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Topic:Veterinary Medicine

Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
A cross-sectional study of Leishmania spp. in draft horses from the Distrito Federal, Brazil: Seroprevalence, spatial distribution, and associated factors.
Preventive veterinary medicine    August 17, 2021   Volume 195 105467 doi: 10.1016/j.prevetmed.2021.105467
Biral NV, Azevedo Santos H, Senne NA, Paulino PG, Camilo TA, Tassinari WS, Silva VL, Santos FN, Angelo IDC.Equine leishmaniasis is a neglected tropical disease caused by the protozoan of the Leishmania genus, and it has been reported in several countries around the world, especially Brazil. Therefore, the present investigation aims to conduct a cross-sectional study to determine the prevalence, spatial distribution, and associated factors with seropositivity for Leishmania spp. in draft horses from the Distrito Federal, Brazil. The serological survey was conducted on 411 animals, employing the Indirect Immunofluorescence Test (IFA) and Enzyme-Linked Immunosorbent Assay (ELISA). The Kappa (κ) and g...
Bile Acids, Direct Bilirubin and Gamma-glutamyltransferase as Prognostic Indicators for Horses with Liver Disease in the Eastern United States: 82 Cases (1997-2019).
Journal of equine veterinary science    August 16, 2021   Volume 105 103729 doi: 10.1016/j.jevs.2021.103729
Delvescovo B, Tomlinson J, DeNotta S, Hodge E, Bookbinder L, Mohammed HO, Divers TJ.Serum biochemistry results and presence of fibrosis on liver biopsies are frequently used as prognostic indicators in horses with liver dysfunction. The objective of this retrospective multicenter study was to determine if the magnitude of abnormal liver specific biochemical tests such as bile acids (BA), direct bilirubin and gamma-glutamyltransferase (GGT), or the presence of fibrosis reported on liver biopsies was associated with prognosis in horses with liver dysfunction. Eighty-two horses older than one year, examined at four referral hospitals in the eastern United States, with BA values ...
Thermal features, ambient temperature and hair coat lengths: Limitations of infrared imaging in pregnant primitive breed mares within a year.
Reproduction in domestic animals = Zuchthygiene    August 16, 2021   Volume 56, Issue 10 1315-1328 doi: 10.1111/rda.13994
Maśko M, Witkowska-Piłaszewicz O, Jasiński T, Domino M.Infrared thermography is a non-invasive technique which allows to distinguish between pregnant and non-pregnant animals. Detecting accurate body surface temperatures can be challenging due to external factors altering thermograph measurements. This study aimed to determine the associations between the ambient temperature, the hair coat features and the temperatures of mares' abdomens. It compared pregnant and non-pregnant mares throughout 11 months. The research was carried out on 40 Konik Polski mares, which were divided into pregnant and non-pregnant groups. The temperature (Tmax, maximal; ...
Retrobulbar lidocaine injection via the supraorbital fossa is safe in adult horses but produces regionally variable periocular anaesthesia.
Equine veterinary journal    August 16, 2021   doi: 10.1111/evj.13496
Yang VY, Eaton JS, Harmelink K, Hetzel SJ, Sanchez A, Lund JR, Smith LJ.Injection techniques for retrobulbar anaesthesia are published in horses, but neither safety nor anaesthetic efficacy and duration have been evaluated objectively in vivo. Objective: To characterise the safety and efficacy of one published technique for retrobulbar anaesthesia. Methods: Randomised, controlled descriptive experiment. Methods: Unilateral retrobulbar injection with 10 mL lidocaine (2%) was performed in eight sedated adult mares. Contralateral eyes served as untreated controls. Neurophthalmic parameters, intraocular pressure (IOP), and corneal and periocular sensation were measur...
Summer Sores Secondary to a Hoof Crack in an Andalusian Stallion.
Pathogens (Basel, Switzerland)    August 16, 2021   Volume 10, Issue 8 doi: 10.3390/pathogens10081038
Palozzo A, Traversa D, Marruchella G, Celani G, Morelli S, Petrizzi L.Cutaneous habronemosis in horses is caused by larvae of the spirurid nematodes Habronema microstoma and Habronema muscae. These lesions, also known as "summer sores'', are often severe and disfiguring. Although Habronema-caused lesions at the coronary grooves have been described, cases of hoof cracks with secondary summer sores have never been reported. The present case describes clinic-pathological and surgical features of a quarter crack case complicated by cutaneous habronemosis at the dermal layers. A 15-year-old, Andalusian stallion was referred to the Veterinary Teaching Hospital of the ...
