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.
Hänni K, Hesford F, Lazary S, Gerber H.Genomic DNA isolated from 20 horses was digested with up to six restriction endonucleases and subjected to southern blot hybridization analysis using various human class II alpha- and beta-chain cDNA probes. A high degree of restriction fragment length polymorphism (RFLP) was found for the DQ alpha, DP beta, DQ beta and DR beta probes, about 20 polymorphic bands being detected for each. DR alpha showed 2-4 polymorphic bands, whereas no evidence for DP alpha-like genes was found. A number of correlations of RFLPs with individual alloantisera were apparent.
Potempa J, Korzus E, Silberring J, Dubin A.1. Noncatalytic protein component (NPC), a strongly acidic protein (pH = 4.5) was separated from native horse leucocyte elastase 1. 2. This protein reduces elastinolytic properties of elastases: 1 and 2A probably by decreasing their isoelectric points. 3. A possible regulatory role of this protein may be inferred from a higher affinity of elastase 1 to NPC rather than to elastin.
Kopp E, Mayr B, Schleger W.The expression of nucleolus organizer region (NOR) activity in diploid cells was investigated in a model mammalian hybrid system, the hinny (female ass x male horse), by sequential Ag-NOR and chromomycin A3/distamycin A/DAPI (CDD) staining ion lectin-stimulated peripheral blood lymphocytes. In the majority of cases we found non-expression of the horse-derived NOR chromosomes in the hinny. However, in one case there was strong NOR expression on horse-derived chromosome no. 1.
Cross DT, Ginther OJ.Uterine contractions in 8 nonpregnant and 13 pregnant mares were studied using ultrasonography. A 1-min video tape recording was made of longitudinal real-time images of the uterine body. An overall uterine contractile activity score (0 = no or minimal activity to 4 = maximal activity) was assigned to each video tape segment. There was a day effect (P less than .01) and an interaction (P less than .01) of reproductive status X day. Uterine activity scores were highest on d 14 to d 18 (d 0 = day of ovulation) for nonpregnant mares and on d 10 to d 14 for pregnant mares. Uterine activity scores ...
Evans DL, Rose RJ.Six Standardbred horses were used to evaluate the time course of pulmonary gas exchange, ventilation, heart rate (HR) and acid base balance during different intensities of constant-load treadmill exercise. Horses were exercised at approximately 50%, 75% and 100% maximum oxygen uptake (VO2 max) for 5 min and measurements taken every 30 s throughout exercise. At all work rates, the minute ventilation, respiratory frequency and tidal volume reached steady state values by 60 s of exercise. At 100% VO2 max, the oxygen consumption (VO2) increased to mean values of approximately 130 ml/kg.min, which ...
Browning GF, Ficorilli N, Studdert MJ.Two previously unknown and distinct herpesviruses were isolated from donkeys. One, with the characteristics of a betaherpesvirus, was isolated from the leukocytes of an apparently healthy donkey, while the second, an alphaherpesvirus, was recovered from the nasal cavity of donkeys given high doses of corticosteroids, and caused rhinitis in two seronegative weanling donkeys when they were intranasally infected. Few, if any, restriction endonuclease fragments were shared by the donkey betaherpesvirus, equine herpesvirus 2 (EHV 2) or EHV 5, a second distinctly different equine betaherpesvirus, no...
Katila T.Altogether 156 equine endometrial biopsies were carried out during the post partum (p.p.) period: immediately after parturition until 15 days after foaling. The histological changes are described. The rapid restoration of the equine endometrium is remarkable. The destruction of the luminal epithelium is minor and regeneration takes place rapidly. Remnants of the placenta, the microcotyledons and desquamated cells, have disappeared by 5 p.p. The transformation of glands from a pronounced secretory pattern to normal appearance also takes only 5 days. The occurrence of neutrophils and lymphocytes...
Mermod L, Hoppeler H, Kayar SR, Straub R, Weibel ER.Muscle samples were taken from the superficial part of the semitendinosus muscle of four standardbred horses to compare the effects of three different fixation procedures on fiber size and capillarity. Infiltration fixation in an extended position of the muscle was compared to immersion fixation and infiltration fixation in a flexed position of the limb. The capillary length density was used to estimate muscle capillarity. Infiltration fixation was found to be a viable alternative to perfusion fixation of muscles for morphometry of fiber size and capillary length density allowing muscle tissue...
