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Topic:Comparative Study

Comparative studies in equine research involve the systematic analysis of different horse breeds, management practices, or physiological responses to identify variations and similarities. These studies are instrumental in understanding how different factors influence health, performance, and behavior in horses. Common areas of comparison include genetic traits, nutritional requirements, disease resistance, and response to training. By evaluating these differences, researchers can develop targeted strategies for breeding, healthcare, and training. This page aggregates peer-reviewed research studies and scholarly articles that focus on the methodologies, findings, and implications of comparative studies in the context of equine science.
Polymorphisms of the equine major histocompatibility complex class II DRA locus.
Tissue antigens    July 13, 2004   Volume 64, Issue 2 173-179 doi: 10.1111/j.1399-0039.2004.00269.x
Brown JJ, Thomson W, Clegg P, Eyre S, Kennedy LJ, Matthews J, Carter S, Ollier WE.The full extent of the polymorphism of ELA-DRA in Equidae is not yet known. Given the apparent differences in DRA polymorphisms between Equidae and other species, the aims of this study were to more fully characterize ELA-DRA, determine the extent of gene polymorphism and establish the allele-frequency distribution. An allele reference panel for the second exon of ELA-DRA was established by sequence-based typing of 69 equine DNA samples consisting of various breeds of domestic horse (Equus caballus), together with donkeys (Equus asinus), Grant's zebras (Equus boehmi) and one onager (Equus hemi...
Endocrine-paracrine cells of the male urogenital apparatus: a comparative histochemical and immunohistochemical study in some domestic ungulates.
Anatomia, histologia, embryologia    July 9, 2004   Volume 33, Issue 4 225-232 doi: 10.1111/j.1439-0264.2004.00541.x
Arrighi S, Cremonesi F, Bosi G, Domeneghini C.Specimens of testis, excurrent duct including the male accessory glands and urethra, were studied in boars, bulls, horses and donkeys, in order to localize endocrine/paracrine cells. Silver impregnation methods were used to test the argentaffinity and/or argyrophilia of cells. Immunoreactivities to chromogranin A, 5-hydroxytryptamine, somatostatin, [met]- and [leu]- enkephalins, gastrin-releasing peptide, calcitonin gene-related peptide, neuropeptide Y, substance P, vasoactive intestinal peptide, beta-endorphin antisera were tested by a streptavidin-biotin method. In the testis, epididymis, du...
Association between race history and risk of superficial digital flexor tendon injury in Thoroughbred racehorses.
Journal of the American Veterinary Medical Association    July 9, 2004   Volume 225, Issue 1 90-93 doi: 10.2460/javma.2004.225.90
Takahashi T, Kasashima Y, Ueno Y.To determine whether race history, including the number of races and total race distance, was associated with risk of superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses in Japan. Methods: Matched case-control study. Methods: 515 Thoroughbred racehorses (case horses) that sustained an SDFT injury during training or racing in Japan during 2002 and 951 horses (control horses) without SDFT injury that were matched with case horses on the basis of age and month of the latest race. Methods: Variables related to race history were compared between case and control horses by mea...
Equine Infectious Anemia Virus (EIAV): what has HIV’s country cousin got to tell us?
Veterinary research    July 9, 2004   Volume 35, Issue 4 485-512 doi: 10.1051/vetres:2004020
Leroux C, Cadoré JL, Montelaro RC.Equine Infectious Anemia Virus (EIAV) is a lentivirus, of the Retrovirus family, with an almost worldwide distribution, infecting equids. It causes a persistent infection characterized by recurring febrile episodes associating viremia, fever, thrombocytopenia, and wasting symptoms. The disease is experimentally reproducible by inoculation of Shetland ponies or horses with EIAV pathogenic strains. Among lentiviruses, EIAV is unique in that, despite a rapid virus replication and antigenic variation, most animals progress from a chronic stage characterized by recurring peaks of viremia and fever ...
Detection of Anaplasma phagocytophilum in animals by real-time polymerase chain reaction.
