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Topic:Veterinary Research

Veterinary research in horses encompasses the study of diseases, health management, and medical treatments specific to equine species. This field investigates various aspects of horse health, including infectious diseases, metabolic disorders, and musculoskeletal conditions. Researchers focus on understanding the pathophysiology of equine ailments, developing diagnostic tools, and evaluating therapeutic interventions. The study of horse health also involves examining preventive measures such as vaccination protocols and nutritional management to promote overall well-being. This page collects peer-reviewed research studies and scholarly articles that explore the diverse areas of veterinary science related to horses, providing insights into disease mechanisms, treatment strategies, and advancements in equine healthcare.
Association of low race performance with mtDNA haplogroup L3b of Australian thoroughbred horses.
Mitochondrial DNA. Part A, DNA mapping, sequencing, and analysis    January 27, 2017   Volume 29, Issue 2 323-330 doi: 10.1080/24701394.2016.1278535
Lin X, Zheng HX, Davie A, Zhou S, Wen L, Meng J, Zhang Y, Aladaer Q, Liu B, Liu WJ, Yao XK.Mitochondrial DNA (mtDNA) encodes the genes for respiratory chain sub-units that determine the efficiency of oxidative phosphorylation in mitochondria. The aim of this study was to determine if there were any haplogroups and variants in mtDNA that could be associated with athletic performance of Thoroughbred horses. The whole mitochondrial genomes of 53 maternally unrelated Australian Thoroughbred horses were sequenced and an association study was performed with the competition histories of 1123 horses within their maternal lineages. A horse mtDNA phylogenetic tree was constructed based on a t...
Occurrence of equine coital exanthema (ECE) in stallions in Japan and effectiveness of treatment with valacyclovir for ECE.
The Journal of veterinary medical science    January 26, 2017   Volume 79, Issue 3 632-635 doi: 10.1292/jvms.16-0511
Toishi Y, Tsunoda N, Kirisawa R.Equine coital exanthema (ECE) has been reported in many countries, but equine herpesvirus 3 (EHV-3) has been isolated only once in Japan. In 2015, symptoms of ECE were found, and EHV-3 was isolated in two stallions. Valacyclovir, an anti-herpesvirus agent, was administered orally. The stallions rested from mating for more than two weeks, causing enormous financial losses because of their high fees. This is the first study in which valacyclovir was administered for ECE. Though valacyclovir treatment did not shorten the duration of healing, the affected area did not expand after administration o...
Molecular characterization of Rhodococcus equi isolates from horses in Poland: pVapA characteristics and plasmid new variant, 85-kb type V.
BMC veterinary research    January 26, 2017   Volume 13, Issue 1 35 doi: 10.1186/s12917-017-0954-2
Witkowski L, Rzewuska M, Takai S, Chrobak-Chmiel D, Kizerwetter-Świda M, Feret M, Gawryś M, Witkowski M, Kita J.Rhodococcus equi is one of the most significant bacterial pathogens affecting foals up to 6 months of age worldwide. Rhodococcosis is present in Poland however information about molecular characterization of R. equi isolates is scarce. This study describes molecular characterization of Rhodococcus equi infection on 13 horse breeding farms in Poland between 2001 and 2012. Samples were collected by tracheobronchial aspiration from pneumonic foals or during necropsy. The R. equi isolates were genotyped by plasmid profiling and pulsed-field gel electrophoresis. Results: Totally, 58 R. equi isolat...
Evaluation of a Chemiluminescent Immunoassay for Measurement of Equine Insulin.
Journal of veterinary internal medicine    January 26, 2017   Volume 31, Issue 2 568-574 doi: 10.1111/jvim.14657
Carslake HB, Pinchbeck GL, McGowan CM.Many diagnostic tests for insulin dysregulation use reference intervals established with an insulin radioimmunoassay (RIA) that is no longer available. A chemiluminescent immunoassay (CLIA) is commonly used for the measurement of serum insulin concentration in clinical practice but requires further validation, especially at clinically relevant reference intervals. Objective: To evaluate the CLIA for measurement of equine insulin and compare it to the previously validated, but now unavailable RIA. Methods: Equine serum samples (n = 78) from clinical and experimental studies. Methods: In this ex...
