen and vasculature of the mid-portion of the pelvic flexure of the large colon. During isch...
van der Kolk JH, Wisse H, van Dijk S.A 20-year-old Arab crossbred gelding was examined because it had apparently suffered an overstimulation of the parasympathetic nervous system for three hours. The clinical signs consisted of hypersalivation, profuse sweating, maximal miosis, fasciculation of the muscles and lateral recumbency in combination with continuous convulsions without diarrhoea. The horse's plasma pseudocholinesterase activity was approximately 10 per cent of normal. It responded well to 10 mg atropine and 50 mg diazepam administered intravenously.
Jones JH, Carlson GP.The metabolic power required for sustained exercise in the horse is proportional to running speed. Moderately fast speeds require substantial energy expenditure and result in the generation of a massive metabolic heat load. Quantitative estimates of energy expenditure and heat production of horses at various running speeds were developed using empirically derived data from treadmill studies. Total metabolic power represents the sum of aerobic power indicated by the rate of oxygen consumption and net anaerobic power indicated by the rate of plasma lactate accumulation. These data were applied t...
Hurley JR, Begg AP.A trial was conducted on a Thoroughbred stud to determine whether or not the administration of anti-Rhodococcus equi hyperimmune plasma would reduce the prevalence of R equi pneumonia (rattles) in foals born in the 1992 horse breeding season. Hyperimmune plasma was administered to 34 foals; another 57 foals were untreated. There was no significant difference in the number of transfused foals developing R equi pneumonia compared with the untreated foals. The time required for recovery from pneumonia between the 2 groups was not significantly different.
Ijaz A, Ducharme R.Stallion semen was diluted in five different extenders (dimitro-poulus onze (Dimitro's), Kenney's modified tryode (Kenney's), modified INRA82 (INRA82), egg yolk-citrate-taurine (Citrate) and EZ-Mixin) and evaluated for motility after cooling and storage at 5 degrees C for 0, 24, 48, 72 and 96 h. EZ-Mixin extender was used as control while 70 and 100 mM of taurine were added to Dimitro's, Kenney's and INRA82 to study its effect under conditions of storage at 5 degrees C and varying processing modifications. Motility in INRA82 was 57.0, 58.4, 61.1, and 56.1% after 24, 48, 72 and 96 h, respective...
Frankeny RL, Wilson DA, Messer NT, Campbell-Beggs C.Jejunojejunal intussusception occurred after jejunal resection and stapled functional end-to-end anastomosis in two pony mares. In both mares, the lead point of the intussusception was the stapled functional end-to-end (FEE) anastomosis. The stapled free ends of jejunum were oversewn with an inverting suture pattern. A possible explanation for development of the intussusception was the acute angle created in the intestine by the FEE anastomosis. This angulation may have impaired flow of ingesta causing motility changes that predisposed the site to intussusception. Because the oversewn blind in...
Valdez RA, DiPietro JA, Paul AJ, Lock TF, Hungerford LL, Todd KS.The bioequivalence of Strongid C and generic pyrantel tartrate was determined in a controlled study using 30 horses with naturally acquired endoparasitic infections. Three horses were randomly allocated to each of ten replicates based on quantitative nematode and ascarid egg counts and fecal larvae culture results. Horses within each replicate were randomly assigned to one of three treatment groups. Horses in Treatment Group 1 received only oats; horses in Treatment Group 2 received generic pyrantel tartrate pellets (2.65 mg pyrantel tartrate kg-1) mixed with oats; horses in Treatment Group 3 ...
Vatistas NJ, Meagher DM, Gillis CL, Neves JW.Twenty-two horses were examined because of firearm injuries. Nine had been shot with .22-caliber bullets, 2 with BB pellets, 6 with buckshot, 1 with a .35-caliber bullet, and 1 with an airgun pellet. Injury was confined to the skin or skeletal muscles in 8 horses. Of these, 7 returned to their previous use. In 14 horses, injuries to additional structures were incurred, including the sinus and pharynx (n = 2), mandible (n = 1), tooth (n = 1), aorta (n = 1), eye (n = 3), tibia (n = 1), gastrointestinal tract (n = 3), joint (n = 1), and trachea (n = 1). The 3 horses that had only eye injuries wer...