APMIS : acta pathologica, microbiologica, et immunologica Scandinavica    July 6, 2004   Volume 112, Issue 4-5 239-247 doi: 10.1111/j.1600-0463.2004.apm11204-0503.x
Hulínská D, Langrová K, Pejcoch M, Pavlásek I.The aim of this study was to detect Anaplasma phagocytophilum in wild and domesticated animals and to identify the phylogenetic relationships of different strains of this bacterium. We adapted six published conventional methods targeting 16S fragments for real-time polymerase chain reaction. Initial screening of samples from 419 animals found 37 Anaplasma positives, later confirmed with several different primers and a TaqMan probe. We also performed DNA quantification and melting curve analysis. The nucleic acid of Anaplasma sp. was detected in a higher percentage of cases in members of the de...
Estimate of size and total number of neurons in superior cervical ganglion of rat, capybara and horse.
Anatomy and embryology    July 3, 2004   Volume 208, Issue 5 367-380 doi: 10.1007/s00429-004-0407-0
Ribeiro AA, Davis C, Gabella G.The superior (cranial) cervical ganglion was investigated by light microscopy in adult rats, capybaras (Hydrochaeris hydrochaeris) and horses. The ganglia were vascularly perfused, embedded in resin and cut into semi-thin sections. An unbiased stereological procedure (disector method) was used to estimate ganglion neuron size, total number of ganglion neurons, neuronal density. The volume of the ganglion was 0.5 mm3 in rats, 226 mm3 in capybaras and 412 mm3 in horses. The total number of neurons per ganglion was 18,800, 1,520,000 and 3,390,000 and the number of neurons per cubic millimetre was...
Quantification of Staphylococcus aureus adhesion to equine bone surfaces passivated with Plasmalyte and hyperimmune plasma.
Veterinary surgery : VS    July 3, 2004   Volume 33, Issue 4 376-381 doi: 10.1111/j.1532-950X.2004.04054.x
Bauer SM, Santschi EM, Fialkowski J, Clayton MK, Proctor RA.To quantify the adhesion of Staphylococcus aureus to 4 equine bone surfaces passivated in a balanced polyionic solution (Plasmalyte) or hyperimmune equine plasma (Polymune plasma). Methods: In vitro comparative study. Methods: Third metacarpal bone (MC3) surface explants from 9 equine cadavers. Methods: Approximately 1 cm(2) sections of periosteum were removed from MC3 and stapled to sterile stainless steel screens. Three bone surface explants were cut using a surgical saw to present 1 cm(2) surfaces of subperiosteal bone, cut cortical bone, or endosteum. Duplicate explants of each surface wer...
Comparison of systolic cardiac function before and after treatment of atrial fibrillation in horses with and without additional cardiac valve insufficiencies.
Veterinary research communications    June 30, 2004   Volume 28, Issue 4 317-329 doi: 10.1023/b:verc.0000026672.25856.0a
Gehlen H, Stadler P.Clinical, electrocardiographic and echocardiographic examinations were conducted before therapy and 4 days after conversion to normal sinus rhythm in 15 horses with a history of atrial fibrillation of 2-6 months duration. Seven horses showed no other signs of cardiac disease. Four horses suffered additionally from mitral valve insufficiency, while six horses had aortic valve insufficiency, including two of the four horses with mitral valve insufficiency, but none had signs of congestive heart failure. Doppler echocardiographic estimates of various variables were made for assessment of systolic...
Gene expression in the spermatogenically inactive “dark” and maturing “light” testicular tissues of the prepubertal colt.
Journal of andrology    June 30, 2004   Volume 25, Issue 4 535-544 doi: 10.1002/j.1939-4640.2004.tb02824.x
Ing NH, Laughlin AM, Varner DD, Welsh TH, Forrest DW, Blanchard TL, Johnson L.In the testis of the 1.5-year-old horse, spermatogenesis initiates locally in grossly light, central areas that contrast with grossly dark, peripheral areas that are as yet inactive in spermatogenesis. Gene expression was compared between "light" and "dark" tissues of 1.5-year-old horse testes to identify mechanisms important to the initiation of spermatogenesis. Microarrays containing human cDNAs were used to assess expression levels of 9132 genes simultaneously in matched pairs of dark and light testis tissues from 3 prepubertal colts. In all 3 analyses, dysferlin (DYS), down-regulated in ov...
Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging.
Journal of veterinary medicine. A, Physiology, pathology, clinical medicine    June 25, 2004   Volume 51, Issue 3 143-149 doi: 10.1111/j.1439-0442.2004.00615.x
Hevesi A, Stanek Ch, Garamvolgyi R, Petrasi Z, Bogner P, Repa I.Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues...
Tracing axons of peripheral nerves in rats: a potential technique to study the equine recurrent laryngeal nerve.
Journal of investigative surgery : the official journal of the Academy of Surgical Research    June 19, 2004   Volume 17, Issue 3 151-162 doi: 10.1080/08941930490446937
Velde K, Ross MW, Orsini JA, Parente EJ, Foley B, Richardson DW, Miselis RR.To study the fascicular anatomy of peripheral nerves, three different groups of retrograde axonal tracers were evaluated: fluorophores, horseradish peroxidase conjugated to subunit B of cholera toxin (CT-HRP), and adeno-associated virus (AAV). The hindlimb nerves in rats served as a model to identify the most efficient tracer in regard to labeling axons within peripheral nerves. The rat's tibial and common peroneal nerves were injected with the different tracers and the sciatic nerve was subsequently examined for evidence of labeled axons. The CT-HRP clearly provided the best results in this r...
A detailed physical map of the horse Y chromosome.
Proceedings of the National Academy of Sciences of the United States of America    June 14, 2004   Volume 101, Issue 25 9321-9326 doi: 10.1073/pnas.0403011101
Raudsepp T, Santani A, Wallner B, Kata SR, Ren C, Zhang HB, Womack JE, Skow LC, Chowdhary BP.We herein report a detailed physical map of the horse Y chromosome. The euchromatic region of the chromosome comprises approximately 15 megabases (Mb) of the total 45- to 50-Mb size and lies in the distal one-third of the long arm, where the pseudoautosomal region (PAR) is located terminally. The rest of the chromosome is predominantly heterochromatic. Because of the unusual organization of the chromosome (common to all mammalian Y chromosomes), a number of approaches were used to crossvalidate the results. Analysis of the 5,000-rad horse x hamster radiation hybrid panel produced a map spannin...
Effects of trimethoprim-sulfadiazine on thyroid function of horses.
Journal of veterinary internal medicine    June 11, 2004   Volume 18, Issue 3 370-373 doi: 10.1892/0891-6640(2004)18<370:eototf>2.0.co;2
Rothschild CM, Hines MT, Breuhaus B, Gay J, Sellon DC.Trimethoprim-sulfadiazine was administered to horses in a randomized, placebo controlled study to determine the effects of potentiated sulfonamides on thyroid function in normal horses. The treatment group included eight horses that received trimethoprim-sulfadiazine mixed with molasses orally at 30 mg/kg once daily for eight weeks. The control group included 8 horses that received an oral placebo (flour mixed with molasses) once daily for the same period. Thyroid function was evaluated prior to initiation of treatment and after 8 weeks of treatment. Serum concentrations of total and free trii...
Comparative study of the dynamics of follicular waves in mares and women.
Biology of reproduction    June 9, 2004   Volume 71, Issue 4 1195-1201 doi: 10.1095/biolreprod.104.031054
Ginther OJ, Gastal EL, Gastal MO, Bergfelt DR, Baerwald AR, Pierson RA.Deviation in growth rates of the follicles of the ovulatory wave begins at the end of a common growth phase and is characterized by continued growth of the developing dominant follicle (F1) and regression of the largest subordinate follicle (F2). Follicle diameters during an interovulatory interval were compared between 30 mares and 30 women, using similar methods for collecting and analyzing data. Follicles were tracked and measured daily by ultrasonography. Diameter at follicle emergence (mares, 13 mm; women, 6 mm) and the required minimal attained diameter for assessment of follicles (mares...
Characterization and localization of membrane vesicles in ejaculate fractions from the ram, boar and stallion.
