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Topic:Equine Health

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.
Femoral epiphyseal cartilage matrix changes at predilection sites of equine osteochondrosis: Quantitative MRI, second-harmonic microscopy, and histological findings.
Journal of orthopaedic research : official publication of the Orthopaedic Research Society    February 8, 2016   Volume 34, Issue 10 1743-1752 doi: 10.1002/jor.23176
Martel G, Couture CA, Gilbert G, Bancelin S, Richard H, Moser T, Kiss S, Légaré F, Laverty S.Osteochondrosis is an ischemic chondronecrosis of epiphyseal growth cartilage that results in focal failure of endochondral ossification and osteochondritis dissecans at specific sites in the epiphyses of humans and animals, including horses. The upstream events leading to the focal ischemia remain unknown. The epiphyseal growth cartilage matrix is composed of proteoglycan and collagen macromolecules and encases its vascular tree in canals. The matrix undergoes major dynamic changes in early life that could weaken it biomechanically and predispose it to focal trauma and vascular failure. Subre...
Effects of a long-day light programme on the motility and membrane integrity of cooled-stored and cyropreserved semen in Shetland pony stallions.
Animal reproduction science    February 8, 2016   Volume 167 68-73 doi: 10.1016/j.anireprosci.2016.02.008
Deichsel K, Schrammel N, Aurich J, Aurich C.Increasing day length in spring stimulates reproductive functions in horses. In this study, we have analysed the effect of artificial long days on the quality of cooled-stored and cryopreserved semen in Shetland stallions. Stallions of the treatment group (AL, n = 8) were exposed to 16 h light and 8h darkness from 15th December to 20th March while control stallions (CON, n = 7) were kept under natural photoperiod. Semen was collected once weekly and processed for cooled-storage and cryopreservation once per month. Total and progressive motility and percentage of membrane intact spermatozoa wer...
The use of nutritional supplements in dressage and eventing horses.
Veterinary record open    February 8, 2016   Volume 3, Issue 1 e000154 doi: 10.1136/vetreco-2015-000154
Agar C, Gemmill R, Hollands T, Freeman SL.The aim of the study was to determine which types of nutritional supplements were used in dressage and eventing horses, and the reasons that owners used supplements. An online questionnaire was distributed through British Eventing and Dressage websites, to collect data on demographics of owners and their horses, supplements used and their opinion on health and performance problems. Data were evaluated using descriptive analysis, Sign and Fisher's exact tests for quantitative data, and categorisation of qualitative data. In total, 599 responses met the inclusion criteria (441 dressage and 158 e...
Comparison of alfaxalone, ketamine and thiopental for anaesthetic induction and recovery in Thoroughbred horses premedicated with medetomidine and midazolam.
Equine veterinary journal    February 6, 2016   Volume 49, Issue 1 94-98 doi: 10.1111/evj.12548
Wakuno A, Aoki M, Kushiro A, Mae N, Kodaira K, Maeda T, Yamazaki Y, Ohta M.There is limited information on clinical use of the new injectable anaesthetic agent alfaxalone in Thoroughbred horses. Objective: To compare anaesthetic induction and recovery characteristics and cardiopulmonary responses between alfaxalone, ketamine and thiopental in Thoroughbred horses premedicated with medetomidine and midazolam. Methods: Randomised blinded experimental cross-over study. Methods: Six Thoroughbred horses were anaesthetised 3 times with alfaxalone 1 mg/kg bwt, ketamine 2.5 mg/kg bwt or thiopental 4 mg/kg bwt after premedication with medetomidine 6 μg/kg bwt and midazola...
Environmental heat and airborne pollen concentration are associated with increased asthma severity in horses.
Equine veterinary journal    February 6, 2016   Volume 48, Issue 4 479-484 doi: 10.1111/evj.12559
Bullone M, Murcia RY, Lavoie JP.Clinical exacerbations of severe equine asthma (formerly recurrent airway obstruction [RAO]) are more frequently reported during winter when horses are exposed to airborne dusts during stabling. However, we have also observed a worsening of clinical signs on days during a heatwave. Objective: To investigate the association between environmental temperature and humidity and clinical signs of asthma in horses during clinical exacerbation of the disease. Methods: Retrospective longitudinal study. Methods: Historical data on 14 severe asthmatic horses exposed to a dusty environment and evaluated u...