Cribb PH.Forty-five horses were maintained on halothane or isoflurane anesthesia for at least 90 minutes and received positive pressure ventilation after the first 30 minutes of anesthesia. Parameters monitored included end-tidal partial pressure of carbon dioxide (ETPCO2), arterial blood pressure, and arterial blood gases and pH. There was a statistically significant correlation between end-tidal carbon dioxide and arterial partial pressure of carbon dioxide (PaCO2) for both halothane and isoflurane anesthesia. There was no significant correlation between end-tidal carbon dioxide and either body weigh...
Schorr G.Serum iron concentration and iron-binding capacity were determined in 34 respectively 35 clinically healthy horses of different sex, with the age of 3 to 21 years. In the Warm blooded horse, the Half bred, the Haflinger horse, the Heavy horse and the Arabian Haflinger the mean serum iron concentration amounted to 253 +/- 66 micrograms/dl, 202 +/- 87 micrograms/dl, 166 +/- 67 micrograms/dl, 183 micrograms/dl and 366 micrograms/dl, while the iron-binding capacity in the Warm blooded horse, the Half bred, the Haflinger horse, the Thoroughbred, the Heavy horse and the Arabian Haflinger ran up to 4...
Martínez R, Godoy A, Naretto E, White A.1. Packed cell volume (PCV) and plasma catecholamines, cortisol and glucose were determined in blood samples obtained from race horses, after competition. 2. All these parameters were higher than basals but catecholamines increased 6-7 times while cortisol was enhanced only by 25%. 3. The increase of glucose and PCV was related to the rise of catecholamines. 4. In samples withdrawn after overnight stress caused by change of horseshoes, it was not possible to find values from basal values significantly different. 5. Influence of nervous temperament was observed only in the higher hematocrit fou...
Bermudez V, Miller RB, Johnson W, Rosendal S, Ruhnke L.The growth of Mycoplasma equigenitalium and Mycoplasma subdolum from specimens collected from the clitoral fossa of each of four Standardbred mares was not diminished by freezing of the specimens in liquid nitrogen (-196 degrees C) for up to 30 days when compared to samples cultured immediately.
Kersjes AW, Bras GE, Németh F, van der Velden MA, Firth EC.This retrospective study presents the results of surgical treatment of obstructive colic in horses operated in the last decade (1976-1985). The overall short-term recovery rate (i.e. discharged from hospital) was 51% of cases presented for surgery, and 68% of cases which were considered to be amenable to surgical therapy. For long-term results (6 months-8 years follow up) these percentages must be reduced by about 15% due to mortality after discharge. Special attention has been given to surgery of the ileum, which is often involved in strangulation or obturation, and accounts for about 26% of ...
Erickson HH, Sexton WL, Erickson BK, Coffman JR.The recognition of the horse as a natural athlete has led to increased interest in equine sports medicine, exercise physiology, new training methods, and factors improving the performance of horses (Engelhardt, 1977; Milne et al., 1977; Bayly et al., 1983b; Persson et al., 1983). A considerable amount of research has been performed in recent years in order to describe the physiological responses of the horse to exercise and training (for reviews see Engelhardt, 1977; Physick-Sheard, 1985; Rose, 1985). Most of these studies, however, have examined the effects of acute exercise training rather t...
Angelos J, Oppenheim Y, Rebhun W, Mohammed H, Antczak DF.The relationship between breed and the risk of developing sarcoid tumours or uveitis of unknown etiology was evaluated in a retrospective study of 16242 equine cases admitted between 1975 and 1987 to the New York State College of Veterinary Medicine Large Animal Hospital, and 3198 equine tissue samples sent to the New York State Veterinary Diagnostic Laboratory between 1977 and 1987. Of 120 sarcoid cases from the Large Animal Hospital, sarcoids were twice as likely to develop in Quarter Horses (odds ratio, OR = 1.8, P less than 0.05) relative to Thoroughbreds and less than half as likely to de...