Gibson KT, Burbidge HM.Three horses were presented for treatment of chronic infections of the digital flexor tendon sheath. Clinical signs included severe lameness, and heat, pain and swelling of the digital flexor tendon sheath. The horses were treated with surgical lavage of the tendon sheath, systemic and local antibiotics, and analgesics. In each case, resolution of the lameness occurred over weeks to months. Only one horse returned to athletic activity, while the other two became comfortable at pasture. Response to treatment in cases of chronic tenosynovitis may not be as rapid or complete as that reported for ...
Ragle CA, Schneider RK.Eleven mares and four mules were ovariectomized by a ventral abdominal laparoscopic technique. This approach required tilting the operative table about 30 degrees elevating the pelvis to allow observation of the ovaries. A triangulation technique with a single laparoscopic portal and four instrument portals was used. The ovarian pedicles were ligated and the ovaries were removed through a single enlarged instrument portal. Females ranged in age from 5 months to 18 years. Mean operative time was 44 minutes (range 20 to 90 minutes); mean operative time of the last seven animals was 26 minutes. S...
Silva RA, Arosemena NA, Herrera HM, Sahib CA, Ferreira MS.This paper reports an outbreak of trypanosomosis due to Trypanosoma evansi in horses of the Pantanal Mato-grossense region of Brazil. Forty-eight horses died (51% mortality) and abortion in one mare was recorded. The clinical signs observed were fever, anemia, conjunctivitis, edema of the legs and lower parts of the body, progressive weakness, loss of condition, and loss of appetite. The diagnosis was confirmed by morphological and biometrical studies.
Schroter RC, Marlin DJ.There is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3-day-events in environments where there is likely to be a high level of radiation added to high ambient temperatures and relative humidity; the presently used FEI 'Comfort Index' is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as: WBGT = 0.7Twb + 0.3...
Blikslager AT, Bristol DG, Bowman KF, Engelbert TA.To determine the feasibility of performing a single-incision loop colostomy for treatment of grade-3 rectal tears in horses. Methods: Retrospective case series. Methods: Seven adult horses with grade-3 rectal tears. Methods: A single-incision loop colostomy was performed with horses under general anesthesia (n = 6) or while restrained in standing stocks (n = 1). The rectal tear was lavaged via an endoscope. The colostomy was resected after the rectal tear healed. Results: Rectal tears ranged from 4 to 10 cm in diameter and were > 25 cm proximal to the anus. All horses survived colostomy surger...
Haywood PE, Teale P, Moss MS.Thoroughbred geldings were fed racehorse cubes containing a predetermined concentration of theobromine in the form of cocoa husk. They were offered 7 kg of cubes per day, divided between morning and evening feed, and food consumption was monitored. Urinary concentrations of theobromine were determined following the consumption of cubes containing 11.5, 6.6, 2.0 and 1.2 mg per kg of theobromine, to verify whether or not such concentrations would produce positive urine tests. Pre-dose urine samples were collected to verify the absence of theobromine before each experiment. It became apparent fro...
Ward A, Stephen K, Argo C, Watson C, Harris P, Neacsu M, Russell W, Grove-White D, Morrison P.During the lockdown phase of the COVID-19 pandemic, equestrian stakeholders faced a dilemma whereby they were required to balance caring for the welfare of horses with adapting to the restrictions imposed to protect public health. The present study investigated the impact of the pandemic on the wellbeing of a sample of industry stakeholders, including horse owners, equine veterinarians, farriers and welfare centre managers ( = 26) using a qualitative methodology. Findings from the interviews indicated that the mental health and wellbeing of veterinarians and horse owners was negatively affecte...
Sellon DC.FPT of immunoglobulin in foals is the commonest form of acquired immunodeficiency in horses. FPT predisposes foals to bacterial infections and septicemia and easily is preventable and treatable if breeding farms and veterinarians are attentive to optimum foaling management practices. Other forms of acquired immunodeficiencies are uncommon in horses, although immune function may be transiently suppressed by a wide variety of drugs, infections, or other conditions. As immunologic testing becomes more sophisticated and more readily available to equine practitioners, acquired immunodeficiencies ar...
The Journal of heredityJuly 1, 1987
Volume 78, Issue 4 248-250 doi: 10.1093/oxfordjournals.jhered.a110376
Bowling AT.Blood type analysis of 29 foals in a paternal half-sib family verified linkage of five LGII loci (Es, E, To, Gc, Al). Population and parentage data from other tobiano-spotted horses suggested conservation of a tightly linked (To:GcS:AlB) marker complex.
