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.
Dolvik NI.Of 508 four-year-old coldblooded trotters examined for carpitis, 135 (27%) had the condition. Thirty horses had unilateral carpitis on the left frontlimb, 52 on the right frontlimb and 53 had bilateral carpitis. Of these horses, 105 were stallions, 135 were geldings and 269 were mares. The prevalence of carpitis in these three groups was 25%, 25% and 28%, respectively. Information was obtained on the training regimes in four periods of the life of 378 horses. The odds ratios for the training variables were of the same order in all four periods. In logistic regression analyses on the training v...
Art T, Votion D, McEntee K, Amory H, Linden A, Close R, Lekeux P.Two randomly distributed groups of thoroughbred horses were compared during a 12-week period for their cardio-respiratory and metabolic adjustment to strenuous exercise, training and detraining. The horses were trained following the same standardized schedule and were regularly investigated using standardized treadmill exercise tests (SET) of increasing speed. After the first SET and during the whole experimental period, a group of 6 horses received a probiotic (Bioracing) once a day while a group of 5 horses received a placebo. All other conditions were similar for both groups. During each SE...
Agius CT, Studdert MJ.This chapter describes the molecular and biological properties of equine herpesviruses (EHV)2 and EHV5. It highlights advances in the study of EHV2 and EHV5. The reclassification of EHV2 and EHV5 as gammaherpesviruses rather than betaherpesviruses has profound implications for future approaches to the study of the two equine herpesviruses. The chapter places emphasis on a comparison between the properties of EHV2 and EHV5 and those of other gammaherpesviruses, especially Epstein-Barr virus (EBV), which is the causative agent of infectious mononucleosis/glandular fever in humans. Studies of the...
Xiao L, Herd RP.Prevalence and infection patterns of Cryptosporidium and Giardia infections in horses were studied by a direct immunofluorescence staining method. Faecal examinations of 222 horses of different age groups revealed Cryptosporidium infection rates of 15-31% in 66 foals surveyed in central Ohio, southern Ohio and central Kentucky, USA. Only 1 of 39 weanlings, 0 of 46 yearlings, and 0 of 71 mares were positive. Giardia infection was found in all age groups, although the infection rates for foals were higher (17-35%). Chronological study of infection in 35 foals showed that foals started to excrete...
Cahill CM, Van der Kolk H, Goode JA, Hayden TJ.Highly purified and well-characterised preparations of equine prolactin and growth hormone from equine pituitary glands were employed to set up highly sensitive and specific homologous radioimmunoassays (RIA) for the measurement of hormone in horse plasma. The limit of sensitivity of the GH RIA was 1.2 ng/ml with mean intra- and inter-assay coefficients of variation (CV) of 6.6 and 10%, respectively. The sensitivity of the equine prolactin (ePRL) RIA was 0.5 ng/ml with mean intra and inter-assay CV of 9.1 and 15.6%, respectively. Dose-response curves of a crude pituitary gland extract and plas...
Arrighi S, Romanello MG, Domeneghini C.The epithelium that lines the ductuli efferentes in the horse, donkey and mule has been examined by electron microscopy. The epithelium consists of columnar ciliated and non-ciliated cells. Lymphocytes and macrophages are also present, together with cells that are rich in lipofuscin. These 'lipofuscin-rich' cells are a peculiar feature of the excurrent ducts of Equidae and are characterized by a large number of highly heterogeneous residual bodies. The general morphology of the epithelium and, in particular, of the non-ciliated cells implies that the epithelium is involved in the absorption an...
Dippert KD, Jasko DJ, Seidel GE, Squires EL.Embryo recovery per ovulation has been shown to be lower in superovulated mares than in untreated controls. The objectives of this study were to 1) determine whether follicles stimulated with superovulatory treatment ovulate or luteinize without ovulation, 2) determine fertilization rates of oocytes in oviducts of superovulated and control mares, and 3) evaluate viability of early stage embryos from superovulated and control mares when cultured in equine oviductal cell-conditioned medium. Cyclic mares were randomly assigned to 1 of 2 groups (n=14 per group) on the day of ovulation (Day 0): Gro...