Diagnosis of resistance alleles in codon 167 of the beta-tubulin (Cya-tbb-1) gene from third-stage larvae of horse cyathostomins.
Research in veterinary science    January 25, 2017   Volume 115 92-95 doi: 10.1016/j.rvsc.2017.01.019
Ishii JB, Arenal A, Felix A, Yoshitani U, Beech R, Molento MB.Anthelmintic resistance is a serious problem for the control of equine gastrointestinal nematodes. In the present survey, 173 third stage larvae of cyathostomins were investigated from three different locations for the presence of the resistant genotype at codon 167 of the beta-tubulin gene, as this is the most prevalent mutation. The larvae from the state of Parana (n=67), Sao Paulo (n=54) and Santa Catarina (n=52), showed 61.2; 31.5 and 38.5% of the heterozygous resistant genotype - TTC/TAC, respectively. An unpublished mutation at codon 172 that results in a serine (S) to threonine (T) subs...
Structure and Innervation of the Equine Supraspinous and Interspinous Ligaments.
Anatomia, histologia, embryologia    January 25, 2017   Volume 46, Issue 3 223-231 doi: 10.1111/ahe.12261
Ehrle A, Ressel L, Ricci E, Singer ER.Pain related to the osseous thoracolumbar spine is common in the equine athlete, with minimal information available regarding soft tissue pathology. The aims of this study were to describe the anatomy of the equine SSL and ISL (supraspinous and interspinous ligaments) in detail and to assess the innervation of the ligaments and their myofascial attachments including the thoracolumbar fascia. Ten equine thoracolumbar spines (T15-L1) were dissected to define structure and anatomy of the SSL, ISL and adjacent myofascial attachments. Morphological evaluation included histology, electron microscopy...
ECG of the Month.
Journal of the American Veterinary Medical Association    January 25, 2017   Volume 250, Issue 3 278-281 doi: 10.2460/javma.250.3.278
Pereira MM, Jung S, Wooldridge AA.No abstract available
Early volumetric changes after vertical augmentation of the atrophic posterior mandible with interpositional block graft versus onlay bone graft: A retrospective radiological study.
Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery    January 25, 2017   Volume 45, Issue 9 1438-1447 doi: 10.1016/j.jcms.2017.01.018
Barone A, Toti P, Menchini-Fabris GB, Felice P, Marchionni S, Covani U.The aim of this study was to evaluate volumetric and clinical outcomes of atrophic posterior mandibles treated with inlay or onlay bone grafting techniques. Methods: In posterior mandibles, alveolar ridges were treated either with interpositional equine cancellous bone block (inlay group) or with onlay autogenous bone block (onlay group). Bone volumes at baseline and at 4 months after surgery were measured by computed tomography. Results: A total of 20 subjects were enrolled in the present study: 10 in the inlay group and 10 in the onlay group. After surgery, atrophic posterior mandibles showe...
Sudden death in racehorses: postmortem examination protocol. Diab SS, Poppenga R, Uzal FA.In racehorses, sudden death (SD) associated with exercise poses a serious risk to jockeys and adversely affects racehorse welfare and the public perception of horse racing. In a majority of cases of exercise-associated sudden death (EASD), there are no gross lesions to explain the cause of death, and an examination of the cardiovascular system and a toxicologic screen are warranted. Cases of EASD without gross lesions are often presumed to be sudden cardiac deaths (SCD). We describe an equine SD autopsy protocol, with emphasis on histologic examination of the heart ("cardiac histology protocol...
Deletion of 2.7 kb near HOXD3 in an Arabian horse with occipitoatlantoaxial malformation.
Animal genetics    January 23, 2017   Volume 48, Issue 3 287-294 doi: 10.1111/age.12531
Bordbari MH, Penedo MCT, Aleman M, Valberg SJ, Mickelson J, Finno CJ.In the horse, the term occipitoatlantoaxial malformation (OAAM) is used to describe a developmental defect in which the first cervical vertebra (atlas) resembles the base of the skull (occiput) and the second cervical vertebra (axis) resembles the atlas. Affected individuals demonstrate an abnormal posture and varying degrees of ataxia. The homeobox (HOX) gene cluster is involved in the development of both the axial and appendicular skeleton. Hoxd3-null mice demonstrate a strikingly similar phenotype to Arabian foals with OAAM. Whole-genome sequencing was performed in an OAAM-affected horse (O...