Two successful embryo transfers of mini-donkey embryos in Brazilian Northeastern jennies using an alternative method: Case report.
Reproduction in domestic animals = Zuchthygiene    August 15, 2021   Volume 56, Issue 11 1470-1474 doi: 10.1111/rda.14000
Rodrigues LT, Segabinazzi LG, Oliveira SN, Frasson M, Papa FO.Pregnancy rates after embryo transfer (ET) are disappointing in donkey species. This study aims to report two successful ET of mini-donkey embryos using Brazilian Northeastern jennies as recipients. Eighteen embryo flushes were performed 9 days post-ovulation in two non-pregnant mini-donkeys jennies (11 and 7 cycles per jenny). Eleven embryos (61%, 11/18) were collected and transferred to Brazilian Northeastern jennies 4-6 days post-ovulation by conventional (n = 6) or an alternative (n = 5) technique. The alternative method consisted of inserting a Polansky equine vaginal speculum smear...
Induction of parturition in horses – from physiological pathways to clinical applications.
Domestic animal endocrinology    August 15, 2021   Volume 78 106670 doi: 10.1016/j.domaniend.2021.106670
Nagel C, Aurich C.Based on the marked variability in physiological equine gestation length, induction of foaling in mares often results in the birth of dysmature foals. Precise prediction of preparedness of the mare for foaling is thus essential. Treatment with glucocorticoids mimics the fetal signal that initiates birth. Repeated daily dexamethasone treatment in late gestation results in birth of mature foals but the time from initiation of treatment to foaling is highly variable and complications such as dystocia have been reported. Contrary to most expectations, treatment of prepartum mares with progestogens...
New Parvoviruses and Picornavirus in Tissues and Feces of Foals with Interstitial Pneumonia.
Viruses    August 14, 2021   Volume 13, Issue 8 1612 doi: 10.3390/v13081612
Altan E, Hui A, Li Y, Pesavento P, Asín J, Crossley B, Deng X, Uzal FA, Delwart E.Six foals with interstitial pneumonia of undetermined etiology from Southern California were analyzed by viral metagenomics. Spleen, lung, and colon content samples obtained during necropsy from each animal were pooled, and nucleic acids from virus-like particles enriched for deep sequencing. The recently described equine copiparvovirus named eqcopivirus, as well as three previously uncharacterized viruses, were identified. The complete ORFs genomes of two closely related protoparvoviruses, and of a bocaparvovirus, plus the partial genome of a picornavirus were assembled. The parvoviruses were...
Equine attachment site preferences and seasonality of common North American ticks: Amblyomma americanum, Dermacentor albipictus, and Ixodes scapularis.
Parasites & vectors    August 14, 2021   Volume 14, Issue 1 404 doi: 10.1186/s13071-021-04927-8
Sundstrom KD, Lineberry MW, Grant AN, Duncan KT, Ientile MM, Little SE.Ticks are common on horses, but recent publications characterizing equine tick infestations in North America are lacking. Methods: To further understand attachment site preferences of common ticks of horses, and to document the seasonality of equine tick infestation in northeastern Oklahoma, horses from eight farms were evaluated twice a month over a 1-year period. Each horse was systematically inspected beginning at the head and moving caudally to the tail. Attachment sites of ticks were recorded and all ticks collected were identified to species and stage. Results: Horses (26 males and 62 fe...
Generation of equine enteroids and enteroid-derived 2D monolayers that are responsive to microbial mimics.
Veterinary research    August 14, 2021   Volume 52, Issue 1 108 doi: 10.1186/s13567-021-00976-0
Hellman S.Enteroid cultures are three-dimensional in vitro models that reflect the cellular composition and architecture of the small intestine. One limitation with the enteroid conformation is the enclosed lumen, making it difficult to expose the apical surface of the epithelium to experimental treatments. The present study was therefore conducted to generate cultures of equine enteroids and to develop methods for culture of enteroid-derived cells on a two-dimensional plane, enabling easy access to the apical surface of the epithelium. Equine enteroids were established from small intestinal crypts with...
