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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.
Osteoprogenitor cell therapy in an equine fracture model.
Veterinary surgery : VS    July 13, 2012   Volume 41, Issue 7 773-783 doi: 10.1111/j.1532-950X.2012.01024.x
McDï¿® LA, Pack L, Lores M, Wright GM, Esparza-Gonzalez B, Masaoud E.To compare the efficacy of osteoprogenitors in fibrin glue to fibrin glue alone in bone healing of surgically induced ostectomies of the fourth metacarpal bones in an equine model. Methods: Experimental. Methods: Adult horses (n = 10). Methods: Segmental ostectomies of the 4th metacarpal bone (MC4) were performed bilaterally in 10 horses. There was 1 treatment and 1 control limb in each horse. Bone defects were randomly injected with either fibrin glue and osteoprogenitor cells or fibrin glue alone. Radiography was performed every week until the study endpoint at 12 weeks. After euthanasia, bo...
A pilot study on the corneal curvatures and ocular dimensions of horses less than one year of age.
Equine veterinary journal    July 12, 2012   Volume 45, Issue 2 256-258 doi: 10.1111/j.2042-3306.2012.00598.x
Townsend WM, Wasserman N, Jacobi S.Intraocular lenses (IOLs) have been implanted in adult equine eyes after cataract surgery. Foals and weanlings comprise a large proportion of those horses undergoing cataract surgery. Due to potential differences in the size and corneal curvature of the juvenile eye, it is not currently known whether implantation of adult IOLs is appropriate in foals and weanlings. The objective of the study was to measure the anterior chamber depth (ACD), central lens thickness (CLT), vitreous chamber depth (VCD), axial globe length (AGL) and corneal curvature of horses less than one year of age. The axial di...
The proximal aspect of the suspensory ligament in the horse: How precise are ultrasonographic measurements?
Equine veterinary journal    July 12, 2012   Volume 45, Issue 2 164-169 doi: 10.1111/j.2042-3306.2012.00597.x
Zauscher JM, Estrada R, Edinger J, Lischer CJ.To evaluate intra- and interobserver variability in ultrasonographic measurements of the proximal aspect of the suspensory ligament (PSL) in the horse. Objective: A minimum difference of ≥20% is required to differentiate reliably between physiological and pathological alterations related to dimensions. Methods: Two operators examined the PSL in all 4 limbs of 14 horses twice using different techniques and different probes with and without standoff pads. Measurements were taken from the longitudinal and transverse images. Inter- and intraoperator variability was evaluated using agreement indi...
Similar slow down in running speed progression in species under human pressure.
Journal of evolutionary biology    July 11, 2012   Volume 25, Issue 9 1792-1799 doi: 10.1111/j.1420-9101.2012.02563.x
Desgorces FD, Berthelot G, Charmantier A, Tafflet M, Schaal K, Jarne P, Toussaint JF.Running speed in animals depends on both genetic and environmental conditions. Maximal speeds were here analysed in horses, dogs and humans using data sets on the 10 best performers covering more than a century of races. This includes a variety of distances in humans (200-1500 m). Speed has been progressing fast in the three species, and this has been followed by a plateau. Based on a Gompertz model, the current best performances reach 97.4% of maximal velocity in greyhounds to 100.3 in humans. Further analysis based on a subset of individuals and using an 'animal model' shows that running spe...
Four loci explain 83% of size variation in the horse.
PloS one    July 11, 2012   Volume 7, Issue 7 e39929 doi: 10.1371/journal.pone.0039929
Makvandi-Nejad S, Hoffman GE, Allen JJ, Chu E, Gu E, Chandler AM, Loredo AI, Bellone RR, Mezey JG, Brooks SA, Sutter NB.Horse body size varies greatly due to intense selection within each breed. American Miniatures are less than one meter tall at the withers while Shires and Percherons can exceed two meters. The genetic basis for this variation is not known. We hypothesize that the breed population structure of the horse should simplify efforts to identify genes controlling size. In support of this, here we show with genome-wide association scans (GWAS) that genetic variation at just four loci can explain the great majority of horse size variation. Unlike humans, which are naturally reproducing and possess many...