Cardiovascular, respiratory and metabolic responses to apnea induced by atlanto-occipital intrathecal lidocaine injection in anesthetized horses.
Veterinary anaesthesia and analgesia    February 5, 2016   Volume 43, Issue 6 590-598 doi: 10.1111/vaa.12344
Guedes A, Aleman M, Davis E, Tearney C.To determine physiologic responses to apnea-induced severe hypoxemia in anesthetized horses. Methods: Prospective experimental study. Methods: Six university-owned horses with a median (range) body weight of 500 (220-510) kg and aged 13.5 (0.8-24.0) years scheduled for euthanasia. Methods: Xylazine-midazolam-ketamine-anesthetized horses breathing room air spontaneously were instrumented with a facial artery catheter for pressure measurement and blood sampling, and were made apneic with atlanto-occipital intrathecal lidocaine (4 mg kg ). Cardiopulmonary, biochemical and hematologic variable...
Experiences with a voluntary surveillance system for early detection of equine diseases in Switzerland.
Epidemiology and infection    February 5, 2016   Volume 144, Issue 9 1830-1836 doi: 10.1017/S0950268816000091
Struchen R, Hadorn D, Wohlfender F, Balmer S, Süptitz S, Zinsstag J, Vial F.Clinical observations made by practitioners and reported using web- and mobile-based technologies may benefit disease surveillance by improving the timeliness of outbreak detection. Equinella is a voluntary electronic reporting and information system established for the early detection of infectious equine diseases in Switzerland. Sentinel veterinary practitioners have been able to report cases of non-notifiable diseases and clinical symptoms to an internet-based platform since November 2013. Telephone interviews were carried out during the first year to understand the motivating and constrain...
Qualitative assessment of bone density at the distal articulating surface of the third metacarpal in Thoroughbred racehorses with and without condylar fracture.
Equine veterinary journal    February 5, 2016   Volume 49, Issue 2 172-177 doi: 10.1111/evj.12544
Loughridge AB, Hess AM, Parkin TD, Kawcak CE.Changes in subchondral bone density, induced by the repetitive cyclical loading of exercise, may potentiate fatigue damage and the risk of fracture. Objective: To use computed tomography (CT) to characterise bone density patterns at the articular surface of the third metacarpal bone in racehorses with and without lateral condylar fractures. Methods: Case control METHODS: Computed tomographic images of the distal articulating surface of the third metacarpal bone were obtained from Thoroughbred racehorses subjected to euthanasia in the UK. Third metacarpal bones were divided into 3 groups based ...
Proximal suspensory desmopathy in hindlimbs: A correlative clinical, ultrasonographic, gross post mortem and histological study.
Equine veterinary journal    February 4, 2016   Volume 49, Issue 1 65-72 doi: 10.1111/evj.12563
Dyson S, Murray R, Pinilla MJ.It has been suggested that ultrasonography is unreliable for the detection of hindlimb proximal suspensory desmopathy (PSD) based on comparisons between ultrasonographic and magnetic resonance images. Objective: To compare ultrasonography with gross and histopathological post mortem examination in horses with PSD diagnosed based on ultrasonography and control horses. Methods: Retrospective descriptive study. Methods: Part 1: 19 horses with hindlimb PSD and 10 control horses were humanely destroyed. Twenty control limbs and 37 lame limbs were examined grossly and 40 suspensory ligaments (SLs) w...
Positive selection in the SLC11A1 gene in the family Equidae.
Immunogenetics    February 4, 2016   Volume 68, Issue 5 353-364 doi: 10.1007/s00251-016-0905-2
Bayerova Z, Janova E, Matiasovic J, Orlando L, Horin P.Immunity-related genes are a suitable model for studying effects of selection at the genomic level. Some of them are highly conserved due to functional constraints and purifying selection, while others are variable and change quickly to cope with the variation of pathogens. The SLC11A1 gene encodes a transporter protein mediating antimicrobial activity of macrophages. Little is known about the patterns of selection shaping this gene during evolution. Although it is a typical evolutionarily conserved gene, functionally important polymorphisms associated with various diseases were identified in ...