Reproduction in domestic animals = Zuchthygiene    June 9, 2004   Volume 39, Issue 3 173-180 doi: 10.1111/j.1439-0531.2004.00499.x
Ghaoui Rel-H, Thomson PC, Evans G, Maxwell WM.Membrane vesicles, separated by differential centrifugation from the seminal plasma, were detected in the sperm-rich ejaculate fractions of four boars and three stallions, and in the whole ejaculates of seven rams. The volume and percentage of vesicles, determined by a stereological technique, were higher in the sperm-rich than in the post-sperm-rich fractions of the boar and stallion ejaculates, and no vesicles were detected in the pre sperm-rich fractions. Vesicles were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). For boar, stallion and ram semen...
Postnatal insulin secretion and sensitivity after manipulation of fetal growth by embryo transfer in the horse.
The Journal of endocrinology    June 3, 2004   Volume 181, Issue 3 459-467 doi: 10.1677/joe.0.1810459
Forhead AJ, Ousey JC, Allen WR, Fowden AL.This study examined the effects of intrauterine growth on insulin secretion and resistance in newborn foals. Embryo transfer between small pony and large Thoroughbred mares was used to produce four groups of foals with different birth weights (pony in pony n=7; pony in Thoroughbred n=7; Thoroughbred in Thoroughbred n=8; Thoroughbred in pony n=8). On day 2 after birth, glucose (0.5 g/kg) was administered intravenously to the foal and blood samples were taken for 2 h to determine plasma glucose and insulin concentrations. On day 3, insulin sensitivity was assessed by giving insulin (0.75 U/kg i....
[Concentrations of L-carnitine and parameters of lipid metabolism during estrus in broodmares].
DTW. Deutsche tierarztliche Wochenschrift    June 3, 2004   Volume 111, Issue 4 147-150 
Wittek T, Sobiraj A.In the present study the concentrations of L-carnitine (total carnitine, free carnitine, and acyl carnitine) and several parameters of the lipid metabolism were measured during the estrus in 10 broodmares. The carnitine concentrations varied in a wide range between the mares. The differences of the mean carnitine concentrations during the estrus did not reach the level of significance (P < 0.05). There was no relationship between the concentrations of total and free carnitine to the follicle size; however, the concentration of acyl carnitine was significantly correlated (r = -0.42). Because...
Isolation from the horse genome of a new DNA transposon belonging to the Tigger family.
Mammalian genome : official journal of the International Mammalian Genome Society    June 1, 2004   Volume 15, Issue 5 399-403 doi: 10.1007/s00335-004-3040-6
Paulis M, Moralli D, Bensi M, De Carli L, Raimondi E.Tigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Souther...
Absence of the functional Myosin heavy chain 2b isoform in equine skeletal muscles.
Zoological science    June 1, 2004   Volume 21, Issue 5 589-596 doi: 10.2108/zsj.21.589
Chikuni K, Muroya S, Nakajima I.Nucleotide sequences which included the full coding region for three types of myosin heavy chain (MyHC) isoforms were determined from equine skeletal muscles. The deduced amino acid sequences were 1937, 1938, and 1935 residues for the MyHC-2a, -2x, and -slow, respectively. No MyHC-2b isoform was amplified from the equine muscle cDNA except for one pseudogene fragment. One nucleotide was inserted in the coding region of the equine pseudogene product, a minute amount of which was expressed in the skeletal muscle. The 596 bp sequence of the equine MyHC pseudogene was categorized into the MyHC-2b ...
Evaluation and comparison of an indirect fluorescent antibody test for detection of antibodies to Sarcocystis neurona, using serum and cerebrospinal fluid of naturally and experimentally infected, and vaccinated horses.
The Journal of parasitology    May 29, 2004   Volume 90, Issue 2 379-386 doi: 10.1645/GE-3263
Duarte PC, Daft BM, Conrad PA, Packham AE, Saville WJ, MacKay RJ, Barr BC, Wilson WD, Ng T, Reed SM, Gardner IA.The objectives of this study were to evaluate the accuracy of the indirect fluorescent antibody test (IFAT) using serum and cerebrospinal fluid (CSF) of horses naturally and experimentally infected with Sarcocystis neurona, to assess the correlation between serum and CSF titers, and to determine the effect of S. neurona vaccination on the diagnosis of infection. Using receiver-operating characteristic analysis, the areas under the curve for the IFAT were 0.97 (serum) and 0.99 (CSF). Sensitivity and specificity were 83.3 and 96.9% (serum, cutoff 80) and 100 and 99% (CSF, cutoff 5), respectively...