Microbial Variability of Commercial Equine Probiotics.
Journal of equine veterinary science    August 14, 2021   Volume 106 103728 doi: 10.1016/j.jevs.2021.103728
Berreta A, Burbick CR, Alexander T, Kogan C, Kopper JJ.Probiotics are defined as live microorganisms that confer a health benefit to the host when administered in adequate amounts, therefore the presence of viable microorganisms is essential. Previous studies reported inconsistencies when comparing contents of probiotics marketed for use in animals with label claims. However, to the author's knowledge the variability of the same product between different lots has yet to be evaluated. The objective of this observational study was to evaluate the content and inter-lot variability of commercial equine probiotic products using culture dependent and in...
Molecular detection and phylogenetic characterization of Theileria equi in horses (Equus caballus) from a peri-urban area of Argentina.
Ticks and tick-borne diseases    August 13, 2021   Volume 12, Issue 6 101810 doi: 10.1016/j.ttbdis.2021.101810
Sebastian PS, Benitez-Ibalo AP, Flores FS, Debárbora VN, Martinez EI, Thompson CS, Mangold AJ.To investigate the presence of Theileria equi in an endemic area of equine piroplasmosis 42 horses (Equus caballus) from Corrientes City, Argentina were sampled. Eighty-one percent (34 blood samples) of the analyzed horses were tested positive to the presence of piroplasmid 18S rDNA. All these samples could be identified as T. equi by amplifying the specific EMA-1 (merozoite antigen 1) gene of this species. Phylogenetic analysis of an obtained 18S rDNA complete sequence from one strain resulted in the identification of this sample as T. equi sensu stricto (genotype A). This study presents the ...
Humoral Immune Response Evaluation in Horses Vaccinated with Recombinant Clostridium perfringens Toxoids Alpha and Beta for 12 Months.
Toxins    August 13, 2021   Volume 13, Issue 8 doi: 10.3390/toxins13080566
Freitas NFQR, Otaka DY, Galvão CC, de Almeida DM, Ferreira MRA, Moreira Júnior C, Hidalgo MMMH, Conceição FR, Salvarani FM.In horses, Clostridium perfringens is associated with acute and fatal enterocolitis, which is caused by a beta toxin (CPB), and myonecrosis, which is caused by an alpha toxin (CPA). Although the most effective way to prevent these diseases is through vaccination, specific clostridial vaccines for horses against C. perfringens are not widely available. The aim of this study was to pioneer the immunization of horses with three different concentrations (100, 200 and 400 µg) of C. perfringens recombinant alpha (rCPA) and beta (rCPB) proteins, as well as to evaluate the humoral immune response ove...
Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies.
Veterinary anaesthesia and analgesia    August 13, 2021   Volume 48, Issue 6 930-934 doi: 10.1016/j.vaa.2021.05.005
Calero Rodriguez A, de Grauw JC, van Loon JPAM.To determine the effect of fraction of inspired oxygen (FiO) on intrapulmonary shunt fraction as measured by F-shunt in ponies during isoflurane anaesthesia. Methods: Prospective, randomized clinical study. Methods: A group of 23 adult Shetland ponies undergoing a total of 32 anaesthetic procedures. Methods: Ponies were premedicated intravenously (IV) with detomidine (0.01 mg kg) and either morphine (0.1 mg kg) or butorphanol (0.02 mg kg). Anaesthesia was induced with ketamine (2.2 mg kg) and midazolam (0.07 mg kg) administered IV. Ponies were randomly allocated to maintenance of anaesthesia w...
Reproductive patterns and follicular waves in postpartum lactating versus non-postpartum cycling mares.
Journal of equine veterinary science    August 13, 2021   Volume 107 103732 doi: 10.1016/j.jevs.2021.103732
Gastal EL, Pastorello M, Godoi DB, Gastal MO.This comparative study between postpartum lactating (PP Lactating) and non-postpartum cycling (N-PP Cycling) mares aimed to characterize reproductive patterns, types and frequencies of follicular waves, corpus luteum and endometrial echotexture dynamics, and the influence of season and body condition. Mares from each group were paired considering the day of parturition of a PP Lactating mare. The partum-ovulation interval (POI) and the postpartum interovulatory interval (PPIOI) were evaluated for PP Lactating mares, and 2 IOIs were evaluated for N-PP Cycling mares. The following observations w...