Häni H, Lang J, Ueltschi G.During archaeological excavations of the former knackers yard in Emmen (Canton Lucerne) skeletons and individual bones of more than 700 animals were recovered. 110 bone samples had lesions and were examined macroscopically and radiologically, 100 were from horses, 9 from dogs and only one from cattle. According to morphological and etiopathogenetical criteria, lesions are presented in the following groups: tooth irregularities (10), degenerative changes in bones and joints due to overload and aging (80), trauma and infection (10), other lesions (10). Over 80% of pathological bone samples prese...
Murray A, Cottrell DF, Woodman MP.Equine grass sickness (EGS) is a pan-dysautonomia of horses that involves central and peripheral neuronal degeneration and ultimately depletion. This is the first reported functional study on the motility of equine intestine taken immediately post mortem from horses with EGS. Strips of smooth muscle from the small intestine of healthy and EGS-affected horses were suspended in an organ bath and their motility was measured isometrically. The activity of the cholinergic system was studied. Physostigmine enhanced the motility of all muscle strips. Tissues taken from horses suffering from acute gra...
Leder L, Bosshard HR.It has long been known that antibodies to cytochrome c can distinguish between closely sequence-related cytochromes c. Because the 3-D-structure of the polypeptide chain is virtually identical among eukaryotic cytochromes c, antibody specificity is directed against amino acid substitutions within a common polypeptide folding pattern. The question arises if the specificity is observed at the level of the 3-D-structure (conformational epitopes) and/or at the level of the primary structure (sequential epitopes). Using rabbit sera to horse cytochrome c, we show that discrimination against the host...
Vanderwall DK, Woods GL, Weber JA, Lichtenwalner AB.The objective of this study was to test the hypothesis that intrauterine administration of prostaglandin E(2) (PGE(2)) or estradiol-17beta (E-17beta) would prolong CL function in nonpregnant mares. Nonpregnant mares were continuously infused with 240 mug/d of PGE(2), 6 mug/d of E-17beta, or vehicle (sham-treated) on Days 10 to 16 post ovulation (ovulation = Day 0), using osmotic minipumps surgically placed into the uterine lumen on Day 10 (n = 11 per group). Nonpregnant and pregnant mares served as negative and positive controls, respectively (n = 11 per group). Mares were defined as having pr...
Lin HC, Wallace SS, Robbins RL, Harrison IW, Thurmon JC.In 4 mares suffering from dystocia, general anesthesia was induced with xylazine (1.1 mg/kg, IV) and ketamine (2.2 mg/kg, IV) and maintained with continuous intravenous infusion of ketamine (2 mg/ml), xylazine (0.5 mg/ml) and guaifenesin (50 mg/ml) in 1 L of 5% dextrose. The duration of the procedure of these mares were 40, 45, 180, and 35 minutes, respectively. For procedures required more than 1 hour (Mare 3), the dose of ketamine and xylazine in the mixture was reduced to 1 mg/ml and 0.25 mg/ml, respectively. Average infusion rate of the mixture used to maintain anesthesia for each mare was...
Allen AL, Doige CE, Fretz PB, Townsend HG.A syndrome of neonatal foals characterized by hyperplasia of the thyroid gland and concurrent musculoskeletal deformities (TH-MSD) has been described in western Canada and may be increasing in incidence. In an attempt to improve recognition and understanding of this syndrome, 2946 records of equine abortuses, stillborns, and dead neonatal foals were examined to determine the laboratory involved, the year and month of submission, the breed and sex of the fetus or foal, the type of perinatal loss, the length of gestation, and whether or not the submission had evidence of a lesion of the thyroid ...
Dalefield RR, Palmer DN.Thyroid tumours have been described as "moderately common" in horses, but diseases associated with them are rare and the actual incidence has not been reported. A survey of thyroids from 29 horses aged 12 to 32 years revealed gross lesions in 11 animals, all older than 17. Most lesions were microfollicular adenomas. There was no evidence that the horses suffered from long-standing iodine deficiency or diffuse hyperplasia. Adenomas were more common than hyperplastic nodules and it is unlikely that the former arose from the latter. One thyroid adenocarcinoma was discovered. Progression from thyr...