Comparison of pressure within the corpus spongiosum penis during urination between geldings and stallions.
Equine veterinary journal    May 28, 2004   Volume 36, Issue 4 362-364 doi: 10.2746/0425164044890571
Taintor J, Schumacher J, Schumacher J, Purohit R, DeGraves F, Sartin E.No abstract available
Detection of West Nile virus using formalin fixed paraffin embedded tissues in crows and horses: quantification of viral transcripts by real-time RT-PCR.
Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology    May 28, 2004   Volume 30, Issue 4 320-325 doi: 10.1016/j.jcv.2004.01.003
Tewari D, Kim H, Feria W, Russo B, Acland H.West Nile virus (WNV) RNA was quantified in WNV infected crows and horses with the help of a real-time reverse transcriptase-PCR assay. A 5' nuclease assay, based on NS5 gene detection with a fluorescent probe was used for quantifying WNV RNA using formalin fixed paraffin embedded tissue specimens. Quantitative detection of WNV RNA showed the presence of a higher amount of the viral RNA in crow tissues compared to equine tissues and these results correlated well with the detection of WNV antigen by immunostaining. In crows, the highest amount of virus was seen in the intestine and in horses in...
Follicle profile and plasma gonadotropin concentration in pubertal female ponies.
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas    May 27, 2004   Volume 37, Issue 6 913-922 doi: 10.1590/s0100-879x2004000600018
Nogueira GP.Twelve female ponies were examined daily for 30 days and classified as ovulating (OV; N = 6; 197 +/- 6 kg) or prepubertal (PP; N = 6; 196 +/- 9 kg). Follicles were detected by ultrasound and gonadotropins quantified by radioimmunoassay. The mean diameter of the largest follicles was significantly larger in OV (38 +/- 1 mm) than in PP (26 +/- 2 mm) but there was no difference between groups in the size of the second largest follicle. There were more small follicles (29 mm than the OV fillies. Follicle-stimulating hormone (FSH) levels did not differ between groups but PP fillies had lower lutein...
Sirius red is able to selectively stain eosinophil granulocytes in bovine, ovine and equine cervical tissue.
Anatomia, histologia, embryologia    May 18, 2004   Volume 33, Issue 3 180-182 doi: 10.1111/j.1439-0264.2004.00532.x
Wehrend A, Hetzel U, Huchzermeyer S, Klein C, Bostedt H.The aim of the present study was to examine the suitability of sirius red staining for selective light microscopic demonstration of eosinophil granulocytes in cervical tissue of mares, cows and sheep. For this purpose, tissue was fixed in 4% neutral buffered formol or in Bouin's solution. Paraffin sections of 5-microm thickness were stained with sirius red. In cows, mares and sheep a selective distinction of eosinophilic infiltration is successful after both fixation methods.
Desmoplakin and Plakoglobin–specific markers of lymphatic vessels in the skin?
Anatomia, histologia, embryologia    May 18, 2004   Volume 33, Issue 3 168-171 doi: 10.1111/j.1439-0264.2004.00529.x
Fedele C, Berens D, Rautenfeld V, Pabst R.Monoclonal antibodies against Desmoplakin and Plakoglobin were tested for their suitability as specific markers of lymphatic vessels. The tissue samples were taken from horse skin in an attempt to establish the horse as a model for human lymphatic diseases. To obtain a clear, positive identification of blood and lymphatic vessels, immunohistochemical staining with antibodies against vascular endothelial growth factor receptor 3 (VEGFR-3) and platelet endothelial adhesion molecule (PECAM-1, CD31), was compared with Desmoplakin and Plakoglobin. Because anti-VEGFR-3 is specific for lymphatic vess...
Comparison of two laparoscopic treatments for experimentally induced abdominal adhesions in pony foals.
