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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.
Relationships among stallion fertility and semen traits using estimated breeding values of German Warmblood stallions.
Theriogenology    October 19, 2016   Volume 89 68-71 doi: 10.1016/j.theriogenology.2016.10.011
Gottschalk M, Sieme H, Martinsson G, Distl O.A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm (r = 0.36). EBV-PAT was considered in three classes with stallions 1 SD below (<80), around (80-120), and above (>120) the popu...
Neutral solute transport across osteochondral interface: A finite element approach.
Journal of biomechanics    October 19, 2016   Volume 49, Issue 16 3833-3839 doi: 10.1016/j.jbiomech.2016.10.015
Arbabi V, Pouran B, Weinans H, Zadpoor AA.Investigation of the solute transfer across articular cartilage and subchondral bone plate could nurture the understanding of the mechanisms of osteoarthritis (OA) progression. In the current study, we approached the transport of neutral solutes in human (slight OA) and equine (healthy) samples using both computed tomography and biphasic-solute finite element modeling. We developed a multi-zone biphasic-solute finite element model (FEM) accounting for the inhomogeneity of articular cartilage (superficial, middle and deep zones) and subchondral bone plate. Fitting the FEM model to the concentra...
Immune-modulating properties of horse milk administered to mice sensitized to cow milk.
Journal of dairy science    October 19, 2016   Volume 99, Issue 12 9395-9404 doi: 10.3168/jds.2016-11499
Fotschki J, Szyc AM, Laparra JM, Markiewicz LH, Wróblewska B.The aim of this study was to examine immune adaptive changes, the expression of innate biomarkers and variations in intestinal microbiota composition after horse-milk administration in BALB/c mice, which were sensitized intraperitoneally using cow β-lactoglobulin and α-casein with aluminum adjuvant. We measured serum antibody IgE levels and the expression of MCP-1, IL-4, and TNF-α in duodenal samples. Changes in immune cell populations in peripheral blood were quantified using flow cytometry, and intestinal microbiota composition was assessed using real-time PCR. We found that horse-milk ad...
Filarial infection caused by Onchocerca boehmi (Supperer, 1953) in a horse from Italy.
Parasitology research    October 19, 2016   Volume 116, Issue 1 191-198 doi: 10.1007/s00436-016-5277-x
Lia RP, Mutafchiev Y, Veneziano V, Giannelli A, Abramo F, Santoro M, Latrofa MS, Cantacessi C, Martin C, Otranto D, Bertuglia A, Riccio B.Equids can be infected by a range of skin-dwelling filarial nematodes, including four species of the genus Onchocerca. Current literature on equine onchocercosis is fragmentary and often limited to isolated case reports. The present study aimed to describe a clinical case of equine onchocercosis caused by Onchocerca boehmi (Supperer, 1953) (syn. Elaeophora boehmi) in an 8-year-old gelding Belgian show jumper from northern Italy. The horse was presented with a firm and painless mass on the proximal third of the right metacarpal region. Ultrasound examination showed a peritendinous enlargement a...
Ectopic Trophoblast Allografts in the Horse Resist Destruction by Secondary Immune Responses.
Biology of reproduction    October 19, 2016   Volume 95, Issue 6 135 doi: 10.1095/biolreprod.115.137851
Brosnahan MM, Silvela EJ, Crumb J, Miller DC, Erb HN, Antczak DF.Invasive trophoblast from Day 34 horse conceptuses survives in extrauterine sites in allogeneic recipients that are immunologically naive to donor major histocompatibility complex class I antigens. The ectopic trophoblast retains its in utero characteristics, including similar lifespan, physiologic effect of its secreted product (equine chorionic gonadotropin) upon the recipient's ovaries, and induction of host immune responses. Immunologic memory has not been considered previously in this experimental system. We hypothesized that primary exposure to ectopic trophoblast would affect the recipi...
Circulating miRNAs as Potential Alternative Cell Signaling Associated with Maternal Recognition of Pregnancy in the Mare.