Todhunter RJ, Wootton JA, Altman N, Lust G, Minor RR.Collagen type I and type II were purified from equine flexor tendon and articular cartilage, respectively. Equal amounts of these collagens were cleaved with cyanogen bromide, and 11 mixtures containing increasing proportions of type II collagen were separated in seven identical sodium dodecyl sulfate-polyacrylamide gels. The density of bands was measured in wet gels and the peak areas were used to form six ratios of peptide bands that had polynomial relationships with the known proportions of type I and type II collagen in the mixtures. Calibration curves for determining the proportion of typ...
Heiskanen ML, Hilden L, Hyyppä S, Kangasniemi A, Pirhonen A, Mäenpää PH.The first (1 to 3) sperm-rich fractions of the ejaculate were collected from 4 stallions using an open-ended vagina. The volume of the collected fractions was 12 +/- 8 ml with a density of 475 +/- 200 million spermatozoa/ml. Before freezing, the semen was diluted with a skim-milk based extender 1:1 to 1:8 (volume of semen: volume of extender), depending on the initial sperm concentration to achieve a final concentration of 100 million/ml. The total number of spermatozoa in an insemination dose ranged from 0.7 to 1 billion spermatozoa. Within 12 h after ovulation, 48 mares were inseminated in 7...
Nixon AJ, Cummings JF.Serial sections of bone and soft tissue from the metacarpophalangeal joints of 2 mature and 2 immature horses were evaluated for substance P immunoreactive sensory nerve fibers. Formalin-fixed specimens were sectioned, either nondemineralized or demineralized with formic acid or EDTA. Rabbit antiserum to substance P (SP) was used in the streptavidin-biotin-peroxidase complex method for immunolocalization of SP antigen, and staining with 3,3'-diaminobenzidine was used for permanent identification of SP fibers. Abundant sensory nerve fibers were identified in the joint capsule, synovial membrane...
Mills PC, Ng JC, Thornton J, Seawright AA, Auer DE.Four unfit thoroughbred horses were exercised on a treadmill twice, 5 weeks apart. Exercise consisted of stepwise increments in treadmill speed up to a maximum of 12 m s-1 and then maintained at this speed until the horses were fatigued. Two of the horses were administered phenylbutazone (4.4 mg kg-1) intravenously immediately before the first exercise period and the other two horses immediately before the second exercise period. Clinical observation revealed stiffness of gait and palpable soreness over the lumbar-sacral region in the horses 24 h after the exercise concluded. Mean plasma aspar...
Ghram A, Chabchoub A, Turki I, Boussetta M, Ibn Amor H, Ghorbel A.A seroepidemiological survey was realized in the Nord-Est Tunisia to study the prevalence of complement fixing and neutralizing antibodies to equine rhinopneumonitis and viral arteritis of horse, respectively. Four hundred sera were tested, using complement fixation reaction and seroneutralization test. The results show that 8.75% of sera have antibodies to viral arteritis and only 1.25% are positive for equine rhinopneumonitis.
Bowker RM, Sonea IM, Vex KB, Caron JP.Substance P (SP) immunocytochemistry and receptor autoradiography were used to define the innervation of the equine synovial membrane of joints equivalent to the wrist and knuckle of man. SP-immunoreactive fibers were mainly concentrated around blood vessels in the subsynovial layer, although not exclusively, while in the more distal joint, SP fibers were more frequently seen in the synovial surface layer. Iodinated SP receptor autoradiography studies revealed silver grain concentrations in the advential layer of blood vessels associated with the vasa vasorum, on the vascular endothelium and i...
Bowker RM, Rockershouser SJ, Vex KB, Sonea IM, Caron JP, Kotyk R.To determine whether the distal interphalangeal (DIP) joint directly or indirectly communicates with the navicular bursa (bursa podotrochlearis) and to identify sensory nerves in these synovial structures that might be desensitized by intra-articular injections of anesthetics, Evans blue dye in physiologic saline solution, Luxol fast blue dye with mepivicaine, or commercial latex was injected into the DIP joint (5 ml) or the navicular bursa (3 ml) of 152 digits obtained from horses or ponies at necropsy. The digits were frozen, cut with a band saw, and examined for distribution of dye or latex...