Testosterone serum profile, semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment.
Reproduction in domestic animals = Zuchthygiene    January 23, 2017   Volume 52, Issue 2 335-343 doi: 10.1111/rda.12918
Waddington B, Penitente-Filho JM, Neves J, Pinho RO, Chaya AY, Maitan PP, Silveira CO, Neves MG, Guimarães S, de Carvalho GR, Guimarães JD.This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20-min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations ...
Assessment of tuber coxae bone biopsy in the standing horse.
Veterinary surgery : VS    January 23, 2017   Volume 46, Issue 3 396-402 doi: 10.1111/vsu.12603
Mitchell CF, Richbourg HA, Goupil BA, Gillett AN, McNulty MA.To describe a biopsy technique in standing horses with minimal morbidity that consistently provides a substantial bone biopsy with intact, undamaged architecture. Methods: Experimental, prospective study. Methods: Ten Thoroughbred horses. Methods: Biopsies were obtained from the tuber coxae of 10 sedated, standing horses using an oscillating saw. Bilateral biopsies, separated by 60 days, were evaluated with micro-computed tomography (microCT). The first biopsy was prepared for decalcified histology; the second for undecalcified histology. Both biopsies were evaluated qualitatively for histolog...
Expression of Toll-like receptors 2, 4 and 6 in different cell populations of the equine endometrium.
Veterinary immunology and immunopathology    January 22, 2017   Volume 185 7-13 doi: 10.1016/j.vetimm.2017.01.002
Schöniger S, Gräfe H, Schoon HA.Subfertility in mares is mainly caused by endometrial diseases. Alterations of Toll-like receptors (TLRs) are associated with endometrial disorders in women. This study investigated TLRs 2, 4 and 6 in the equine endometrium. Endometria of 21 mares were examined by histology, PCR and immunohistochemistry. Tissues from 2 mares were considered normal. The remaining showed endometritis, endometrosis and/or angiosclerosis. TLRs 2, 4 and 6 were expressed as transcripts and proteins in all endometria. Immunohistochemistry detected TLRs 2, 4 and 6 in mast cells, luminal and glandular epithelial cells,...
Presence and distribution of yeasts in the reproductive tract in healthy female horses.
Equine veterinary journal    January 22, 2017   Volume 49, Issue 5 614-617 doi: 10.1111/evj.12657
Azarvandi A, Khosravi AR, Shokri H, Talebkhan Garoussi M, Gharahgouzlou F, Vahedi G, Sharifzadeh A.Yeasts are commensal organisms found in the reproductive and gastrointestinal tracts, and on the skin and other mucosa in mammals. Objective: The purpose of this study was to isolate and identify yeast flora in the caudal reproductive tract in healthy female horses. Methods: Longitudinal study. Methods: A total of 453 samples were collected using double-guarded swabs from the vestibule, clitoral fossa and vagina in 151 horses. All samples were cultured on Sabouraud 4% dextrose agar and incubated at 35°C for 7-10 days. Isolates were identified according to their morphological characteristics a...
Longitudinal changes in serum catecholamines, dopamine, serotonin, ACTH and cortisol in pregnant Spanish mares.
Research in veterinary science    January 21, 2017   Volume 115 29-33 doi: 10.1016/j.rvsc.2017.01.020
Marcilla M, Muñoz A, Satué K.Systemic physiological changes required for placental and fetal development during pregnancy are associated with an activation of the sympathetic nervous system (SNS) and the hypothalamus-pituitary-adrenal axis (HPA) in women, but this fact has not been investigated in mares. Venous blood samples were taken monthly from 31 successful Spanish mares during the 11months of pregnancy. During the first 4months of pregnancy, adrenaline (AD), dopamine (DOPA) and ACTH increases, whereas 5-hydroxitryptamine (5-HT) decreased, and noradrenaline (NAD) and cortisol (CORT) did not change. Serum NAD increase...
Echocardiographic Assessment of Left Ventricular Function in Healthy Horses and in Horses with Heart Disease Using Pulsed-Wave Tissue Doppler Imaging.