Management of the pregnant mare and long-term consequences on the offspring.
Theriogenology    February 4, 2016   Volume 86, Issue 1 99-109 doi: 10.1016/j.theriogenology.2016.01.028
Peugnet P, Robles M, Wimel L, Tarrade A, Chavatte-Palmer P.The study of early developmental conditioning of health and disease in adulthood is particularly relevant in the horse, which is bred mainly to perform in demanding sport challenges. On the basis of this concept, the management of the broodmare could be considered an effective means to produce animals with the desired features. Knowledge on the Developmental Origins of Health and Disease in the equine species remains relatively scarce, with some experimental studies and one single epidemiologic study. Data highlight the determinant role of the maternal environment for postnatal body conformati...
Effects of erythropoietin on systemic hematocrit and oxygen transport in the splenectomized horse.
Respiratory physiology & neurobiology    February 4, 2016   Volume 225 38-47 doi: 10.1016/j.resp.2016.02.001
McKeever KH, McNally BA, Hinchcliff KW, Lehnhard RA, Poole DC.To test the hypotheses that erythropoietin (rhuEPO) treatment increases systemic hematocrit, maximal O2 uptake (VO2max, by elevated perfusive and diffusive O2 conductances) and performance five female horses (4-13 years) received 15 IU/kg rhuEPO (erythropoietin) three times per week for three weeks. These horses had been splenectomized over 1 year previously to avoid confounding effects from the mobilization of splenic red blood cell reserves. Each horse performed three maximal exercise tests (one per month) on an inclined (4°) treadmill to the limit of tolerance; two control trials and one f...
Risk factors for surgical site infection following laparotomy: Effect of season and perioperative variables and reporting of bacterial isolates in 287 horses.
Equine veterinary journal    February 4, 2016   Volume 49, Issue 1 39-44 doi: 10.1111/evj.12564
Isgren CM, Salem SE, Archer DC, Worsman FC, Townsend NB.Surgical site infection (SSI) is an important cause of post operative morbidity following laparotomy. Objective: To investigate risk factors for SSI, including effect of season and surgery performed outside normal working hours, and to report bacterial isolates and antimicrobial resistance patterns. Methods: Retrospective cohort study. Methods: Data were obtained from horses that had undergone exploratory laparotomy over a 3-year period (2010-2013) in a UK hospital population. SSI was defined as any purulent or serous discharge from the laparotomy incision of >24 h duration that developed d...
Anatomical heterogeneity of tendon: Fascicular and interfascicular tendon compartments have distinct proteomic composition.
Scientific reports    February 4, 2016   Volume 6 20455 doi: 10.1038/srep20455
Thorpe CT, Peffers MJ, Simpson D, Halliwell E, Screen HR, Clegg PD.Tendon is a simple aligned fibre composite, consisting of collagen-rich fascicles surrounded by a softer interfascicular matrix (IFM). The composition and interactions between these material phases are fundamental in ensuring tissue mechanics meet functional requirements. However the IFM is poorly defined, therefore tendon structure-function relationships are incompletely understood. We hypothesised that the IFM has a more complex proteome, with faster turnover than the fascicular matrix (FM). Using laser-capture microdissection and mass spectrometry, we demonstrate that the IFM contains more ...
Genetic Evolution during the development of an attenuated EIAV vaccine.
Retrovirology    February 3, 2016   Volume 13 9 doi: 10.1186/s12977-016-0240-6
Wang XF, Lin YZ, Li Q, Liu Q, Zhao WW, Du C, Chen J, Wang X, Zhou JH.The equine infectious anemia virus (EIAV) vaccine is the only attenuated lentiviral vaccine applied on a large scale that has been shown to be effective in controlling the prevalence of EIA in China. This vaccine was developed by successive passaging of a field-isolated virulent strain in different hosts and cultivated cells. To explore the molecular basis for the phenotype alteration of this vaccine strain, we systematically analyzed its genomic evolution during vaccine development. Results: Sequence analysis revealed that the genetic distance between the wild-type strain and six representati...