Hinchcliff KW, Kociba GJ, Mitten LA.Thrombocytopenia in horses may be idiopathic or secondary to chronic infectious or inflammatory diseases (eg, equine infectious anemia, lymphosarcoma), drug administration, bone marrow depression, myelophthisic disease, or disseminated intravascular coagulation. This report describes EDTA-dependent pseudothrombocytopenia in a horse. Platelet counts for blood containing EDTA were consistently less than reference range, but platelet counts of blood containing heparin were within reference range. When thrombocytopenia is diagnosed in horses without clinical evidence of a bleeding tendency, EDTA-d...
Friebe M, Schumacher S, Stahl J, Kietzmann M.This study investigated synovial concentrations of acetylsalicylic acid (ASA) and its metabolite salicylic acid (SA) in the equine fetlock joint following systemic administration of ASA. Salicylates were chosen because SA is the only nonsteroidal anti-inflammatory drug for which threshold levels exist for plasma and urine in equine sports. To avoid animal experiments, the study was conducted using an ex vivo model of the isolated perfused equine distal limb in combination with plasma concentrations obtained from literature.Salicylate concentrations in the joint were determined using microdialy...
Sperl C, Gerber V, Drießlein D, Klima A, Becher AM.Respiratory signs or more specifically severe equine asthma (SEA) is in some studies reported to be associated with decreased strongyle egg shedding. This association can be reproduced in a larger population of unrelated horses. The owners of 209 horses, on seven farms in Bavaria, were interviewed using, an in prior studies validated questionnaire. Horses were categorized into classes of the horse owner assessed respiratory signs index (HOARSI 1-4, unaffected to severely affected). In total, 1,035 fecal samples were analyzed between March 2011 and September 2014 using a modified McMaster proce...
Geor RJ, Lund EM, Weiss DJ.Retrospective review of CBC and serum chemical data from 124 horses admitted to the veterinary teaching hospital over a 9-month period (Feb 1, 1990 to Oct 31, 1990) indicated that 54 horses had echinocytosis (prevalence = 44%). In horses with echinocytosis, the most frequent diagnosis was colitis (23 horses; 43%). Odds ratios (measure of association) were calculated to determine the association of echinocytosis with specific hematologic and biochemical abnormalities. When evaluated in a multivariate model, low serum sodium concentration (< 136 mEq/L) was the only variable significantly associa...
Camacho-Rozo CA, Santos GO, Wenzen DP, Cousseau SB, Wronski JG, Argenta FF, Winter GHZ, Pavarini SP, Mattos RC.This report describes a case of sudden death of a pregnant miniature mare due to an acute ovarian hemorrhage leading to fatal hemoperitoneum. The miniature horse was a 12-year-old female, 60 days pregnant, with a body condition score of 7 (1-9), with a history of obesity and laminitis. Necropsy revealed hemoperitoneum due to an ovarian capsule rupture and hemorrhage after a physiological supplementary ovulation and luteinization. Ovarian rupture after ovulation is uncommon in mares.
Rozario C, Martínez-Sobrido L, McSorley HJ, Chauché C.Influenza A viruses (IAVs) are important respiratory pathogens of horses and humans. Infected individuals develop typical respiratory disorders associated with the death of airway epithelial cells (AECs) in infected areas. Virulence and risk of secondary bacterial infections vary among IAV strains. The IAV non-structural proteins, NS1, PB1-F2, and PA-X are important virulence factors controlling AEC death and host immune responses to viral and bacterial infection. Polymorphism in these proteins impacts their function. Evidence from human and mouse studies indicates that upon IAV infection, the...
Tahoun A, Elnafarawy HK, Elmahallawy EK, Abdelhady A, Rizk AM, El-Sharkawy H, Youssef MA, El-Khodery S, Ibrahim HMM.Diagnosis and treatment of ocular fungal infection in equine seems very challenging for owners and clinicians. The present study aimed to identify and characterize fungal species isolated from the eyes of clinically healthy and diseased equines (N = 100) from Dakahlia Governorate, Egypt. The work also involved morphological and molecular characterization of the major fungal species. In addition, correlations between the occurrence of isolated fungi and some of the potential risk factors were also investigated. Interestingly, the prevalence rate of ocular mycosis in all examined equines in the ...