Journal of veterinary internal medicine    January 21, 2017   Volume 31, Issue 2 556-567 doi: 10.1111/jvim.14641
Koenig TR, Mitchell KJ, Schwarzwald CC.Assessment of left ventricular (LV) function by tissue Doppler imaging (TDI) is not well established in horses with heart disease. Objective: To describe the use of pulsed-wave (PW) TDI for the assessment of LV function, establish reference intervals, investigate effects of mitral regurgitation (MR), aortic regurgitation (AR), and primary myocardial disease (MD), and provide proof of concept for the use of PW TDI in Warmblood horses with heart disease. Methods: Thirty healthy horses, 38 horses with MR, 25 with AR, 8 with MD. Methods: Echocardiograms were retrospectively analyzed. Reference int...
Morphological description of limbal epithelium: searching for stem cells crypts in the dog, cat, pig, cow, sheep and horse.
Veterinary research communications    January 21, 2017   Volume 41, Issue 2 169-173 doi: 10.1007/s11259-017-9676-y
Patruno M, Perazzi A, Martinello T, Blaseotto A, Di Iorio E, Iacopetti I.The cornea provides protection and transparency to the eye, allowing an optimal sharpness view. In some pathological conditions the cornea is able to regenerate thanks to the presence of a stem cells reservoir present at the level of the transition area between cornea and sclera (limbus). Corneal cell therapies in Veterinary Medicine are really limited due to the lacking of knowledge about the anatomy of the limbal area, the putative presence of stem cells and their identification in domestic species. The aim of this study was to provide an overview of the main distinctive structural features ...
Characterization of the complete mitochondrial genome of Setaria digitata (Nematoda: Setariidae) from China.
Journal of helminthology    January 20, 2017   Volume 91, Issue 6 772-776 doi: 10.1017/S0022149X16000912
Liu GH, Li JY, Zhu XQ.Setaria digitata is a filarial parasite that causes fatal cerebrospinal nematodiasis in goats, horses and sheep, resulting in substantial economic losses to livestock farmers. In the present study, the complete mitochondrial (mt) genome of S. digitata from China was determined, characterized and compared with that of S. digitata from Sri Lanka. The identity of the mt genomes was 98.3% between S. digitata from China and Sri Lanka, and the complete mt genome sequence of S. digitata from China was slightly shorter (25 bp) than that from Sri Lanka. For the 12 protein genes, this comparison reveal...
Histopathological features of endometritis eosinophilica in mares.
Histology and histopathology    January 20, 2017   Volume 32, Issue 11 1161-1173 doi: 10.14670/HH-11-872
Grimm AL, Schoon HA, Schöniger S.Equine endometritis eosinophilica (EE) is rarely described and its diagnostic criteria are not defined. The aim of this study was to characterize histological features of EE. A data base (1995-2013) was searched for biopsies with increased eosinophils. This study included all biopsies with this diagnosis and representative biopsies without this record. The definition of equine EE was based on criteria for EE in women and the results of the determination of physiological numbers of eosinophils within the equine endometrium. EE was diagnosed in 55 mares. Biopsies of 10 mares contained eosinophil...
Tissue resolved, gene structure refined equine transcriptome.
BMC genomics    January 20, 2017   Volume 18, Issue 1 103 doi: 10.1186/s12864-016-3451-2
Mansour TA, Scott EY, Finno CJ, Bellone RR, Mienaltowski MJ, Penedo MC, Ross PJ, Valberg SJ, Murray JD, Brown CT.Transcriptome interpretation relies on a good-quality reference transcriptome for accurate quantification of gene expression as well as functional analysis of genetic variants. The current annotation of the horse genome lacks the specificity and sensitivity necessary to assess gene expression especially at the isoform level, and suffers from insufficient annotation of untranslated regions (UTR) usage. We built an annotation pipeline for horse and used it to integrate 1.9 billion reads from multiple RNA-seq data sets into a new refined transcriptome. This equine transcriptome integrates eight d...
Influence of 2nd-degree AV blocks, ECG recording length, and recording time on heart rate variability analyses in horses.
Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology    January 20, 2017   Volume 19, Issue 2 160-174 doi: 10.1016/j.jvc.2016.10.006
Eggensperger BH, Schwarzwald CC.To assess the influence of 2nd-degree AV blocks (AVB) on RR interval-based heart rate variability (HRV) variables; to investigate the effect of using PP interval time series and of artifact filtering on HRV analyses; to investigate the influence of electrocardiogram (ECG) recording length and time of recording; and to calculate day-to-day variability and reference intervals of HRV variables. Methods: Thirty healthy adult horses. Methods: RR and PP interval time series were extracted from 10-h Holter ECGs and an automated filter was applied to the RR time series (RR). Time-domain HRV variables...