Biology of reproduction    October 19, 2016   Volume 95, Issue 6 124 doi: 10.1095/biolreprod.116.142935
Klohonatz KM, Cameron AD, Hergenreder JR, da Silveira JC, Belk AD, Veeramachaneni DN, Bouma GJ, Bruemmer JE.During early pregnancy, the conceptus and mare communicate to establish pregnancy. Cell-secreted vesicles (e.g., exosomes) have been reported in serum. Exosomes contain bioactive materials, such as miRNA, that can mediate cell responses. We hypothesized that a) exosomes are present in mare circulation and quantity varies with pregnancy status, b) exosomes contain miRNAs unique to pregnancy status, and c) miRNAs target pathways in endometrium based upon pregnancy status of the mare. First, serum samples were obtained from mares in a crossover design, with each mare providing samples from a preg...
Short-term treatment of equine wounds with orf virus IL-10 and VEGF-E dampens inflammation and promotes repair processes without accelerating closure. Bodaan CJ, Wise LM, Wakelin KA, Stuart GS, Real NC, Mercer AA, Riley CB, Theoret C.Healing is delayed in limb wounds relative to body wounds of horses, partly because of sustained inflammation and inefficient angiogenesis. In laboratory animals, proteins derived from orf virus modulate these processes and enhance healing. We aimed to compare immune cell trafficking and the inflammatory, vascular, and epidermal responses in body and limb wounds of horses and then to investigate the impact of orf virus interleukin-10 and vascular endothelial growth factor-E on these processes. Standardized excisional wounds were created on the body and forelimb of horses and their progression ...
Epidemiologic analysis of a sarcoid outbreak involving 12 of 111 donkeys in Northern Italy.
Veterinary microbiology    October 17, 2016   Volume 196 85-92 doi: 10.1016/j.vetmic.2016.10.021
Equine sarcoids develop upon bovine papillomavirus type 1 or 2 (BPV1, BPV2) infection in conjunction with trauma and represent the most common tumour disease in horses and other equids, including donkeys. In face of a sarcoid outbreak involving 12 of 111 donkeys and mules at the 'Rifugio degli Asinelli', a subsidiary charity organization of The Donkey Sanctuary, non-invasively collected sample material including crusts, dandruff, swabs and hair roots was collected from sarcoid-affected and 26 healthy donkeys, as well as dandruff from a grooming kit and tabanids caught from or in the vicinity o...
Acute phase protein haptoglobin as inflammatory marker in serum and synovial fluid in an equine model of arthritis.
Veterinary immunology and immunopathology    October 17, 2016   Volume 182 74-78 doi: 10.1016/j.vetimm.2016.10.005
Barrachina L, Remacha AR, Soler L, García N, Romero A, Vázquez FJ, Vitoria A, Álava MÁ, Lamprave F, Rodellar C.Acute phase proteins are useful inflammatory markers in horses. Haptoglobin (Hp) serum level is increased in horses undergoing different inflammatory processes, including arthritis. However, Hp concentration has not been assessed in inflammatory synovial fluid (SF). The aim of the present study was to investigate the Hp response in serum and SF in horses undergoing experimentally induced arthritis. For this purpose, serum and SF samples were collected from 12 animals before amphotericin B-induced arthritis was created (T0, healthy) and 15days after the lesion induction (T1, joint inflammation)...
Leukoencephalomalacia Outbreak in Horses due to Consumption of Contaminated Hay.
Journal of veterinary internal medicine    October 15, 2016   Volume 30, Issue 6 1879-1881 doi: 10.1111/jvim.14588
Vendruscolo CP, Frias NC, de Carvalho CB, de Sá LR, Belli CB, Baccarin RY.No abstract available
Transcriptome profiling of equine vitamin E deficient neuroaxonal dystrophy identifies upregulation of liver X receptor target genes.
Free radical biology & medicine    October 15, 2016   Volume 101 261-271 doi: 10.1016/j.freeradbiomed.2016.10.009
Finno CJ, Bordbari MH, Valberg SJ, Lee D, Herron J, Hines K, Monsour T, Scott E, Bannasch DL, Mickelson J, Xu L.Specific spontaneous heritable neurodegenerative diseases have been associated with lower serum and cerebrospinal fluid α-tocopherol (α-TOH) concentrations. Equine neuroaxonal dystrophy (eNAD) has similar histologic lesions to human ataxia with vitamin E deficiency caused by mutations in the α-TOH transfer protein gene (TTPA). Mutations in TTPA are not present with eNAD and the molecular basis remains unknown. Given the neuropathologic phenotypic similarity of the conditions, we assessed the molecular basis of eNAD by global transcriptome sequencing of the cervical spinal cord. Differential...