The pathogenesis of tendon microdamage in athletes: the horse as a natural model for basic cellular research.
Journal of comparative pathology    July 11, 2012   Volume 147, Issue 2-3 227-247 doi: 10.1016/j.jcpa.2012.05.010
Patterson-Kane JC, Becker DL, Rich T.The equine superficial digital flexor tendon (SDFT) is a frequently injured structure that is functionally and clinically equivalent to the human Achilles tendon (AT). Both act as critical energy-storage systems during high-speed locomotion and can accumulate exercise- and age-related microdamage that predisposes to rupture during normal activity. Significant advances in understanding of the biology and pathology of exercise-induced tendon injury have occurred through comparative studies of equine digital tendons with varying functions and injury susceptibilities. Due to the limitations of in-...
Humeral stress remodelling locations differ in Thoroughbred racehorses training and racing on dirt compared to synthetic racetrack surfaces.
Equine veterinary journal    July 11, 2012   Volume 45, Issue 2 176-181 doi: 10.1111/j.2042-3306.2012.00596.x
Dimock AN, Hoffman KD, Puchalski SM, Stover SM.Veterinarians have observed a putative change in the location of humeral stress remodelling in Thoroughbred racehorses with change from dirt to synthetic racetrack surfaces. Objective: To determine whether the location and severity of humeral stress remodelling differs between Thoroughbred racehorses exercising on dirt and synthetic racetrack surfaces, the potential significance of different locations of stress remodelling, and the potential usefulness of scintigraphy for prevention of complete humeral fracture. Methods: Scintigraphic images of humeri from 841 Thoroughbred racehorses at 3 race...
Different outcomes between cyclophosphamide plus horse or rabbit antithymocyte globulin for HLA-identical sibling bone marrow transplant in severe aplastic anemia.
Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation    July 11, 2012   Volume 18, Issue 12 1876-1882 doi: 10.1016/j.bbmt.2012.07.004
Atta EH, de Sousa AM, Schirmer MR, Bouzas LF, Nucci M, Abdelhay E.The standard regimen for HLA-identical sibling bone marrow transplant (BMT) in severe aplastic anemia (SAA) is cyclophosphamide (Cy) and horse antithymocyte globulin (ATG). Horse ATG has been replaced by rabbit ATG in many countries due to the unavailability of the former product. This study was designed to assess if these ATG preparations are interchangeable in the preparative regimen for matched related BMT in SAA. Forty consecutive BMTs were retrospectively analyzed: 20 received Cy plus horse ATG and 20 received Cy plus rabbit ATG as the preparative regimen. Conditioning with rabbit ATG was...
Colloidal centrifugation of stallion semen results in a reduced rate of sperm DNA fragmentation.
Reproduction in domestic animals = Zuchthygiene    July 7, 2012   Volume 48, Issue 2 e23-e25 doi: 10.1111/j.1439-0531.2012.02140.x
Crespo F, Gosalvez J, Gutiérrez-Cepeda L, Serres C, Johnston SD.Stallion spermatozoa recovered and examined immediately after colloidal centrifugation resulted in a higher straight-line velocity (VSL) than sperm processed using direct conventional centrifugation (p = 0.000), but there was no differences in the progressive motility or sperm DNA fragmentation (SDF) as determined by the sperm chromatin dispersion assay. However, when centrifuged spermatozoa were incubated at 37 °C for 24 h to determine the rate of SDF (r-SDF), a lower r-SDF (p = 0.0011) was observed in those sperm recovered after colloidal separation (0.5 ± 0.1%/h) compared to direct (1.2 Â...
Comparative study of depth-dependent characteristics of equine and human osteochondral tissue from the medial and lateral femoral condyles.
Osteoarthritis and cartilage    July 7, 2012   Volume 20, Issue 10 1147-1151 doi: 10.1016/j.joca.2012.06.005
Malda J, Benders KE, Klein TJ, de Grauw JC, Kik MJ, Hutmacher DW, Saris DB, van Weeren PR, Dhert WJ.Articular cartilage defects are common after joint injuries. When left untreated, the biomechanical protective function of cartilage is gradually lost, making the joint more susceptible to further damage, causing progressive loss of joint function and eventually osteoarthritis (OA). In the process of translating promising tissue-engineering cartilage repair approaches from bench to bedside, pre-clinical animal models including mice, rabbits, goats, and horses, are widely used. The equine species is becoming an increasingly popular model for the in vivo evaluation of regenerative orthopaedic ap...