A study of the distribution of color Doppler flows in the superficial digital flexor tendon of young Thoroughbreds during their training periods.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 99-104 doi: 10.1294/jes.26.99
Hatazoe T, Endo Y, Iwamoto Y, Korosue K, Kuroda T, Inoue S, Murata D, Hobo S, Misumi K.Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated...
Determination of amino acid profile of mare milk produced in the highlands of the Kyrgyz Republic during the milking season.
Journal of dairy science    February 3, 2016   Volume 99, Issue 4 2480-2487 doi: 10.3168/jds.2015-9717
Mazhitova AT, Kulmyrzaev AA.This study was carried out to determine the influence of milking season on amino acid (AA) profile and chemical composition of milk samples from Kyrgyz native breed mares under traditional pasture conditions. Milk samples were collected monthly from May to August 2014 from mares grazing at 2,200 m above sea level. The AA composition was determined by precolumn derivatization with diethyl ethoxymethylenemalonate in HPLC and 18 AA were determined in mare milk. The analytical parameters of linearity (0.01-4 μg/mL), precision of the method (0.26-4.88% relative standard deviation), derivatization ...
Comparison of an alcohol-based hand rub and water-based chlorhexidine gluconate scrub technique for hand antisepsis prior to elective surgery in horses.
The Canadian veterinary journal = La revue veterinaire canadienne    February 3, 2016   Volume 57, Issue 2 164-168 
da Silveira EA, Bubeck KA, Batista ER, Piat P, Laverty S, Beauchamp G, Archambault M, Elce Y.This prospective clinical study evaluates the effectiveness of an alcohol-based hand rub (Avagard™) for pre-surgical hand antisepsis in an equine hospital and compares it with traditional scrubbing technique using 4% chlorhexidine gluconate sponges and water. Prior to elective surgery, 3 board-certified surgeons were randomly assigned to hand antisepsis with either technique. Culture samples of each hand were taken at 4 times: before and after neutral soap hand wash, after scrub or rubbing technique, and after surgery. There was no significant difference in mean bacterial colony forming unit...
Circadian rhythm of calciotropic hormones, serum calcium, phosphorus and magnesium during the shortest and longest days of the year in horses in New Zealand.
Journal of animal physiology and animal nutrition    February 3, 2016   Volume 100, Issue 6 1058-1066 doi: 10.1111/jpn.12477
Azarpeykan S, Dittmer KE, Gee EK, Marshall JC, Elder P, Acke E, Thompson KG.A study was conducted to determine the circadian rhythms and trends of vitamin D metabolites including 25-hydroxyvitamin D3 , 25-hydroxyvitamin D2 , 1,25-dihydroxyvitamin D and parathyroid hormone, in addition to serum calcium, phosphorus and magnesium concentrations in horses over 48 h on the shortest and longest days of the year in 2013. Five healthy adult horses (Equus caballus) were on a constant pasture feeding regimen, and blood samples were collected from each horse every 3 h over a 48-h period, starting at 07:00 PM on day one and finishing at 07:00 PM on day three, for the measurem...
Pituitary pars intermedia dysfunction (equine Cushing’s disease) in a Thoroughbred stallion: a single report.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 125-128 doi: 10.1294/jes.26.125
Hatazoe T, Kawaguchi H, Hobo S, Misumi K.Equine pituitary pars intermedia dysfunction (PPID) generally occurs in older horses showing hirsutism, delayed molting, weight loss, polydipsia, polyuria, laminitis, and reproductive disorders (in broodmares), but there have been no reports on stallions. This report presents a case of a 21-year-old Thoroughbred stallion that developed hirsutism and experienced delayed molting. There were no abnormal findings for semen quality or the stallion's sexual desire. The horse was diagnosed with PPID based on dexamethasone suppression test and plasma levels of adrenocorticotropic hormone. It was then ...