Bostedt H.A clinical study about the effects of a beta 2-mimetic agent (Clenbuterol) in mares with pregnancy disorders or disorders during the periparturient period (n = 34) is reported. In general, a single dose of 0.3 mg Clenbuterol given i.v. induces sufficient tocolysis. Subsequent doses or follow-up treatment depend upon individual development during dystocia, indication of treatment and clinical preparturient status (dorsoflexio uteri ante partum, abortus imminens, preparturient labor pains).
Cabañes FJ, Abarca L, Bragulat MR, Bruguera T.A phaeohyphomycotic infection caused by Alternaria alternata is reported in a 5-month-old Spanish mare. The diagnosis was made by direct microscopic examination and by repeated isolation of the fungus in culture. This is the first documented case to be reported in Spain.
Fritsch R, Hausmann R.In 26 horses measurings of blood pressure, using the Dinamap 1255 research monitor, were performed and compared for accuracy with blood pressure values obtained by direct measurement in the arteria carotis. It was found that oscillometrically ascertained initial blood values in standing horses have a sufficient correlation to initial blood pressure values obtained by direct measurement. But every blood pressure change is registered too late, when using the oscillometric blood pressure apparatus. This temporal delay becomes unacceptable, when a considerable increase in blood pressure occurs. A ...
Hinrichs K, Sertich PL, Solorzano NM, Caldwell LA.An immediate, qualitative enzyme-linked immunosorbent assay (ELISA) for progesterone was evaluated for use in determining the day of ovulation in an equine embryo transfer program. Plasma samples were collected from 27 mares from the third day of estrus to the second day of diestrus for 50 cycles. Ovulation was detected by ultrasound examination per rectum. Plasma progesterone concentrations were estimated using the qualitative assay to detect the time of the rise in progesterone after ovulation. Qualitative scores were compared to progesterone concentrations for the same samples as measured b...
Doran R, Allen D, Gordon B.Ovarian granulosa theca cell tumours were removed surgically in 10 mares. Stapling instruments were used to facilitate haemostasis of the ovarian pedicle in five out of 10 cases and as a sole method of haemostasis in the remaining five cases. Postoperative haemorrhage from the ovarian pedicle was suspected in only one case. All cases survived long term follow-up from six months to four years. Results from this series of cases indicate that stapling instruments provide a rapid, easy and efficient means of ligating ovarian pedicles when performing ovariectomy in the mare.
Landgren GL, Gillespie JR, Fedde MR, Jones BW, Pieschl RL, Wagner PD.We studied mechanisms of O2 transport in 6 adult (2-5 year old) horses at rest and during steady-state exercise on a treadmill (0% slope) at 12 m/s (a submaximal gallop). Oxygen consumption was measured using an open-flow system. Arterial and mixed venous blood samples were simultaneously obtained for measurement of O2 content and hemoglobin concentration. VO2 increased from 1.5 +/- 0.2 L/min at rest to 46.2 +/- 4.8 L/min during exercise. HR increased from a resting value of 36.9 +/- 2.5 bpm to 196.5 +/- 10.9 bpm and the arterio-venous O2 content difference (a-v O2) increased from 4.2 +/- 0.8 ...
Cohen D, Bosler EM, Bernard W, Meirs D, Eisner R, Schulze TL.A serologic survey of horses in the New Jersey-Pennsylvania area demonstrated that about 10% (6.2-14.2%) have significant levels of serum antibody to Borrelia burgdorferi. However, in a highly endemic area of central New Jersey, up to 60% of the mares and yearlings samples on one farm were seropositive. In 1983, sera from this same farm exhibited only 12% positives in mares and 35% positives in yearlings. Longitudinal studies of paired sera obtained from individual yearlings over a 6-month period in 1985 showed that 34% of them declined during the period. A new clinical syndrome associated wit...
Toutain PL, Oukessou M, Autefage A, Alvinerie M.Using a specific high-performance liquid chromatographic technique, plasma hydrocortisone values were measured hourly in 6 horses and every 10 minutes in 4 horses over 24 hours. Both circadian and episodic variation was observed. The mean plasma hydrocortisone concentration was a maximum of 58.8 +/- 9.54 ng/ml at 9.19 +/- 0.59 hr and a minimum of 27.85 +/- 6.85 g/ml at 21.19 +/- 0.59 hr. The number of episodes of secretion was 10.0 +/- 1.41; the mean amplitude and duration of peak were 26.21 +/- 3.71 ng/ml and 105.25 +/- 21.24 min respectively.