American journal of veterinary research    May 15, 2004   Volume 65, Issue 5 681-686 doi: 10.2460/ajvr.2004.65.681
Lansdowne JL, Bouré LP, Pearce SG, Kerr CL, Caswell JL.To compare laparoscopic dissection with-laparoscopic dissection combined with abdominal instillation of ferric hyaluronate gel for the treatment of experimentally induced adhesions in pony foals. Methods: 12 healthy pony foals. Methods: A serosal abrasion method was used to create adhesions at 4 sites on the jejunum (day 0). At day 7 laparoscopy was performed and the adhesions observed in each foal were recorded. In group-1 foals (n = 6), the adhesions were separated laparoscopically (treatment 1). In group-2 foals (n = 6), 300 mL of 0.5% ferric hyaluronate gel was infused into the abdomen aft...
Assessment of apoptosis in epidermal lamellar cells in clinically normal horses and those with laminitis.
American journal of veterinary research    May 15, 2004   Volume 65, Issue 5 578-585 doi: 10.2460/ajvr.2004.65.578
Faleiros RR, Stokes AM, Eades SC, Kim DY, Paulsen DB, Moore RM.To determine and compare the number, type, location, and distribution of apoptotic epidermal cells in the laminae of clinically normal horses and horses with laminitis. Methods: Formalin-fixed samples of digital lamellar tissue from 47 horses (including clinically normal horses [controls; n = 7], horses with acute [4] and chronic [7] naturally acquired laminitis, and horses with black walnut extract-induced [11] or carbohydrate overload-induced [18] laminitis). Methods: Blocks of paraffin-embedded lamellar tissues were stained for DNA fragmentation with the terminal deoxynucleotidyl transferas...
Evaluation of a sensor-based system of motion analysis for detection and quantification of forelimb and hind limb lameness in horses.
American journal of veterinary research    May 15, 2004   Volume 65, Issue 5 665-670 doi: 10.2460/ajvr.2004.65.665
Keegan KG, Yonezawa Y, Pai PF, Wilson DA, Kramer J.To compare a sensor-based accelerometer-gyroscopic (A-G) system with a video-based motion analysis system (VMAS) technique for detection and quantification of lameness in horses. Methods: 8 adult horses. Methods: 2 horses were evaluated once, 2 had navicular disease and were evaluated before and after nerve blocks, and 4 had 2 levels of shoe-induced lameness, alternatively, in each of 4 limbs. Horses were instrumented with an accelerometer transducer on the head and pelvis, a gyroscopic transducer on the right forelimb and hind feet, and a receiver-transmitter. Signals from the A-G system were...
Modulation of the cytokine responses in equine macrophages following TACE-inhibition.
Veterinary immunology and immunopathology    May 12, 2004   Volume 99, Issue 3-4 237-243 doi: 10.1016/j.vetimm.2004.01.005
Wijnker JJ, Bull S, Van Dijk P, Veenman JN, Rutten VP, Klein WR, Fink-Gremmels J.The detrimental effects of the pro-inflammatory cytokine TNF-alpha during equine acute abdominal disease are well known. Its pivotal role in many human diseases has led to various in-depth studies regarding its release mechanism, in particular by TNF-alpha converting enzyme (TACE). In this study we investigated the inhibitory effect of a TACE-inhibitor on cytokine release (TNF-alpha, IL-1alpha and IL-6) in three different cell models, including U937 cells, a recently established equine macrophage cell line, known as eCAS, and primary equine PBMC. The aim was to show the similarity of TNF-alpha...
Equine cardiovascular pathology: an overview.
Animal health research reviews    May 12, 2004   Volume 4, Issue 2 109-129 doi: 10.1079/ahr200353
Buergelt CD.The few data collections that evaluate the involvement of organ systems in horse diseases are in agreement that the locomotor, gastrointestinal and nervous systems are the sites of primary disease in the vast majority of sick horses. When compared with diseases of these organ systems, equine cardiovascular diseases occur infrequently. The most detailed and comprehensive survey of equine cardiac pathology was reported in 1972 by Else and Holmes, who summarized the gross and microscopic cardiac findings from 1500 abattoir horses. This paper reviews the pathology of the cardiovascular diseases ty...