Modified penetrating keratoplasty with Acell® bioscaffold implant in seven horses with deep full-thickness corneal stromal abscess.
Veterinary ophthalmology    February 3, 2016   Volume 20, Issue 1 46-52 doi: 10.1111/vop.12349
Cichocki BM, Myrna KE, Moore PA.To describe and evaluate a modified penetrating keratoplasty technique utilizing ACell® for management of equine deep stromal or full-thickness corneal stromal abscesses (SA). Methods: Cases presenting to the University of Georgia Ophthalmology service for surgical management of SA necessitating penetrating keratoplasty (PK) were included in the study population. Surgery entailed the use of an ACell® disk sutured within the deep level of a stepped full-thickness corneal incision with an overlying conjunctival pedicle flap placed in the superficial step incision. Patients were evaluated for s...
Different effects of an extended photoperiod treatment on growth, gonadal function, and condition of hair coats in Thoroughbred yearlings reared under different climate conditions.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 113-124 doi: 10.1294/jes.26.113
Suzuki T, Mizukami H, Nambo Y, Ishimaru M, Miyata K, Akiyama K, Korosue K, Naito H, Nagaoka K, Watanabe G, Taya K.One- to two-year-old Thoroughbred colts and fillies being reared in Miyazaki (warm climate) and Hidaka (cold climate), Japan, were administered extended photoperiod (EP) treatment between December 20 and the following April 10, and its effect on growth, endocrine changes, gonadal activation, and hair coat condition was investigated. In colts reared in Miyazaki, no effect of EP treatment was noted on the growth indices, including body weight (BW), height at withers (HW), girth, and cannon circumference (CC), whereas the BWs and CCs of fillies were significantly higher in the EP treatment group ...
Extracellular calcium regulates protein tyrosine phosphorylation through calcium-sensing receptor (CaSR) in stallion sperm.
Molecular reproduction and development    February 3, 2016   Volume 83, Issue 3 236-245 doi: 10.1002/mrd.22615
Macías-García B, Rocha A, González-Fernández L.Protein tyrosine phosphorylation (PY), a hallmark of sperm capacitation, is inhibited by extracellular calcium in stallion sperm. The objective of this study was to determine the presence and influence of the calcium-sensing receptor (CaSR) in this phenomenon. First, the presence of the CaSR was demonstrated in stallion sperm. We then tested its function in these gametes using its inhibitor NPS2143 or its agonist AC34356. Sperm were capacitated for 4 hr in modified Whitten's medium with 25 mM bicarbonate plus NPS2143 and 2.4 mM calcium or AC34356 alone, followed by analysis of PY. Inhibi...
Quantification of horse plasma proteins altered by xylazine using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 141-146 doi: 10.1294/jes.26.141
Mori M, Ichibangase T, Yamashita S, Kijima-Suda I, Kawahara M, Imai K.In the doping tests currently used in horse racing, prohibited substances or their metabolites are usually directly detected in urine or blood samples. However, despite their lasting pharmaceutical effects, some prohibited substances are rapidly eliminated from horse urine and blood, making them difficult to detect. Therefore, new indirect biomarkers for doping, such as plasma proteins that are increased by the prohibited substances, have recently attracted much attention. Here, a fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS) method was adopted for hor...
Seasonal changes in serum progesterone levels in Thoroughbred racehorses in training.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 135-139 doi: 10.1294/jes.26.135
Takahashi Y, Akai M, Murase H, Nambo Y.The objective of the present study was to verify the seasonal luteal activity of racehorses in training in Japan from March to August. We allocated 102 horses into a luteal activity group and non-luteal activity group. The luteal activity group included horses with serum progesterone levels that were consistently >1 ng/ml and changed by ± 1 ng/ml. In contrast, the progesterone levels of the non-luteal activity group were consistently <1 ng/ml. In late spring (from May 1 to June 30) and summer (from July 1 to August 31), the percentage of horses in the luteal activity group was significa...