Uterine Involution of Mares Supplemented with Dietary Algae-Derived Omega-3 Fatty Acids During the Peripartum Period.
Journal of equine veterinary science    August 13, 2021   Volume 106 103733 doi: 10.1016/j.jevs.2021.103733
Ferreira JRM, Villela SB, Bianconi C, Ormieres M, de Melo GD, Pugliesi G, Gobesso AAO.Different approaches have been used to improve conception rates at foal heat. Omega-3 fatty acids family and derivatives have improved reproductive efficiency in ruminants, but literature lacks studies evaluating these components on equines. The objective of this study was to evaluate effects of mare dietary supplementation with microalgae rich in docosahexaenoic acid (DHA) during peripartum on follicular dynamics and uterine involution in early post-partum. Eighteen pregnant mares, no particular breed, 410 ± 39.5 kg body weight (BW), and 7.83 ± 2.01 yr old were used. Mares were randomly ass...
Total Carbon Dioxide in Adult Standardbred and Thoroughbred Horses.
Journal of equine veterinary science    August 12, 2021   Volume 106 103730 doi: 10.1016/j.jevs.2021.103730
Lindinger MI.The TCO2 (total carbon dioxide) test is performed on the blood of racehorses as a means of combatting the practice of administering alkalizing agents for the purpose of enhancing performance. The purposes of this review are to present an overview of the factors contributing to TCO2 and to review the literature regarding TCO2 in adult Standardbred and Thoroughbred horses to demonstrate the range of variability of TCO2 in horses. Most of the research published on the topic of TCO2 or bicarbonate measurement in racehorses was accessed and reviewed. PubMed and Google Scholar were the primary sear...
Magnetic Resonance Imaging Findings of the Proximal Metacarpal Region in Warmblood Horses: 36 Lame and 26 Control Limbs (2015-2021).
Frontiers in veterinary science    August 12, 2021   Volume 8 714423 doi: 10.3389/fvets.2021.714423
van Veggel E, Selberg K, van der Velde-Hoogelander B, Bolas N, Vanderperren K, Bergman HJ. This study aims to evaluate the distribution and severity of bone and soft tissue lesions in the proximal metacarpal region of warmblood horses in lame and control groups. Correlation between lesions and ability to return to work was evaluated in the lame group. This restrospective analysis evaluated 62 horses with MRI examination of the proximal metacarpal region between Sept 2015 and Feb 2021. There were 36 lame limbs and 26 control limbs. The control group included seven contralateral limbs. Proximal suspensory ligament (PSL) size was not different between the lame and control groups. Hy...
Use of Polyamide (Nylon) Cable Ties for Vascular Ligation of Healthy Equine Jejunal Mesentery.
Frontiers in veterinary science    August 12, 2021   Volume 8 639424 doi: 10.3389/fvets.2021.639424
Hurcombe SD, Roessner HA, Klein CE, Engiles JB, Hopster K.Jejunal vascular ligation is an essential step in performing jejunojejunostomy. Hand sewn ligation is typically used and can increase operative time with long sections of bowel to be removed. Nylon cable ties (NCT) have been used for vascular ligation in horses but are yet to be investigated for application on the mesenteric vasculature of the gastrointestinal tract. Our objective was to evaluate the efficacy and short-term safety of NCT jejunal mesenteric vessel ligation in healthy horses. Eight healthy adult horses underwent midline celiotomy. A segment of jejunal mesentery was identified (...
Split Cord Malformation in a Thoroughbred Horse.
Journal of comparative pathology    August 12, 2021   Volume 187 68-74 doi: 10.1016/j.jcpa.2021.07.003
De Jonge B, Dufourni A, Oosterlinck M, Chiers K.We report a 9-year-old Thoroughbred gelding that had sudden onset lameness of the right forelimb with episodes of lateral decubitus and generalized pain after completion of a normal training session. The clinical signs subsequently became less pronounced with only mild right forelimb lameness. However, after further orthopaedic examination, it developed severe, acute ataxia and paraplegia, the Schiff-Sherrington phenomenon and risus sardonicus. At necropsy, a partial duplication of the cervical spinal cord was identified, consistent with split spinal cord malformation type II or diplomyelia. H...