Nitrite coordination in myoglobin.
Journal of inorganic biochemistry    October 14, 2016   Volume 166 49-54 doi: 10.1016/j.jinorgbio.2016.10.002
Ioannou A, Lambrou A, Daskalakis V, Pinakoulaki E.The coordination of nitrite in myoglobin (Mb) has been characterized by resonance Raman spectroscopy and the frequencies of the nitrite bound to the heme Fe as well to the 2-vinyl have been computed by density functional theory (DFT) calculations. The DFT Natural Bond Orbital (NBO) analysis and the extensive isotope-labeling in the resonance Raman experiments indicate that NO (O1NO2) is bound to the heme Fe via O1. Based on the vibrational characterization of the reversible transition between low and high spin FeONO/2-nitrovinyl species, we suggest that the key step that triggers the spin-chan...
Degree of corneal anesthesia after topical application of 0.4% oxybuprocaine ophthalmic solution in normal equids.
Canadian journal of veterinary research = Revue canadienne de recherche veterinaire    October 14, 2016   Volume 80, Issue 4 329-334 
Little E, Yvorchuk-St Jean K, Little W, Sithole F, St Jean G.Oxybuprocaine hydrochloride ophthalmic solution has been widely used off-label in horses and donkeys, despite lack of data demonstrating efficacy and safety in these species. The objective of this study was to assess anesthetic efficacy of 0.4% oxybuprocaine hydrochloride ophthalmic solution in horses ( = 5) and donkeys ( = 24) and compare the effects with 0.5% proparacaine hydrochloride ophthalmic solution. The baseline corneal touch threshold (CTT) was measured with a Cochet-Bonnet esthesiometer. Donkeys ( = 12) and horses ( = 5) in group A received sterile ophthalmic solutions 0.4% oxybupro...
Evaluation of adipose-derived stromal vascular fraction from the lateral tailhead, inguinal region, and mesentery of horses.
Canadian journal of veterinary research = Revue canadienne de recherche veterinaire    October 14, 2016   Volume 80, Issue 4 294-301 
Metcalf GL, McClure SR, Hostetter JM, Martinez RF, Wang C.Use of mesenchymal stem cells (MSCs) found in the stromal vascular fraction (SVF) of equine adipose tissue has promising applications for regenerative therapies. The most commonly used source of equine adipose tissue is the subcutaneous tailhead. The objective of this study was to compare 3 adipose depot sites in horses and determine the viability and cellular yield, capillary density, gene expression for selected markers, and colony-forming unit fibroblasts (CFU-Fs) in adipose tissue taken from these sites. Adipose tissue was excised from the area lateral to the tailhead, the inguinal region,...
The Evolutionary Origin and Genetic Makeup of Domestic Horses.
Genetics    October 13, 2016   Volume 204, Issue 2 423-434 doi: 10.1534/genetics.116.194860
Librado P, Fages A, Gaunitz C, Leonardi M, Wagner S, Khan N, Hanghøj K, Alquraishi SA, Alfarhan AH, Al-Rasheid KA, Der Sarkissian C, Schubert M....The horse was domesticated only 5.5 KYA, thousands of years after dogs, cattle, pigs, sheep, and goats. The horse nonetheless represents the domestic animal that most impacted human history; providing us with rapid transportation, which has considerably changed the speed and magnitude of the circulation of goods and people, as well as their cultures and diseases. By revolutionizing warfare and agriculture, horses also deeply influenced the politico-economic trajectory of human societies. Reciprocally, human activities have circled back on the recent evolution of the horse, by creating hundreds...
Efficacy of a Feed Dispenser for Horses in Decreasing Cribbing Behaviour.