Pause B, Nolte I, Geiss V, Mayer H, Lasch HG.A thoroughbred horse, suffering from intermittent lameness was treated with streptokinase, urokinase and warfarin. The appearing fibrinolytic changes in coagulation were exhibited in a resonance thrombogram. In attendant coagulation studies fibrinogen- and fibrin-degradation products were demonstrated. The stallion does not show any lameness since the end of the treatment and is standing in a breeding station since March 1988.
Ralston SL.A survey was taken of dietary management and training schedules of 54 horses competing in two 160 km endurance races. A total of 52 owners, representing 54 horses, responded to a questionnaire distributed prior to the races. Diet and training schedules were compared between horses that successfully completed the races and those that were eliminated for metabolic reasons. Horses that completed the races were 11.5 +/- 4 years old, weighed 429 +/- 4.5 kg and were ridden 61 +/- 32 km a week when training. Feed intake was reported as "free choice hay or pasture" by 34 of the respondents. Dry matter...
Cochaux P, Van Sande J, Swillens S, Dumont JE.The characteristics of the iodide-induced inhibition of cyclic AMP accumulation in dog thyroid slices have been previously described [Van Sande, J., Cochaux, P. and Dumont, J. E. (1985) Mol. Cell. Endocrinol. 40, 181-192]. In the present study we investigated the characteristics of the iodide-induced inhibition of adenylate cyclase activity in dog and horse thyroid. The inhibition of cyclic AMP accumulation by iodide in stimulated horse thyroid slices was similar to that observed in dog thyroid slices. The inhibition was observed in slices stimulated by thyroid-stimulating hormone, cholera tox...
Jaussaud P, Courtot D, Guyot JL, Paris J.The main metabolite of flunixin, a hydroxylated product, has been identified by gas chromatography-mass spectrometry and 1H NMR spectroscopy in equine urine and plasma. The method also permits the qualitative monitoring of the urinary elimination of the drug and its metabolite. The two products are detected up to 175 and 54 h, respectively, after a single intravenous administration at the dose of 1 mg/kg. Simultaneous detection of the two compounds increases the reliability of anti-doping control analysis.
Summers PM, Wells KE, Adkins KF.The features of an ossifying ameloblastoma in a 5-year-old gelding are described. The tumour developed in the angle of the right mandible and microscopically consisted of multiple follicles and islands of epithelial tissue adjacent to which were trabeculae of bone, osteoid and compact collagenous tissue.
Splitter GA, Incefy G, Iwata T, McGuire TC.Arabian horses with severe combined immunodeficiency disease (SCID) were evaluated for thymic hormone activities using thymic extracts and sera. Extracts prepared from thymus of SCID horses were able to increase the number of spleen cells responding to sheep red blood cells in irradiated, bone marrow-reconstituted mice. In addition, ultrafiltrates prepared from sera of these immunodeficient horses, which contained material with molecular weight of less than 50,000 Daltons could (a) induce a population of human bone marrow precursor cells to differentiate into cells bearing SRBC receptors and f...
Ketzner KM, Stewart AA, Byron CR, Stewart M, Gaughan EM, Vanharreveld PD, Lillich JD.Describe the use of a phalangeal cast as treatment for wounds in the pastern and foot region of horses. Secondly, to evaluate the healing and soundness of horses treated with phalangeal casts. Methods: Retrospective study of 49 horses. Procedures Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained. Results: Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At...
Delbeke FT, Landuyt J, Debackere M.Concentrations of the non-steroidal anti-inflammatory drug (NSAID) alclofenac were determined by a sensitive high performance liquid chromatographic procedure in plasma and urine of horses following oral administration of a dose of 3 g. In plasma, alclofenac was present in detectable concentrations for 72 h. The plasma disposition in individual horses was best described by a bi-compartmental model with two successive rate constants ka1 = 0.05 +/- 0.06 h-1 and ka2 = 0.06 +/- 0.01 h-1. Alclofenac half-lives t1/2 alpha and t1/2 beta were 1.0 +/- 0.8 h and 6.9 +/- 1.5 h, respectively. Maximal conc...
Tschudi P.The cardiac arrhythmias, classified in disturbances of impulse formation and conduction disturbances, their genesis and clinical significance are described and illustrated with electrocardiograms, registered with the bipolar chest leads.