Comparison of bone marrow aspiration at the sternum and the tuber coxae in middle-aged horses. Delling U, Lindner K, Ribitsch I, Jülke H, Brehm W.The objective of this study was to compare bone marrow (BM) aspirates from the sternum and the tuber coxae of middle-aged horses. Bone marrow was obtained from the sternum and both tubera coxae of 12 healthy, 13-year-old geldings. Two different puncture techniques were used for the tuber coxae. The 2 syringes used for sternal sampling were evaluated separately. The mononuclear cell (MNC) fraction of the BM was isolated and the mesenchymal stem cells (MSCs) were culture-expanded. At the sternum, BM aspiration was always possible. Bone marrow aspiration at the tuber coxae required straight and d...
Specialization of tendon mechanical properties results from interfascicular differences.
Journal of the Royal Society, Interface    July 4, 2012   Volume 9, Issue 76 3108-3117 doi: 10.1098/rsif.2012.0362
Thorpe CT, Udeze CP, Birch HL, Clegg PD, Screen HR.Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when tested in vitro have a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles ...
Contrast-Enhanced Micro-Computed Tomography in Evaluation of Spontaneous Repair of Equine Cartilage.
Cartilage    July 1, 2012   Volume 3, Issue 3 235-244 doi: 10.1177/1947603511424173
Kulmala KA, Pulkkinen HJ, Rieppo L, Tiitu V, Kiviranta I, Brünott A, Brommer H, van Weeren R, Brama PA, Mikkola MT, Korhonen RK, Jurvelin JS....Contrast-enhanced computed tomography (CECT) has been introduced for the evaluation of cartilage integrity. Furthermore, CECT enables imaging of the structure and density of subchondral bone. In this laboratory study, we investigate the potential of microCECT to simultaneously image cartilage and subchondral bone for the evaluation of tissue healing. Methods: Osteochondral lesions (Ø = 6 mm) were surgically created in equine intercarpal joints (n = 7). After spontaneous healing for 12 months, the horses were sacrificed and osteochondral plugs (Ø = 14 mm), including the repair cartilage and a...
Genetic Diversity of mtDNA D-loop and Maternal Origin of Three Chinese Native Horse Breeds.
Asian-Australasian journal of animal sciences    July 1, 2012   Volume 25, Issue 7 921-926 doi: 10.5713/ajas.2011.11483
Zhang T, Lu H, Chen C, Jiang H, Wu S.In order to protect the genetic resource of native horse breeds, the genetic diversity of mitochondrial DNA (mtDNA) D-loop of three native horse breeds in western China were investigated. Forty-three 600 bp mtDNA D-loop sequences were analyzed by PCR and sequencing techniques, 33 unique haplotypes with 70 polymorphic sites were detected in these horses, which account for 11.67% of 600 bp sequence analyzed, showing the abundant genetic diversity of the three native horse breeds in western China. The Neighbour-Joining (NJ) phylogenetic tree based on 247 bp of 43 D-loop sequences demonstrated the...
RACK1, a clue to the diagnosis of cutaneous melanomas in horses.
BMC veterinary research    June 29, 2012   Volume 8 95 doi: 10.1186/1746-6148-8-95
Campagne C, Julé S, Bernex F, Estrada M, Aubin-Houzelstein G, Panthier JJ, Egidy G.Melanocytic proliferations are common in horses but the diagnosis of malignancy is not always straightforward. To improve diagnosis and prognosis, markers of malignancy are needed. Receptor for activated C kinase 1 (RACK1) protein may be such a marker. RACK1 was originally found to characterize malignant melanocytic lesions in the Melanoblastoma-bearing Libechov minipig (MeLiM) and, later, in human patients. Our purpose was to investigate the value of RACK1 in the classification of cutaneous melanocytic proliferations in horses. Results: Using immunofluorescence, we report here that both MITF ...
Effects of syringe type and storage conditions on results of equine blood gas and acid-base analysis.