Veterinary medicine international    October 13, 2016   Volume 2016 4698602 doi: 10.1155/2016/4698602
Mazzola S, Palestrini C, Cannas S, Fè E, Bagnato GL, Vigo D, Frank D, Minero M.Cribbing is an oral stereotypy, tends to develop in captive animals as a means to cope with stress, and may be indicative of reduced welfare. Highly energetic diets ingested in a short time are one of the most relevant risk factors for the development of cribbing. The aim of this study was to verify whether feeding cribbing horses through a dispenser that delivers small quantities of concentrate when activated by the animal decreases cribbing behaviour, modifies feeding behaviour, or induces frustration. Ten horses (mean age 14 y), balanced for sex, breed, and size (mean height 162 cm), we...
Improved radiological diagnosis of palmar osteochondral disease in the Thoroughbred racehorse.
Equine veterinary journal    October 13, 2016   Volume 49, Issue 4 454-460 doi: 10.1111/evj.12636
Davis AM, Fan X, Shen L, Robinson P, Riggs CM.Palmar osteochondral disease (POD) is common in the Thoroughbred racehorse yet difficult to diagnose by radiography alone. Objective: To improve the sensitivity and specificity for diagnosing POD from radiographs. Methods: Prospective, longitudinal study. Methods: Radiographs in nine different projections were made of metacarpophalangeal joints (MCPJ) of 50 Thoroughbreds. Post-mortem, MCPJs were dissected and gross pathology was scored. Three experienced Thoroughbred clinicians read each radiograph and recorded their findings. Another clinician reviewed each radiograph alongside the related gr...
The preventive effects of two nutraceuticals on experimentally induced acute synovitis.
Equine veterinary journal    October 13, 2016   Volume 49, Issue 4 532-538 doi: 10.1111/evj.12629
van de Water E, Oosterlinck M, Dumoulin M, Korthagen NM, van Weeren PR, van den Broek J, Everts H, Pille F, van Doorn DA.Nutraceuticals are often used in the management of equine osteoarthritis, but scientific evidence of their efficacy is lacking. Objective: To study the preventive effects of two new nutraceuticals after the experimental induction of synovitis in comparison with positive and negative control treatments. Methods: Blinded, controlled, randomised experiment. Methods: Twenty-four healthy Standardbred horses were randomly allocated to supplement AT (multi-ingredient, 28 days), supplement HP (collagen hydrolysate, 60 days), meloxicam (4 days) or placebo (60 days). Synovitis was induced in the right i...
Risk factors in equine transport-related health problems: A survey of the Australian equine industry.
Equine veterinary journal    October 13, 2016   Volume 49, Issue 4 507-511 doi: 10.1111/evj.12631
Padalino B, Raidal SL, Hall E, Knight P, Celi P, Jeffcott L, Muscatello G.Transportation can affect equine health and is a potential source of economic loss to the industry. Objective: To identify journey (duration, vehicle, commercial or noncommercial) and horse (sex, age, breed, use, amateur or professional status) characteristics associated with the development of transport-related health problems in horses. Methods: Cross-sectional online survey. Methods: An online survey was conducted targeting amateur and professional participants in the Australian equine industry; eligible respondents were required to organise horse movements at least monthly. Respondents pro...
Intranasal Location and Immunohistochemical Characterization of the Equine Olfactory Epithelium.
Frontiers in neuroanatomy    October 13, 2016   Volume 10 97 doi: 10.3389/fnana.2016.00097
Kupke A, Wenisch S, Failing K, Herden C.The olfactory epithelium (OE) is the only body site where neurons contact directly the environment and are therefore exposed to a broad variation of substances and insults. It can serve as portal of entry for neurotropic viruses which spread via the olfactory pathway to the central nervous system. For horses, it has been proposed and concluded mainly from rodent studies that different viruses, e.g., Borna disease virus, equine herpesvirus 1 (EHV-1), hendra virus, influenza virus, rabies virus, vesicular stomatitis virus can use this route. However, little is yet known about cytoarchitecture, p...
Factors associated with survival of horses following relaparotomy.
Equine veterinary journal    October 13, 2016   Volume 49, Issue 4 448-453 doi: 10.1111/evj.12635
Findley JA, Salem S, Burgess R, Archer DC.Relaparotomy may be required to investigate and manage complications that occur following surgical management of colic. Objective: To report factors associated with survival following relaparotomy. Methods: Retrospective cohort study. Methods: Records of horses that had undergone exploratory laparotomy for treatment of colic over a 10-year period (2002-2012) and had undergone relaparotomy <8 weeks following the initial surgery were reviewed. Descriptive data were generated and association with survival time was modelled using Cox proportional hazards models. Results: Relaparotomy was perfor...