Cannon JH, Grant BD, Sande RD.Development of cysts in the equine paranasal sinuses is probably a congenital disease; however, signs may not appear for several years. In 4 cases, clinical signs were observed when fluid accumulation within the cysts resulted in nasal discharge or facial swelling, or when secondary infection occurred. Treatment required surgical removal of the lining membrane and other involved tissues. Postoperative care included lavage of the sinuses and systemic antibiotic therapy.
Goehring LS, Sloet van Oldruitenborgh-Oosterbaan MM.Equine protozoal myeloencephalitis (EPM) was diagnosed in a Dutch Warmblood gelding a few months after its export to the United States. The horse came back and was treated here. Additionally, an overview of the disease complex 'EPM' is given. Mode of infection, diagnosis of disease and its differential diagnoses, and general therapeutic options are presented. Although EPM due to infection with Sarcocystis neurona in Europe seems restricted to those horses that return or are imported from North America, the possibility of future cases of EPM caused by an infection with Neospora spp. is briefly ...
Matheis FL, Birkmann K, Ruetten M, Pot SA, Spiess BM.A 10-year-old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an e...
Vatistas NJ, Wright IM, Dyson SJ.Forty-eight horses with osteochondritic lesions of the femoropatellar joint were treated, 23 of them by an arthrotomy and 25 by arthroscopy. Follow-up information was obtained from either the owner or the referring veterinarian by telephone inquiry. There were no statistical differences between the groups of horses undergoing the two procedures with regard to age, sex, breed, the involvement of one or both limbs, the size of the lesion, and the duration of either the surgery or anaesthesia. However, the horses treated by an arthrotomy spent 14.5 days in hospital after the operation whereas tho...
Weers JG, Maki AH.Triplet-singlet energy transfer has been studied in the complex formed between auramine O (AO) and horse liver alcohol dehydrogenase with optically detected magnetic resonance (ODMR) spectroscopy. The results show that Trp-15 and Tyr residues transfer triplet energy mainly by a trivial process, whereas Trp-314 transfers triplet energy by a Förster process with two observed lifetimes at 77 K of 170 and 50 ms. The different Förster energy-transfer lifetimes are ascribed either to quenching of the two Trp-314 residues of the dimer by a single asymmetrically bound AO or to two distinct conformat...
Klide AM.Fifteen horses with chronic back pain for 1/2 to 9 years, who could not function normally, who did not obtain any lasting improvement from other previous treatments, were treated with acupuncture. The treatments were 20 minutes of manual acupuncture. The average number of treatments was 7.9 times administered at weekly intervals. After the acupuncture treatments were completed, 13 of the 15 horses were able to function normally.
Saliou G, d'Ablon X, Théaudin M, Saliou T, Bourassi S.Performing a brain computerized tomography scan (CT scan) on a foal requires specific equipment and anesthesia for large animals. However, the information obtained may demonstrate lesions responsible for the neurological deficits. Especially, CT scan findings may help to understand a mechanism of cerebral ischemia. Indeed, categories of cerebral ischemia are divided in three types: territorial infarctions (downstream of the territory of an artery), watershed infarctions (slow-flow at the junction of two arterial territories), and lacunar infarctions (small-vessel occlusions). Hypersensitivity ...
ter Braake F, Hesselink JW, Jonker FH.An eleven year old warmblood mare was referred to Dierenkliniek Emmeloord because of recurrent cyclic behavioral problems. A standing bilateral laparoscopic ovariectomy was performed. Due to this minimal invasive technique a quick return to training was possible.
Trigo P, Muñoz A, Castejón F, Riber C, Hassel DM.We describe a fatal case, in which a horse suffered a fall and as a consequence, rib fractures. Diagnosis was made postmortem and the horse died without showing clear signs of respiratory dysfunction. The retrospective reports of injuries can be important to reduce these traumatic events and to avoid fatalities. Nous décrivons un cas mortel, chez un cheval ayant subi une chute qui a causé des fractures des côtes. Un diagnostic a été posé à l’autopsie et le cheval est mort sans avoir montré de symptômes évidents de troubles respiratoires. Les rapports rétrospectifs de blessures pe...