American journal of veterinary research    June 29, 2012   Volume 73, Issue 7 979-987 doi: 10.2460/ajvr.73.7.979
Kennedy SA, Constable PD, Sen I, Couëtil L.To determine effects of syringe type and storage conditions on blood gas and acid-base values for equine blood samples. Methods: Blood samples obtained from 8 healthy horses. Methods: Heparinized jugular venous blood was equilibrated via a tonometer at 37°C with 12% O(2) and 5% CO(2). Aliquots (3 mL) of tonometer-equilibrated blood were collected in random order by use of a glass syringe (GS), general-purpose polypropylene syringe (GPPS), or polypropylene syringe designed for blood gas analysis (PSBGA) and stored in ice water (0°C) or at room temperature (22°C) for 0, 5, 15, 30, 60, or 120 ...
The fractal structure of equine articular cartilage.
Scanning    June 29, 2012   Volume 34, Issue 6 418-426 doi: 10.1002/sca.21026
Smyth PA, Rifkin RE, Jackson RL, Reid Hanson R.The naturally occurring structure of articular cartilage has proven to be an effective means for the facilitation of motion and load support in equine and other animal joints. Cartilage has been found to be a complex and dynamic medium, which has led to an incomplete understanding of the nature and operating mechanisms acting within a joint. Although cartilage has biphasic and triphasic properties, it is believed that the performance of equine articular joints is influenced by the surface roughness of the joint cartilage (Ateshian et al., '98; Chan et al., 2011; Yao and Unsworth, '93). Various...
Evaluation of the clinical efficacy of two partial intravenous anesthetic protocols, compared with isoflurane alone, to maintain general anesthesia in horses.
American journal of veterinary research    June 29, 2012   Volume 73, Issue 7 959-967 doi: 10.2460/ajvr.73.7.959
Nannarone S, Spadavecchia C.To compare the ability of 2 partial IV anesthesia (PIVA) techniques to maintain anesthesia, compared with isoflurane alone, in horses. Methods: 45 horses. Methods: Client-owned horses requiring general anesthesia for a variety of procedures of at least 1 hour's duration were randomly allocated to 3 groups (n = 15/group) that differed for the maintenance protocol. Anesthesia was maintained with isoflurane with a starting end-tidal isoflurane concentration of 1.3% (isoflurane group) or a concentration of 1% supplemented with an adjustable continuous infusion of guaifenesin-ketamine (IGK group) o...
Design and validation of a novel learning tool, the “Anato-Rug,” for teaching equine topographical anatomy.
Anatomical sciences education    June 29, 2012   Volume 5, Issue 5 256-263 doi: 10.1002/ase.1295
Braid F, Williams SB, Weller R.Recognition of anatomical landmarks in live animals (and humans) is key for clinical practice, but students often find it difficult to translate knowledge from dissection-based anatomy onto the live animal and struggle to acquire this vital skill. The purpose of this study was to create and evaluate the use of an equine anatomy rug ("Anato-Rug") depicting topographical anatomy and key areas of lung, heart, and gastrointestinal auscultation, which could be used together with a live horse to aid learning of "live animal" anatomy. Over the course of 2 weeks, 38 third year veterinary students were...
Activation of equine platelet-rich plasma: comparison of methods and characterization of equine autologous thrombin.
Veterinary surgery : VS    June 28, 2012   Volume 41, Issue 7 784-794 doi: 10.1111/j.1532-950X.2012.01016.x
Textor JA, Tablin F.To investigate and compare clinically relevant Platelet-rich plasma (PRP) activation methods. Methods: Experimental. Methods: PRP was prepared from 6 equine subjects. Activation of the PRP was performed by 4 methods (autologous thrombin, bovine thrombin, calcium chloride (CaCl(2) ), or freeze-thaw). The resultant PDGF-BB (where PDGF is platelet-derived growth factor) and TGFβ1 (where TGFβ is transforming growth factor beta) levels in PRP releasates were quantified by Enzyme-linked immunosorbent assay (ELISA) and compared. Growth factor contents were also compared between platelet-rich clots ...
Mitochondrial DNA D-loop sequence variation in maternal lineages of Iranian native horses.