Gilday RA, Wojnarowicz C, Tryon KA, Lohmann KL.A Canadian warmblood foal treated for septic polyarthritis was diagnosed with bilateral congenital renal dysplasia, hydronephrosis, and hydroureter at 2 weeks of age based on abdominal ultrasound and postmortem examination. Intermittent abdominal pain throughout the course of treatment was attributed to hydronephrosis and hydroureter. Un poulain Warmblood canadien traité pour une polyarthrite septique a été diagnostiqué avec de la dysplasie rénale congénitale bilatérale, de l’hydronéphrose et de l’urétérohydrose à l’âge de 2 semaines en se fondant sur une échographie abdomi...
Harrison LJ, May SA, Edwards GB.Over a period of 16 years, 26 horses were treated for open fractures involving the splint bones. Treatment consisted of surgical excision of fracture fragments and sequestra, and curettage of infected and unhealthy tissues. The splint bone distal to the fracture was removed in nine horses in which the attachment of the splint bone to the cannon bone via the interosseous ligament did not provide adequate stability. In two horses it was considered necessary to stabilise the proximal fragment by internal fixation and infection developed in both of them; one of these horses was destroyed on humane...
Sedgwick AD, Dawson J, Lees P.Subpopulations of equine leucocytes, polymorphonuclear and mononuclear cells, were separated from whole blood on a discontinuous Percoll gradient and used in studies of chemokinesis and chemotaxis. Polymorphonuclear cells responded to the chemo-attractant properties of zymosan-activated plasma in Boyden chamber and agarose microdroplet assays but they responded only slightly (Boyden chamber) or not at all (agarose microdroplet) to the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). Equine mononuclear cell movement was increased by FMLP in both assay systems and these cells also respond...
Mira J, Herman M, Zakia LS, Olivo G, Araujo JP, Borges AS, Oliveira-Filho JP.Aural plaques can be found on the inner surfaces of one or both ears of horses. Despite their low malignancy, these lesions can sometimes cause discomfort and sensitivity in horses, and a loss in commercial value due to their aesthetic effect. There has been a study describing the epidemiological features and the clinical prevalence of equine aural plaques in Brazil. Objective: To determine the clinical prevalence and selected associated factors of aural plaques. Methods: In the study, 891 horses were assessed for aural plaques. The sample group had a median age of 5 years and comprised both s...
Straticò P, Suriano R, Sciarrini C, Varasano V, Petrizzi L.To report laparoscopic-assisted cystotomy and inguinal cystostomy for treating bladder urolithiasis in a gelding. Methods: Clinical report. Methods: Twelve-year-old Appaloosa gelding. Methods: A laparoscopic approach was used to locate and grasp the bladder, which was exteriorized through an enlarged instrument portal for cystotomy to remove the calculus. During withdrawal, the calculus fragmented into multiple pieces. To avoid urethral occlusion and facilitate elimination of these fragments, an inguinal cystostomy was created. The seromuscular layer of the bladder was circumferentially secure...
Santos AC, Nogueira CEW, Dos Santos Suñe Moraes B, Müller V, Mousquer MA, Leite FPL.Equine theileriosis, caused by the Theileria equi protozoan, is a disease of worldwide importance. T. equi expresses surface proteins, of which the EMA-2 protein is a promising antigen for vaccine use. The aim of this study was to evaluate the immune response of adult horses, pregnant mares, and foals to an experimental EMA-2 protein of recombinant T. equi vaccine. A total of 46 horses were used in this study for vaccine trials and challenges. Twelve geldings, 14 pregnant mares, and 14 foals were divided into vaccinated and control groups. Total serum specific anti-rEMA-2 IgG, IgG subclasses, ...
Xue C, Cavanaugh SM.Reports of ante-mortem diagnosis of cardiovascular diseases in donkeys (Equus asinus) are rare. This case report describes the echocardiographic findings of suspected mitral valve dysplasia in a 3-year-old Nevisian donkey jenny presented for evaluation of a grade III/VI left-sided systolic murmur. Pertinent findings on transthoracic echocardiography included double mitral regurgitant jets and a bridge of tissue between the septal and mural mitral leaflets. Based upon the mild degree of cardiac remodeling and absence of clinical signs, therapeutic intervention was deemed unnecessary, and the je...