Vasey JR, Julian RJ.The distal 30 to 40 cm of the ileum cannot be exteriorized through a midline laparotomy incision because of its close anatomical association with the base of the caecum. A method was developed to deal with those cases where this segment of small intestine was involved in an avascular, necrotic process and therefore required resection. The technique involves inverting the distal stump of ileum into the lumen of the caecum and then performing a routine ileocaecal or jejunocaecal anastomosis. This avoids the risk of peritonitis if a Parker-Kerr oversew of the necrotic ileal stump should dehisce. ...
Doyle AJ, MacDonald VS, Bourque A.A 12-year-old gelding was diagnosed with recurrent lymphoma in multiple cutaneous sites. A highly invasive preputial mass caused urethral obstruction. The horse was treated with surgery and chemotherapy consisting of lomustine (CCNU) and prednisolone. The treatment was well-tolerated and effective. This is the first reported use of lomustine (CCNU) in a horse for the treatment of equine lymphoma. Utilisation de lomustine (CCNU) dans un cas de lymphone cutané équin. Un hongre âgé de 12 ans a été diagnostiqué avec un lymphome récurrent sur plusieurs sites cutanés. Une masse préputiale ...
Dietz HH.25 horses were subjected to the D(+)-xylose absorption test. 1 gram of D(+)-xylose/kg bw. was administered orally. Based upon the shape of the absorption curves the 25 patients were divided into four groups. Group 1 11 patients with a normal absorption curve (Figure 3) Group 2 5 patients with a flat absorption curve (Figure 4) Group 3 3 patients with a flat absorption curve (Figure 5) Group 4 7 patients with an intermediary type of absorption curve (Figure 6). Administration of sodium chloride in equimolar concentrations did not improve the absorption of D(+)-xylose. 73 per cent of the horses ...
Welschen SE, de Bruijn CM, Sloet van Oldruitenborgh-Oosterbaan MM.The short- and long-term results of admission to the 'Neonatal Intensive Care Unit' (ICU) at the Department of Equine Sciences of the Utrecht University were evaluated. The patients were categorized, based on specific criteria, into different groups: 'Sepsis', 'Pneumonia', 'Enteritis', 'Asphyxia', 'Premature', 'Isoerythrolysis', and 'Equine herpes virus (EHV)'. The survival rate and mean duration of hospitalization were determined for each group. The venous blood variables at admission were compared for 'surviving' and 'non-surviving' foals within groups, between groups, and for the overall gr...
Cheramie HS, O'Ggrady SE.There are many different commercially available hoof repair/adhesive products. The application of these products in the treatment of various foot conditions is continuing to evolve based on sound medical and farriery principles as well as imagination. Successful application of these products depends largely on using proper hoof wall preparation and adhesive application techniques. Success also depends on a realistic expectation of the final outcome when accounting for the physical limitations of the adhesive products and the underlying hoof problem. Our results with these techniques have been ...
Haynes PF.Persistent dorsal displacement of the soft palate was diagnosed in 2 Thoroughbred horses examined because of decreased exercise tolerance and a respiratory noise during strenuous exercise. The persistent dorsal displacement of the soft palate was caused by an epiglottis that was approximately 2/3 normal size, and thus was incapable of maintaining the soft palate in a normal subepiglottic position. Contrast pharyngography suggested a primary epiglottic abnormality. Visual assessment of the lesion was accomplished by exploratory ventral laryngotomy and endoscopy of the oropharynx per os. Surgica...
Silver IA, Jeffcott LB, Rossdale PD.The British Equine Veterinary Association (BEVA) was established in 1961 and launched the Equine Veterinary Journal (EVJ) in 1968. This review outlines some of the major advances in equine science and practice that have occurred in that time and the role played by the Journal in facilitating those developments.
Torkelson J.A quarter horse gelding with intermittent colic was diagnosed with a perirectal abscess and dyschezia. Rectal ultrasonography identified a multiloculated, fluid-filled mass. A perirectal abscess was diagnosed when the mass ruptured and drained into the rectum. The abscess was treated successfully with warm soapy water enemas and trimethoprim and sulfamethoxazole.
Reijerkerk EP, Veldhuis Kroeze EJ, Sloet van Oldruitenborgh-Oosterbaan MM.Equine sarcoidosis is a rare disorder usually characterized by exfoliative dermatitis, moderate to severe wasting, and sarcoidal granulomatous inflammation of multiple organ systems. It has an unknown aetiopathogenesis. The condition is not related to equine sarcoid. This case report describes generalized cutaneous and systemic sarcoidosis in an 11-year-old Trakehner mare (case A) and in a 7-year-old Dutch Warmblood gelding (case B). Case A was presented with cutaneous sarcoidosis on the head and body and was diagnosed on the basis of histological examination of skin. Case B presented with mul...