A clinical case of equine fungal placentitis with reference to hormone profiles and ultrasonography.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 129-133 doi: 10.1294/jes.26.129
Murase H, Niwa H, Katayama Y, Sato F, Hada T, Nambo Y.Fungal placentitis is an infectious disease inducing abortion in pregnant mares. In the present report, we describe a field case of abortion caused by fungal placentitis with consecutive examinations. The progesterone level and combined thickness of the uterus and placenta (CTUP) were abnormal before the onset of clinical signs. Additionally, the estradiol level started to change before the appearance of clinical signs. Abnormal serum amyloid A values and an abnormal fetal heart rate were observed after the onset of clinical signs. The present report demonstrates that the progesterone level an...
Cryptosporidium parvum: From foal to veterinary students.
Veterinary parasitology    February 3, 2016   Volume 219 53-56 doi: 10.1016/j.vetpar.2016.02.001
Galuppi R, Piva S, Castagnetti C, Sarli G, Iacono E, Fioravanti ML, Caffara M.This paper describes the transmission of a zoonotic subtype of Cryptosporidium parvum between two foals hospitalized in an Equine Perinatology Unit (EPU) linked to an outbreak of cryptosporidiosis in veterinary students. Fecal specimens of 36 mares (105 samples) and 28 foals (122 samples) were subjected to Ziehl-Neelsen staining, nested PCR of 18S rDNA. Two foals tested positive for Cryptosporidium; PCR restriction fragment length polymorphism (PCR-RFLP) analysis and subtyping by nested PCR of the 60kDa glycoprotein (gp60) gene revealed C. parvum subtype IIdA23G1. The introduction of Cryptospo...
Influence of season on daytime behavioral activities of donkeys in the Northern Guinea Savanna zone of Nigeria.
Journal of equine science    February 3, 2016   Volume 26, Issue 4 105-111 doi: 10.1294/jes.26.105
Zakari FO, Ayo JO, Rekwot PI, Kawu MU.The present experiment was performed with the aim of investigating the effect of season on behavioral activities of donkeys during the rainy and harmattan seasons in the Northern Guinea zone of Nigeria. Sixteen apparently healthy donkeys were used as subjects and divided into four groups based on age. During each season, behavioral activities of each donkey were evaluated for three weeks using the focal animal sampling technique. The dry-bulb temperature (DBT), relative humidity (RH), and temperature-humidity index (THI) were obtained three times each day during the experimental period using s...
[EPIDEMIOLOGIC ANALYSIS OF OUTBREAKS OF DISEASES CAUSED BY AMERICAN EQUINE ENCEPHALITIS CAUSATIVE AGENTS IN ENDEMIC REGIONS].
Zhurnal mikrobiologii, epidemiologii i immunobiologii    February 3, 2016   Issue 5 103-110 
Petrov AA, Lebedev VN, Kulish VS, Pyshnaya NS, Stovba LF, Borisevich SV.Epidemiologic analysis of epidemic outbreaks caused by American equine encephalitis causative agents is carried out in the review. Eastern equine encephalomyelitis (EEE), Western equine encephalomyelitis (WEE) and Venezuela equine encephalomyelitis (VEE) viruses are etiologic agents of dangerous transmissive diseases that are usually accompanied by fever and neurologic symptoms. Among the New World alphaviruses, VEE virus has the most potential danger for humans and domestic animals. Currently, enzootic strains of VEE play an increasing role as etiologic agents of human diseases. Most of the V...
Idiopathic Fibrosis of the Tunica Muscularis of the Large Intestine in Five Horses with Colic.
Journal of comparative pathology    February 3, 2016   Volume 154, Issue 2-3 231-234 doi: 10.1016/j.jcpa.2016.01.001
Mair TS, Sherlock CE, Fews D, Harley R, Pearson GR.Histological evidence of fibrosis affecting the outer layer of the large intestinal tunica muscularis was identified in five of 32 horses affected by colic. In three cases, foci of pale eosinophilia and vacuolation of myocytes were observed. These findings are suggestive of a degenerative and fibrotic abnormality in the outer layer of the tunica muscularis of the large intestinal smooth muscle of some horses with colic.