Owner reported diseases of working equids in central Ethiopia.
Equine veterinary journal    October 13, 2016   Volume 49, Issue 4 501-506 doi: 10.1111/evj.12633
Stringer AP, Christley RM, Bell CE, Gebreab F, Tefera G, Reed K, Trawford A, Pinchbeck GL.Working horses, donkeys and mules suffer from numerous diseases and clinical problems. However, there is little information on what owners perceive as important health concerns in their working animals. Objective: To identify and prioritise with owners the diseases and other health concerns in working equids in central Ethiopia using participatory methodologies. Methods: Participatory situation analysis (PSA). Methods: The study was conducted with carthorse- and donkey-owners in 16 sites in central Ethiopia. Multiple participatory methodologies were utilised, including ranking, matrices and fo...
Transnasal, Endoscopically Guided Skull-Based Surgery by Pharyngotomy for Mass Removal from the Sphenopalatine Sinus in a Horse.
Veterinary surgery : VS    October 12, 2016   Volume 45, Issue 8 1108-1117 doi: 10.1111/vsu.12573
Radcliffe RM, Messiaen Y, Irby NL, Divers TJ, Dewey CW, Mitchell KJ, Schnabel LV, Bezuidenhout AJ, Scrivani PV, Ducharme NG.To report a transnasal, endoscopically guided ventral surgical approach for accessing the cranial and caudal segments of the sphenopalatine sinus for mass removal in a horse. Methods: Case report. Methods: Adult horse with acute onset blindness referable to a soft tissue mass within the sphenopalatine sinus. Methods: A 7-year-old Warmblood gelding presented with a history of running into a fence and falling. No neurologic signs were identified at initial examination but acute blindness was noted 3 weeks later. On computed tomography (CT) the sphenopalatine sinus was filled with a large homogen...
Are Eyes a Mirror of the Soul? What Eye Wrinkles Reveal about a Horse’s Emotional State.
PloS one    October 12, 2016   Volume 11, Issue 10 e0164017 doi: 10.1371/journal.pone.0164017
Hintze S, Smith S, Patt A, Bachmann I, Würbel H.Finding valid indicators of emotional states is one of the biggest challenges in animal welfare science. Here, we investigated in horses whether variation in the expression of eye wrinkles caused by contraction of the inner eyebrow raiser reflects emotional valence. By confronting horses with positive and negative conditions, we aimed to induce positive and negative emotional states, hypothesising that positive emotions would reduce whereas negative emotions would increase eye wrinkle expression. Sixteen horses were individually exposed in a balanced order to two positive (grooming, food antic...
In Vitro and In Vivo Development of Horse Cloned Embryos Generated with iPSCs, Mesenchymal Stromal Cells and Fetal or Adult Fibroblasts as Nuclear Donors.
PloS one    October 12, 2016   Volume 11, Issue 10 e0164049 doi: 10.1371/journal.pone.0164049
Olivera R, Moro LN, Jordan R, Luzzani C, Miriuka S, Radrizzani M, Donadeu FX, Vichera G.The demand for equine cloning as a tool to preserve high genetic value is growing worldwide; however, nuclear transfer efficiency is still very low. To address this issue, we first evaluated the effects of time from cell fusion to activation (<1h, n = 1261; 1-2h, n = 1773; 2-3h, n = 1647) on in vitro and in vivo development of equine embryos generated by cloning. Then, we evaluated the effects of using different nuclear donor cell types in two successive experiments: I) induced pluripotent stem cells (iPSCs) vs. adult fibroblasts (AF) fused to ooplasts injected with the pluripotency-inducin...
Effects of Firocoxib, Flunixin Meglumine, and Phenylbutazone on Platelet Function and Thromboxane Synthesis in Healthy Horses.