Animal genetics    June 26, 2012   Volume 44, Issue 2 209-213 doi: 10.1111/j.1365-2052.2012.02389.x
Moridi M, Masoudi AA, Vaez Torshizi R, Hill EW.To understand the origin and genetic diversity of Iranian native horses, mitochondrial DNA (mtDNA) D-loop sequences were generated for 95 horses from five breeds sampled in eight geographical locations in Iran. Sequence analysis of a 247-bp segment revealed a total of 27 haplotypes with 38 polymorphic sites. Twelve of 19 mtDNA haplogroups were identified in the samples. The most common haplotypes were found within haplogroup X2. Within-population haplotype and nucleotide diversities of the five breeds ranged from 0.838 ± 0.056 to 0.974 ± 0.022 and 0.011 ± 0.002 to 0.021 ± 0.001 res...
Chimeric viruses containing the N-terminal ectodomains of GP5 and M proteins of porcine reproductive and respiratory syndrome virus do not change the cellular tropism of equine arteritis virus.
Virology    June 26, 2012   Volume 432, Issue 1 99-109 doi: 10.1016/j.virol.2012.05.022
Lu Z, Zhang J, Huang CM, Go YY, Faaberg KS, Rowland RR, Timoney PJ, Balasuriya UB.Equine arteritis virus (EAV) and porcine reproductive and respiratory syndrome virus (PRRSV) are members of family Arteriviridae; they are highly species specific and differ significantly in cellular tropism in cultured cells. In this study we examined the role of the two major envelope proteins (GP5 and M) of EAV and PRRSV in determining their cellular tropism. We generated three viable EAV/PRRSV chimeric viruses by swapping the N-terminal ectodomains of these two proteins from PRRSV IA1107 strain into an infectious cDNA clone of EAV (rMLVB4/5 GP5ecto, rMLVB4/5/6 Mecto and rMLVB4/5/6 GP5&Mect...
Stem/progenitor cells in non-lactating versus lactating equine mammary gland.
Stem cells and development    June 25, 2012   Volume 21, Issue 16 3055-3067 doi: 10.1089/scd.2012.0042
Spaas JH, Chiers K, Bussche L, Burvenich C, Van de Walle GR.The mammary gland is a highly regenerative organ that can undergo multiple cycles of proliferation, lactation, and involution. Based on the facts that (i) mammary stem/progenitor cells (MaSC) are proposed to be the driving forces behind mammary growth and function and (ii) variation exists between mammalian species with regard to physiological and pathological functioning of this organ, we believe that studying MaSC from different mammals is of great comparative interest. Over the years, important data has been gathered on MaSC of men and mice, although knowledge on MaSC in other mammals remai...
In vitro comparison of a single-layer (continuous Lembert) versus two-layer (simple continuous/Cushing) hand-sewn end-to-end jejunoileal anastomosis in normal equine small intestine.
Veterinary surgery : VS    June 25, 2012   Volume 41, Issue 5 589-593 doi: 10.1111/j.1532-950X.2012.00997.x
Lee WL, Epstein KL, Sherlock CE, Mueller PO, Eggleston RB.To compare in vitro physical and mechanical characteristics of 1-layer and 2-layer end-to-end jejunoileostomy. Methods: In vitro experimental study. Methods: Adult horses (n = 6). Methods: Harvested equine jejunum and ileum was used to create 1- and 2-layer end-to-end jejunoileostomy specimens. Construction time, bursting pressure, and relative lumen diameter (anastomosis diameter expressed as a percentage of the lumen diameter of adjacent jejunum and ileum) were compared. Construction time and relative lumen diameters were compared using a paired t-test. Bursting pressure for anastomoses and ...
Pedigrees as a source of information in mtDNA studies of dogs and horses.
Animal genetics    June 21, 2012   Volume 44, Issue 2 227-230 doi: 10.1111/j.1365-2052.2012.02388.x
Głażewska I, Prusak B, Gralak B.The goal of this study was to demonstrate the usefulness of pedigree data in studies of mitochondrial DNA diversity in dogs and horses. Pedigree information allows for precisely choosing animals with distinct haplotypes for analysis, makes it possible to find rare haplotypes present exclusively in single individuals and helps to evaluate haplotype frequencies at the present and in the past. Estimating founder contributions to gene pools enables evaluating the parts of gene pools observed with the help of mtDNA analysis. An important aspect is also the financial benefits: using pedigree data, r...