Velie BD, Hamilton NA, Wade CM.Many attempts have been made to improve the well-being of racing Thoroughbreds through improvements in management and veterinary care. However, these attempts are often limited by the industry's ability to regulate a large number of environmental variables and as a result have arguably had limited success in providing long-lasting change for the breed. Objective: To identify heritable durability traits for Thoroughbred horses racing in Australia and Hong Kong. Methods: Heritability analysis of a longitudinal dataset. Methods: Performance data on the Thoroughbred populations racing in Australia...
Berryhill EH, Urbina NS, Marton S, Vernau W, Alonso FH.The Wellness Ready Test (WRT) is a lateral flow, stall-side assay that measures equine insulin in whole blood and requires validation before recommending clinical use. We evaluated intra- and inter-assay precision and linearity and compared the WRT with a radioimmunoassay (RIA). Tested concentrations ranged from 695 pmol/L (100 μIU/mL). For 20 replicates at each insulin level, intra-assay CVs of the WRT for insulin were 13.3%, 12.9%, and 15.3% at low (139-278 pmol/L; 20-40 μIU/mL), intermediate (278-417 pmol/L; 40-60 μIU/mL), and high (>417 >60 μIU/mL) concentrations...
Rantanen NW.Ultrasound examination offers important diagnostic and prognostic information in renal disease of the horse. Differentiation between acute nephrosis and chronic renal disease can usually be made because of the advanced degree of morphologic change usually prevalent in chronic conditions. Dilatations of the recesses and pelvis (hydronephrosis) as well as the relative thickness of the renal cortex and medulla are readily determined. Mineral densities (calculi) are recognizable by their characteristic acoustic shadowing.
Baerg SD, Russell DA, LeVan LM, Kirker-Head CA.A 22-year-old thoroughbred gelding was presented for evaluation and treatment of chronic dental disease. The horse had a history of quidding and abnormal bite behavior. Intraoral examination revealed signs of chronic generalized gingival inflammation and severe dental caries affecting the maxillary and mandibular incisor teeth. Treatment was provided on two separate visits over an interval of four months. The first visit consisted of the surgical extraction of three unrestorable incisor teeth and restoration of six carious maxillary incisor teeth. The second visit consisted of conventional end...
Doherr MG, Carpenter TE, Wilson WD, Gardner IA.To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. Methods: 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. Methods: Admission date and geographic location were determined. Scan, Cuzick & Edwards', and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. Results: For all windows > or = 3 days (134 case...
Kilmer DM, Sharp DC, Berglund LA, Grubaugh W, McDowell KJ, Peck LS.Melatonin concentrations in intact (N = 3) and sham-operated (N = 3) mares during March were greater (P less than 0 . 05) during the night than during the day, but this pattern was not seen in 3 mares from which the superior cervical ganglia had been removed bilaterally. When 4 Pony mares were exposed to a photoperiod of 10L:14D for 3 weeks and then to continuous darkness (0L:24D) for another 3 weeks, melatonin levels were greater (P less than 0 . 05) at the end of the 0L:24D period than during the earlier period and still displayed rhythmic fluctuations but were no longer co-ordinated with eq...
Stewart DR, Addiego LA, Pascoe DR, Haluska GJ, Pashen R.Equine relaxin has been previously determined in a small number of pregnant Thoroughbred mares. To better define the normal pregnancy pattern of relaxin, the current study reports on a much larger number of mares. It also was designed to determine if all equids have the same gestational pattern of relaxin secretion. Plasma samples were collected weekly in 24 Standardbred mares, every 7-10 days in 10 pony mares, and daily in late pregnancy from 16 burros. Standardbreds had higher concentrations of relaxin than that reported for Thoroughbreds during most of gestation and did not exhibit the midp...
Verde CR, Simpson MI, Frigoli A, Landoni MF.Pharmacokinetic parameters were established for enantiomers of the nonsteroidal anti-inflammatory drug (NSAID) ketoprofen (KTP) administered as the racemic mixture at a dose of 2.2 mg/kg and as separate enantiomers, each at a dose of 1.1 mg/kg to a group of six horses (five mares and one gelding). A four-period cross-over study in a LPS-induced model of acute synovitis was used. After administration of the racemic mixture S(+)KTP was the predominant enantiomer in plasma as well as in synovial fluid. Unidirectional inversion of R(-) to S(+)KTP was demonstrated but the inversion was less marked ...