Dos Santos GC, Di Filippo PA, da Fonseca LA, Quirino CR.The purpose of this study was to compare the extent of inflammation response in the middle carpal joints of healthy horses following intra-articular injection of 2% lidocaine, 0.5% bupivacaine, or 0.9% saline solution. The right middle carpal joint of 20 horses was injected with 5 mL of 0.5% bupivacaine (GB, n = 10) or 5 mL of 2% lidocaine (GL, n = 10). The left middle carpal joint of horses was used as a control (5 mL 0.9% saline). Serum and synovial fluid (SF) were aseptically collected before and at predetermined times after each injection. Serum and synovial fluid protein, albumin, tra...
Jones SA, Whitcomb MB, Vaughan B, Goorchenko G, Busch R, Kilcoyne I, Spriet M.Femoral fractures are often catastrophic in large animals. Radiographic diagnosis is limited by patient size and feasibility, especially in ambulatory settings. Ultrasonography is widely available and may provide an alternative to radiography for definitive diagnosis. 12 large animals (6 horses, 5 cattle, and 1 elephant). Retrospective analysis of large animal patients diagnosed with femoral fracture by use of femoropelvic ultrasonography (2000 to 2019). 5 of 12 cases were ≤ 1 year of age. The remaining 7 cases were 2 to 33 years of age (median, 13 years). All patients developed severe acute...
Slota E, Wnuk M, Bugno M, Pienkowska-Schelling A, Schelling C, Bratus A, Kotylak Z.Cytogenetic investigations of the nucleolar-organizing regions (NORs) show that there is variation in the transcriptional activity of rDNA in many organisms. As a consequence, genetic polymorphism of these regions has been detected. The aim of the present study was to evaluate the hypothetic genetic mechanisms determining the NORs polymorphism of the domestic horse chromosomes. Molecular cytogenetic analyses were carried out on Hucul horses and the following techniques were used: fluorescence in situ hybridization (FISH), telomere primed in situ synthesis (PRINS), in situ nick-translation with...
Perkins G, Ainsworth DM, Erb HN, Del Piero F, Miller M, Wilkins PA, Palmer J, Frazer M.A retrospective multicentre study comparing historical, clinical, haematological, acid-base and biochemical findings of foals with Equine herpesvirus-1 (EHV-1) infection, septicaemia or prematurity was performed to determine if early diagnosis of EHV-1 foals was possible. Fifty-three foals were studied and were assigned to one of 2 groups: herpes positive (n = 14) or herpes negative (n = 39). The latter group included 20 septic, 11 premature, and 8 premature and septic foals. The presence of herpes antigen was confirmed by immunoperoxidase histochemical staining of tissues from necropsied foal...
Brownlow MA, Hutchins DR, Johnston KG.Cells in the peritoneal fluid from 159 horses were examined in Giemsa stained preparations using light microscopy. Normal mesothelial cells showed an oval nucleus with finely reticular chromatin and pale blue cytoplasm. Activated mesothelial cells occurred in fluids derived from mesothelium under acute or subacute, non-septic stimulus and were remarkable for their pleomorphism and intense basophilia which may mimic neoplasia. Transformed mesothelial cells seen in chronic inflammatory fluids were sometimes phagocytic and showed conspicuous cytoplasmic vacuolation.
Schumacher J, Kemper DL, Helman RG, Edwards JL.The incisive bones (premaxillae) and rostral portions of the maxillae of a horse were infected with dermatiaceous fungi causing phaeohyphomycosis. The pre-maxillae were exposed by creating and reflecting labial and palatal mucoperiosteal flaps, and obstetrical wire was used to remove the affected bones. Labial and palatal flaps were apposed in 2 layers, using absorbable sutures. The sutured wound healed without complication. The horse was able to prehend hay and long grass without difficulty, and the owner considered the horse's facial appearance to be nearly normal. This technique may be usef...