A simplified but robust method for the isolation of avian and mammalian muscle satellite cells.
BMC cell biology    June 21, 2012   Volume 13 16 doi: 10.1186/1471-2121-13-16
Baquero-Perez B, Kuchipudi SV, Nelli RK, Chang KC.Current methods of isolation of muscle satellite cells from different animal species are highly variable making inter-species comparisons problematic. This variation mainly stems from the use of different proteolytic enzymes to release the satellite cells from the muscle tissue (sometimes a single enzyme is used but often a combination of enzymes is preferred) and the different extracellular matrix proteins used to coat culture ware. In addition, isolation of satellite cells is frequently laborious and sometimes may require pre-plating of the cell preparation on uncoated flasks or Percoll cent...
Bone mineral density and bone mineral content of the bilateral first phalanges of the thoracic limbs in horses.
Polish journal of veterinary sciences    June 20, 2012   Volume 15, Issue 1 159-161 doi: 10.2478/v10181-011-0128-2
Dzierzecka M, Charuta A.The bone mineral density (BMD) and the bone mineral content (BMC) in the bone tissue of the bilateral first phalanges of horses' thoracic limbs were analysed. The research material consisted of isolated pastern bones derived from 22 horses. The research was conducted with the use of a Norland model Excell Plus densitometer (Fort Atkinson WI, USA), using affinited beam X-ray technology and an animal research programme (Research Scan, 3.9.6. version) at the following parameters: scanning resolution of 1.5 x 1.5 mm, scanning speed 60 mm/s. The differences between BMC and BMD values in bilateral f...
Parameters influencing prevalence and outcome of tendonitis in Thoroughbred and Arabian racehorses.
Polish journal of veterinary sciences    June 20, 2012   Volume 15, Issue 1 111-118 doi: 10.2478/v10181-011-0121-9
Kalisiak O.Flexor tendonitis and suspensory desmitis are among most prevalent musculoskeletal injuries observed in racehorses. The aim of this study was to determine which horse and race-related parameters can help to diminish the possibility of injury or--when injury has occurred--to evaluate the potential for the horse to continue a successful career after convalescence. Special attention was given to the comparison of Arabian and Thoroughbred racehorses. 187 horses with ultrasonographically visible lesions were included in the study. Following parameters were analyzed: structure (Superficial Digital F...
Short-term and long-term PQ, QT and R-R intervals’ variability at the resting condition and after exercise testing in healthy Anglo-Arabian horses.
Polish journal of veterinary sciences    June 20, 2012   Volume 15, Issue 1 55-59 doi: 10.2478/v10181-011-0114-8
Pasławska U, Zyśko D, Noszczyk-Nowak A, Pasławski R.The duration of electrocardiographic (ECG) parameters: PQ, QT and R-R intervals change during long-term and short-term observation as the consequence of the fluctuations in autonomic nervous system activity among others dependent on the exercise and resting. There is no data of horse breed influence on these parameters. The aim of the study was to assess the duration and the variability of the PQ, QT and R-R intervals in the resting conditions and after exercise testing in Anglo-Arabian horses. Methods: 27 healthy Anglo-Arabian horses aged 3.4 +/- 1.0 years (15 male, 12 female) had ECG examina...
Evidence of host adaptation in Lawsonia intracellularis infections.
Veterinary research    June 20, 2012   Volume 43, Issue 1 53 doi: 10.1186/1297-9716-43-53
Vannucci FA, Pusterla N, Mapes SM, Gebhart C.Lawsonia intracellularis is the causative agent of proliferative enteropathy, an endemic disease in pigs and an emerging concern in horses. Enterocyte hyperplasia is a common lesion in every case but there are differences regarding clinical and pathological presentations among affected species. We hypothesize that host susceptibility to L. intracellularis infection depends on the species of origin of the bacterial isolate. The objective of this study was to evaluate the susceptibilities of pigs and horses to L. intracellularis infection using either a porcine or an equine isolate. Methods: Twe...