Cooled storage of semen from livestock animals (part I): boar, bull, and stallion.
Animal reproduction science    August 12, 2021   Volume 246 106822 doi: 10.1016/j.anireprosci.2021.106822
Wiebke M, Hensel B, Nitsche-Melkus E, Jung M, Schulze M.This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques for cooled storage of semen from livestock animals. The first part describes the current state of the art of liquid semen preservation in boars, bulls, and stallions, including the diluents, use of additives, processing, temperature, and cooling of semen. The species-specific physiology and varying extents of cold shock sensitivity are taken into consideration. In addition, factors influencing the quality of cooled-stored semen are discussed. Methods, trends, and the most recent a...
Detection of pathogens in blood or feces of adult horses with enteric disease and association with outcome of colitis.
Journal of veterinary internal medicine    August 12, 2021   Volume 35, Issue 5 2465-2472 doi: 10.1111/jvim.16238
Kopper JJ, Willette JA, Kogan CJ, Seguin A, Bolin SR, Schott HC.Rates of detecting ≥1 potential enteric pathogens (PEP) or toxins (PEP-T) in feces, blood, or both of horses ≥6 months of age with enteric disease and impact of multiple detections on outcome of horses with colitis has not been reported. Objective: To determine detection rates of PEP/PEP-T in feces, blood, or both of horses with enteric disease and effect of detecting multiple agents on outcome of horses with colitis. Methods: Thirty-seven hundred fifty-three fecal samples submitted to IDEXX Laboratories and 239 fecal and blood samples submitted to Michigan State University's Veterinary D...
Equine Parvovirus-Hepatitis Screening in Horses and Donkeys with Histopathologic Liver Abnormalities.
Viruses    August 12, 2021   Volume 13, Issue 8 doi: 10.3390/v13081599
Zehetner V, Cavalleri JV, Klang A, Hofer M, Preining I, Steinborn R, Ramsauer AS.There is strong evidence that equine parvovirus-hepatitis (EqPV-H) is associated with the onset of Theiler's disease, an acute hepatic necrosis, in horses. However, the impact of this virus on other hepatopathies remains unknown. The objective of this retrospective study was to evaluate the prevalence and quantify the viral loads of EqPV-H in formalin-fixed, paraffin-embedded equine and donkey livers with various histopathologic abnormalities. The pathologies included cirrhosis, circulatory disorders of the liver, toxic and metabolic hepatic diseases as well as neoplastic and inflammatory dise...
Early Evidence of the Economic Effects of COVID-19 on the Horse Show Industry in 2020.
Journal of equine veterinary science    August 12, 2021   Volume 106 103734 doi: 10.1016/j.jevs.2021.103734
Huseman C, Walker N, McCorkle DA, Hanselka D, Cater M, Zoller J.The COVID-19 pandemic affected the economic status of all sectors of the global economy including the horse show industry. Reporting the impact of COVID-19 on in-person horse shows and an early assessment of its impact on the economy was the objective of this study. A Qualtrics survey instrument was disseminated to horse show participants through social media pages and email (n = 251). A majority of respondents were females (95.6%) representing a cross-section of the United States (84.0%). Participants reported planning to attend an average of 9.7 (SD = 7.15) in-person horse shows in 2020...
Qualitative and quantitative analyses of polysomnographic measurements in foals.
Scientific reports    August 11, 2021   Volume 11, Issue 1 16288 doi: 10.1038/s41598-021-95770-5
Zanker A, Wöhr AC, Reese S, Erhard M.Veterinary and human medicine are still seeking a conclusive explanation of the function of sleep, including the change in sleep behaviour over the course of an individual's lifetime. In human medicine, sleep disorders and abnormalities in the electroencephalogram are used for prognostic statements, therapeutic means and diagnoses. To facilitate such use in foal medicine, we monitored 10 foals polysomnographically for 48 h. Via 10 attached cup electrodes, brain waves were recorded by electroencephalography, eye movements by electrooculography and muscle activity by electromyography. Wireless ...