Veterinary surgery : VS    October 12, 2016   Volume 45, Issue 8 1087-1094 doi: 10.1111/vsu.12567
Burkett BN, Thomason JM, Hurdle HM, Wills RW, Fontenot RL.Determine the effects of nonsteroidal anti-inflammatory drugs (NSAID) on platelet function and thromboxane synthesis immediately after drug administration and following 5 days of NSAID administration in healthy horses. Methods: Randomized cross-over study. Methods: Healthy adult horses (n=9; 6 geldings and 3 mares). Methods: Horses received either flunixin meglumine (1.1 mg/kg IV every 12 hours), phenylbutazone (2.2 mg/kg IV every 12 hours), or firocoxib (loading dose of 0.27 mg/kg IV on day 1, then 0.09 mg/kg IV every 24 hours for 4 days) for a total of 5 days. Blood samples were collected pr...
Microvesicle-mediated Wnt/β-Catenin Signaling Promotes Interspecies Mammary Stem/Progenitor Cell Growth.
The Journal of biological chemistry    October 12, 2016   Volume 291, Issue 47 24390-24405 doi: 10.1074/jbc.M116.726117
Bussche L, Rauner G, Antonyak M, Syracuse B, McDowell M, Brown AMC, Cerione RA, Van de Walle GR.Signaling mechanisms that regulate mammary stem/progenitor cell (MaSC) self-renewal are essential for developmental changes that occur in the mammary gland during pregnancy, lactation, and involution. We observed that equine MaSCs (eMaSCs) maintain their growth potential in culture for an indefinite period, whereas canine MaSCs (cMaSCs) lose their growth potential in long term cultures. We then used this system to investigate the role of microvesicles (MVs) in promoting self-renewal properties. We found that Wnt3a and Wnt1 were expressed at higher levels in MVs isolated from eMaSCs compared wi...
Influence of Plasmid Type on the Replication of Rhodococcus equi in Host Macrophages.
mSphere    October 12, 2016   Volume 1, Issue 5 e00186-16 doi: 10.1128/mSphere.00186-16
Willingham-Lane JM, Berghaus LJ, Giguère S, Hondalus MK.The soil-dwelling, saprophytic actinomycete is a multihost, facultative intracellular pathogen of macrophages. When inhaled by susceptible foals, it causes severe bronchopneumonia. It is also a pathogen of pigs, which may develop submaxillary lymphadenitis upon exposure. isolates obtained from foals and pigs possess conjugative plasmids housing a pathogenicity island (PAI) containing a novel family of genes of unknown function called the virulence-associated protein or family. The PAI regions of the equine and swine plasmids differ in gene composition, with equine isolates possessing six ...
Comparison of psyllium feeding at home and nasogastric intubation of psyllium and magnesium sulfate in the hospital as a treatment for naturally occurring colonic sand (geosediment) accumulations in horses: a retrospective study.
Acta veterinaria Scandinavica    October 12, 2016   Volume 58, Issue 1 73 doi: 10.1186/s13028-016-0254-z
Kaikkonen R, Niinistö K, Lindholm T, Raekallio M.Ingestion of geosediment (further referred as sand) may cause weight loss, diarrhea and acute or recurrent colic in horses. Our aim was to compare the efficacy of three treatment protocols in clearing colonic sand accumulations in clinical patients. This retrospective clinical study consisted of 1097 horses and ponies, which were radiographed for the presence of colonic sand. Horses included to the study (n = 246) were displaying areas of sand in the radiographs of ≥75 cm2 and were treated medically monitoring the response with radiographs. The horses were assigned into three groups base...
The Role of the Equine Herpesvirus Type 1 (EHV-1) US3-Encoded Protein Kinase in Actin Reorganization and Nuclear Egress.
Viruses    October 12, 2016   Volume 8, Issue 10 275 doi: 10.3390/v8100275
Proft A, Spiesschaert B, Izume S, Taferner S, Lehmann MJ, Azab W.The serine-threonine protein kinase encoded by gene (pUS3) of alphaherpesviruses was shown to modulate actin reorganization, cell-to-cell spread, and virus egress in a number of virus species. However, the role of the US3 orthologues of equine herpesvirus type 1 and 4 (EHV-1 and EHV-4) has not yet been studied. Here, we show that is not essential for virus replication in vitro. However, growth rates and plaque diameters of a -deleted EHV-1 and a mutant in which the catalytic active site was destroyed were significantly reduced when compared with parental and revertant viruses or a virus in w...