Identification of LukPQ, a novel, equid-adapted leukocidin of Staphylococcus aureus.
Scientific reports    January 20, 2017   Volume 7 40660 doi: 10.1038/srep40660
Koop G, Vrieling M, Storisteanu DM, Lok LS, Monie T, van Wigcheren G, Raisen C, Ba X, Gleadall N, Hadjirin N, Timmerman AJ, Wagenaar JA, Klunder HM....Bicomponent pore-forming leukocidins are a family of potent toxins secreted by Staphylococcus aureus, which target white blood cells preferentially and consist of an S- and an F-component. The S-component recognizes a receptor on the host cell, enabling high-affinity binding to the cell surface, after which the toxins form a pore that penetrates the cell lipid bilayer. Until now, six different leukocidins have been described, some of which are host and cell specific. Here, we identify and characterise a novel S. aureus leukocidin; LukPQ. LukPQ is encoded on a 45 kb prophage (ΦSaeq1) found i...
Undifferentiated embryonic cell transcription factor 1 (UTF1) and deleted in azoospermia-like (DAZL) expression in the testes of donkeys.
Reproduction in domestic animals = Zuchthygiene    January 20, 2017   Volume 52, Issue 2 264-269 doi: 10.1111/rda.12889
Lee YS, Jung HJ, Yoon MJ.Putative markers for each specific germ cell stage can be a useful tool to study the fate and functions of these cells. Undifferentiated embryonic cell transcription factor 1 (UTF1) is a putative marker for undifferentiated spermatogonia in humans, rats and horses. The deleted in azoospermia-like (DAZL) protein is also expressed by differentiated spermatogonia and primary spermatocytes in several species. However, whether the expression patterns of these molecular markers are identical and applicable to donkeys remains to be elucidated. The objective of this study was to investigate the expres...
Experimental investigation of the structural behavior of equine urethra.
Computer methods and programs in biomedicine    January 20, 2017   Volume 141 35-41 doi: 10.1016/j.cmpb.2017.01.012
Natali AN, Carniel EL, Frigo A, Fontanella CG, Rubini A, Avital Y, De Benedictis GM.An integrated experimental and computational investigation was developed aiming to provide a methodology for characterizing the structural response of the urethral duct. The investigation provides information that are suitable for the actual comprehension of lower urinary tract mechanical functionality and the optimal design of prosthetic devices. Methods: Experimental activity entailed the execution of inflation tests performed on segments of horse penile urethras from both proximal and distal regions. Inflation tests were developed imposing different volumes. Each test was performed accordin...
Detection of Equine Herpesvirus (EHV) -1, -2, -4 and -5 in Ethiopian Equids with and without Respiratory Problems and Genetic Characterization of EHV-2 and EHV-5 Strains.
Transboundary and emerging diseases    January 18, 2017   Volume 64, Issue 6 1970-1978 doi: 10.1111/tbed.12601
Negussie H, Gizaw D, Tesfaw L, Li Y, Oguma K, Sentsui H, Tessema TS, Nauwynck HJ.Infections with equine herpesviruses (EHVs) are widespread in equine populations worldwide. Whereas both EHV-1 and EHV-4 produce well-documented respiratory syndromes in equids, the contribution of EHV-2 and EHV-5 to disease of the respiratory tract is still enigmatic. This study describes the detection and genetic characterization of EHVs from equids with and without clinical respiratory disease. Virus-specific PCRs were used to detect EHV-1, -2, -4 and -5. From the total of 160 equids with respiratory disease, EHV-5 was detected at the highest prevalence (23.1%), followed by EHV-2 (20.0%), E...
Donor-Matched Comparison of Chondrogenic Potential of Equine Bone Marrow- and Synovial Fluid-Derived Mesenchymal Stem Cells: Implications for Cartilage Tissue Regeneration.