Horse Behavior towards Familiar and Unfamiliar Humans: Implications for Equine-Assisted Services.
Animals : an open access journal from MDPI    August 11, 2021   Volume 11, Issue 8 2369 doi: 10.3390/ani11082369
Brubaker L, Schroeder K, Sherwood D, Stroud D, Udell MAR.While human benefits of animal-assisted therapy programs have been documented, relatively little research has been conducted on behavioral factors that predict a successful equine-assisted services (EAS) horse. This study compares the behavior of experienced and non-experienced EAS horses as well as horses selected for future EAS work in a series of sociability and temperament tests. No significant differences were found between experienced and non-experienced horses in the sociability measures or for most of the temperament tests; however, significant differences were found between groups in ...
A study of the shoulder and elbow joints of the donkey (Equus asinus) by gross anatomical dissection, radiography, computed tomography, and intra-articular injection.
Morphologie : bulletin de l\'Association des anatomistes    August 11, 2021   Volume 106, Issue 354 177-187 doi: 10.1016/j.morpho.2021.07.002
Alsafy MAM, Elbakary RMA, Bassuoni NF.Joint diseases often represent the major part of equine clinician's caseloads. The current study aimed to document the normal anatomy of the donkey shoulder and elbow joints using computed tomography, cadaver sections, and radiography. Seven adult donkeys were used in this study. The current study proved there were no pouches of the donkey shoulder joint. Communication between the joint capsule and bicipital bursa was observed only in two limbs of four used in the present work. The joint was without pericapsular ligaments. The glenohumeral ligament was identified by the thickening of the artic...
West Nile Virus in the State of Ceará, Northeast Brazil.
Microorganisms    August 10, 2021   Volume 9, Issue 8 1699 doi: 10.3390/microorganisms9081699
Löwen Levy Chalhoub F, Maia de Queiroz-Júnior E, Holanda Duarte B, Eielson Pinheiro de Sá M, Cerqueira Lima P, Carneiro de Oliveira A....In June 2019, a horse with neurological disorder was diagnosed with West Nile virus (WNV) in Boa Viagem, a municipality in the state of Ceará, northeast Brazil. A multi-institutional task force coordinated by the Brazilian Ministry of Health was deployed to the area for case investigation. A total of 513 biological samples from 78 humans, 157 domestic animals and 278 free-ranging wild birds, as well as 853 adult mosquitoes of 22 species were tested for WNV by highly specific serological and/or molecular tests. No active circulation of WNV was detected in vertebrates or mosquitoes by molecular...
Horses with sustained attention follow the pointing of a human who knows where food is hidden.
Scientific reports    August 10, 2021   Volume 11, Issue 1 16184 doi: 10.1038/s41598-021-95727-8
Ringhofer M, Trösch M, Lansade L, Yamamoto S.When interacting with humans, domesticated species may respond to communicative gestures, such as pointing. However, it is currently unknown, except for in dogs, if species comprehend the communicative nature of such cues. Here, we investigated whether horses could follow the pointing of a human informant by evaluating the credibility of the information about the food-hiding place provided by the pointing of two informants. Using an object-choice task, we manipulated the attentional state of the two informants during food-hiding events and differentiated their knowledge about the location of t...
Analysis on the relationship between winter precipitation and the annual variation of horse stomach fly community in arid desert steppe, Northwest China (2007-2019).
Integrative zoology    August 10, 2021   Volume 17, Issue 1 128-138 doi: 10.1111/1749-4877.12578
Huang H, Zhang K, Zhang B, Liu S, Chu H, Qi Y, Zhang D, Li K.Gasterophilus spp. have been found to be widespread in reintroduced Przewalski's horses in the Kalamaili Nature Reserve (Northwest China). However, data on the annual variation in Gasterophilus infections are lacking. To analyze the epidemiological features and determine the cause of the annual variation in Gasterophilus infections, we treated 110 Przewalski's horses with ivermectin and collected Gasterophilus larvae from fecal samples each winter from 2007 to 2019. All 110 Przewalski's horses studied were found to be infected by Gasterophilus spp., and a total of 141 379 larvae were collected...