Caudron I, Miesen M, Grulke S, Vanschepdael P, Leroy P, Serteyn D.The authors used a new radiological method to assess asymmetrical articular compression of the interphalangeal joints. This method was based on the measurements of 3 angles obtained on dorsopalmar radiographs. Variations of these angles were studied during experimental asymmetrical bearing on unshod feet. It was concluded that 2 angles were interesting parameters to assess asymmetrical articular compression and to define the position of the phalanx in the horny box. Furthermore, variations of these angles induced by experimental asymmetrical bearing were compared without shoe, with a standard ...
Gough R, McGovern K, Bladon B, De Oliveira F.This report describes two cases of spontaneous small intestinal evisceration via normally inserted umbilical stumps, without abdominal wall trauma. Both cases occurred immediately following uneventful parturition. The authors believe that these represent cases of umbilical cord herniation. This is a well-recognised condition in humans, but has not been previously described in equines. One foal died before veterinary intervention. The second foal underwent a jejunal resection with end-to-end anastomosis and survived to successfully race. This report describes a previously unrecognised condition...
Stanbouly D, Besmer AV, Chuang SK.The purpose of our study is to assess the severity of craniomaxillofacial injuries from horseback-riding accidents. Methods: This is a 20-year retrospective cross-sectional study of the National Electronic Injury Surveillance System. Injuries from the activity of horseback-riding were included if they occurred in the craniomaxillofacial complex. Study predictors were derived from both patient and injury characteristics. The study outcome was the presence or absence (probability) of hospital admission from the emergency department. A multiple logistic regression model was created to model the o...
Wasyl Z.1. Horse liver acid phosphatase was separated into two partially purified fractions differing in molecular weight (enzyme I about 100 00, enzyme II about 25 000). 2. Enzyme I was separated into several subfractions by DEAE-cellulose chromatography and isoelectric focusing. 3. Molecular weight, sedimentation coefficient and effective molecular radii were determined for acid phosphatases I and II by gel filtration and density-gradient centrifugation.
Nanda BS, Getty R.The arteria intercarotica caudalis was observed to be present in the dog, horse and cat but was reticulated in the case of cattle, sheep, goat, and pig. The latter structure was a homologue of the former and represented an important intercarotid communication present in most of vertebrate.
Gehring R.The Veterinary Pharmacovigilance Centre received 59 reports of suspected adverse drug reactions during the period January 1998 - February 2001. The number of reports received increased after the establishment of a formal procedure for recording and responding to reports. The number of reports received per species was: dogs 19, cats 15, cattle 7, sheep/ goats 6, chickens 4, pigs 3, horses 2 and giraffe 1. Many different types of adverse reactions were reported, including lack of efficacy, hypersensitivity, inappropriate use of products by non-veterinarians, known adverse effects and adverse eff...
Guglick MA, MacAllister CG, Chandra AM, Edwards WC, Qualls CW, Stephens DH.Mercury toxicosis by ingestion was diagnosed in a 3-year-old Quarter Horse mare with a history of anorexia and signs of abdominal discomfort. Ten and 9 days prior to admission, an inorganic mercuric blistering agent has been applied for topical treatment of dorsal metacarpal disease. At referral, signs of depression, dependent edema, pollakiuria, nonproductive cough, and oral ulceration were noticed. Laboratory data were consistent with renal dysfunction. Mercury content of blood and urine was high, confirming the diagnosis. The horse responded to intensive care, consisting primarily of IV flu...
Johnson CB, Adam EN, Taylor PM.Hypoxaemia commonly develops during general anaesthesia and in the recovery period in horses. The Hudson demand valve has been used to increase arterial PO2, but it has been found to increase airway resistance considerably when used during spontaneous ventilation. This paper evaluates a modification of the valve designed to reduce this resistance. The effects of the valve and its modification on arterial oxygen (PaO2), and carbon dioxide (PaCO2) tensions were evaluated in four ponies anaesthetised by a total intravenous technique. The valve increased PaO2 from 8.3 +/- 1.1 to 32.7 +/- 7.6 kPa d...