Kai K, Tateyama S, Miyoshi N, Yamaguchi R, Uchida K, Rostami M.Genomic DNAs of cattle, horses, pigs, dogs, cats and chickens were surveyed using Southern blot hybridization analysis, with a human EGFR cDNA fragment. Several bands with different numbers and molecular weights were observed under the condition of low stringency in the individual animal species. The bands showing DNA polymorphism were observed among bovine genomic PstI-digested DNAs from 4 individuals and EcoRI-digested genomic DNAs from 4 chickens. These results may provide basic data which are useful for analysis of tumorigenetic mechanisms in domestic animals.
Tobin T, Tai HH, Tai CL, Houtz PK, Dai MR, Woods WE, Yang JM, Weckman TJ, Chang SL, Blake JW.We have developed and evaluated a one step enzyme-linked immunosorbent assay (ELISA) test for fentanyl as part of a panel of pre- and post-race tests for narcotic analgesics in racing horses. This ELISA test detects fentanyl with an I-50 of about 100 pg/ml. The test is economical in that it can be read with an inexpensive spectrophotometer, or even by eye. The test is rapid, and ten samples, a normal pre-race complement, can be analyzed in about twenty minutes. The test readily detects the presence of fentanyl or its metabolites in equine blood and urine from two and twenty-four hours respecti...
The Journal of heredityMarch 1, 1988
Volume 79, Issue 2 100-106 doi: 10.1093/oxfordjournals.jhered.a110461
Woolf CM, Swafford JR.The ultrastructural imaging of melanocytes coupled with analyses to detect sulfur-containing melanosomes by energy-dispersive X-ray spectroscopy were used to test the hypothesis that the yellowish-red and black pigments found in Arabian horses result from pheomelanogenesis and eumelanogenesis, respectively. These procedures detected pheomelanosomes in follicles at the base of hairs in chestnut horses and eumelanosomes in follicles at the base of hairs in black horses. By analyzing tissue obtained by skin biopsy, these procedures also demonstrated that skin melanocytes in a chestnut horse produ...
Pellegrini A, Von Fellenberg R.A new and probably unique elastase inhibitor of horse serum was identified, purified to homogeneity and called pre-alpha 2-elastase inhibitor of the horse. Electrophoretically it migrated immediately in front of the alpha 2 position. Its molecular weight was 188 000 by pore limit polyacrylamide gel electrophoresis and 225 000 by Sephadex G-200 gel filtration. The inhibitor was composed of at least two non-identical polypeptide chains of Mr 68 400 and 87 600. A banding pattern of restricted heterogeneity focused between pH 4.9 and 5.2 was revealed by isoelectric focusing. Of 13 animal, microbia...
Staempfli SA, Saied A, Wakamatsu N, Serra V, Eades SC.A 5-day-old Thoroughbred colt was presented with profuse watery diarrhea, hypovolemic shock, and a patent urachus. Despite intensive medical therapy, the colt was euthanized 15 d later due to poor clinical response. Necropsy revealed a small intestinal structural abnormality that formed a closed jejunal ring. Although rare, intestinal malformations should be considered in neonatal foals with clinical signs resembling enteritis. Entérite septique résistante au traitement causée par une malformation jéjunale chez un poulain Thoroughbred âgé de 5 jours. Un poulain Thoroughbred âgé de 5 jo...
Cotrel C, Leleu C, Courouce-Malblanc A.A close relationship between limb and respiratory rhythms has been shown in clinically healthy galloping horses due to mechanical constraints in the thoracic region. This synchronisation leads to a 1/1 ratio between stride frequency (SF) and respiratory frequency (RF) during galloping. Very little is known about locomotor-respiratory coupling (LRC) during fast trot. Objective: To investigate stride and respiratory rates during a standardised exercise test on the track in Standardbred Trotters. Methods: Forty-four French trotters age 2-10 years performed a standardised exercise test consisting ...
Chou CC, Webb AI, Brown MP, Gronwall RR, Vickroy TW.Concentrations of caffeine (CA) and two metabolites were measured simultaneously in venous blood and splenius muscle of adult horses using a semi-automated in vivo microdialysis sampling technique. Dialysates from muscle and jugular vein were collected continuously for 48 h and drug levels were determined by high performance liquid chromatography (HPLC). Following i.v. injection, CA (3 mg/kg) attained a peak blood level of nearly 5400 +/- 600 ng/mL and decreased with a half-life of 15.3 +/- 0.7 h. Pharmacokinetic and statistical comparisons between CA concentrations in jugular dialysates and p...