Frontiers in veterinary science    January 18, 2017   Volume 3 121 doi: 10.3389/fvets.2016.00121
Zayed M, Caniglia C, Misk N, Dhar MS.Mesenchymal stem cells (MSCs) have been demonstrated to be useful for cartilage tissue regeneration. Bone marrow (BM) and synovial fluid (SF) are promising sources for MSCs to be used in cartilage regeneration. In order to improve the clinical outcomes, it is recommended that prior to clinical use, the cellular properties and, specifically, their chondrogenic potential must be investigated. The purpose of this study is to compare and better understand the chondrogenic potential of equine bone marrow-derived mesenchymal stem cells (BMMSCs) and synovial fluid-derived mesenchymal stem cells (SFM...
Anti-inflammatory drugs decrease infection of brain endothelial cells with EHV-1 in vitro.
Equine veterinary journal    January 17, 2017   Volume 49, Issue 5 629-636 doi: 10.1111/evj.12656
Goehring LS, Brandes K, Ashton LV, Wittenburg LA, Olea-Popelka FJ, Lunn DP, Soboll Hussey G.Equine herpesvirus-associated myeloencephalopathy is the result of endothelial cell infection of the spinal cord vasculature with equine herpesvirus-1 (EHV-1) during cell-associated viraemia. Endothelial cell infection requires contact between infected peripheral blood mononuclear and endothelial cells. Inflammation generated during viraemia likely upregulates adhesion molecule expression on both cell types increasing contact and facilitating endothelial cell infection. Objective: Evaluating the role of anti-inflammatory drugs in decreasing endothelial cell infection with EHV-1. Methods: In vi...
Pharmacokinetics and selected pharmacodynamics of romifidine following low-dose intravenous administration in combination with exercise to quarter horses.
Journal of veterinary pharmacology and therapeutics    January 17, 2017   Volume 40, Issue 5 569-574 doi: 10.1111/jvp.12395
Knych HK, Stanley SD, McKemie DS, Steinmetz SJ.Romifidine is an alpha-2 adrenergic agonist used for sedation and analgesia in horses. As it is a prohibited substance, its purported use at low doses in performance horses necessitates further study. The primary goal of the study reported here was to describe the serum concentrations and pharmacokinetics of romifidine following low-dose administration immediately prior to exercise, utilizing a highly sensitive liquid chromatography-tandem mass spectrometry assay that is currently employed in many drug testing laboratories. An additional objective was to describe changes in heart rate and rhyt...
Identification of Arcanobacterium hippocoleae by MALDI-TOF MS analysis and by various genotypical properties.
Research in veterinary science    January 17, 2017   Volume 115 10-12 doi: 10.1016/j.rvsc.2017.01.006
Wickhorst JP, Sammra O, Hassan AA, Alssashen M, Lämmler C, Prenger-Berninghoff E, Erhard M, Metzner M, Paschertz K, Timke M, Abdulmawjood A.In the present study an Arcanobacterium hippocoleae strain isolated from a uterus swab of an apparently healthy mare could be identified by phenotypic properties, by MALDI-TOF MS analysis and genotypically by investigating the molecular targets 16S rDNA, 16S-23S rDNA intergenic spacer region and the genes encoding the β subunit of bacterial RNA polymerase (rpoB), elongation factor tu (tuf) and glyceraldehyde 3-phosphate dehydrogenase (gap). The presented data are one of the few reports about the species A. hippocoleae and might help to elucidate the role this species plays in infections of ho...
Prion replication without host adaptation during interspecies transmissions.
Proceedings of the National Academy of Sciences of the United States of America    January 17, 2017   Volume 114, Issue 5 1141-1146 doi: 10.1073/pnas.1611891114
Bian J, Khaychuk V, Angers RC, Fernández-Borges N, Vidal E, Meyerett-Reid C, Kim S, Calvi CL, Bartz JC, Hoover EA, Agrimi U, Richt JA, Castilla J....Adaptation of prions to new species is thought to reflect the capacity of the host-encoded cellular form of the prion protein (PrP) to selectively propagate optimized prion conformations from larger ensembles generated in the species of origin. Here we describe an alternate replicative process, termed nonadaptive prion amplification (NAPA), in which dominant conformers bypass this requirement during particular interspecies transmissions. To model susceptibility of horses to prions, we produced transgenic (Tg) mice expressing cognate PrP Although disease transmission to only a subset of infecte...