The study of diseases in horses encompasses a wide range of conditions affecting equine health, including infectious diseases, metabolic disorders, and genetic abnormalities. These diseases can impact various systems within the horse, such as respiratory, gastrointestinal, and musculoskeletal systems, and can lead to significant health challenges. Research in this area focuses on understanding the pathophysiology, diagnosis, prevention, and treatment of equine diseases. Common diseases studied include equine influenza, equine herpesvirus, and laminitis. This page provides access to peer-reviewed research studies and scholarly articles that explore the etiology, clinical presentation, and management strategies of diseases in horses, contributing to the advancement of equine veterinary medicine.
Ryu SH, Koo HC, Lee YW, Park YH, Lee CW.Infectious upper respiratory disease (IURD) of Thoroughbred racehorses has been a frequent problem (29.6% of incidence) at the Seoul Race Park (Korea). Risk factors for IURD include the season with a high transfer rate (summer and fall), the stabling period (≤ 3 months), and age (2 to 3 years old), suggesting that the movement and new environment may have depressed the immune system of the horses and decreased their ability to respond properly to pathogens. The bacterial strains (n = 98) isolated from IURD horses included Pseudomonas spp., Escherichia coli, Staphylococcus spp., Streptococcus...
Beech J, McFarlane D, Lindborg S, Sojka JE, Boston RC.To compare endogenous ACTH and α-melanocyte-stimulating hormone (α-MSH) concentrations after administration of thyrotropin-releasing hormone (TRH) and to compare ACTH concentrations after TRH administration with those following domperidone administration in healthy horses and horses with pituitary pars intermedia dysfunction (PPID). Methods: Prospective case series. Methods: 69 clinically normal horses and 47 horses with or suspected to have PPID. Methods: ACTH concentrations were measured during 108 TRH stimulation tests in 88 horses, and α-MSH concentrations were measured during 56 TRH st...
Blackhall WJ, Kuzmina T, von Samson-Himmelstjerna G.Resistance to benzimidazoles (BZ) in the gastrointestinal nematodes of livestock is characterised by the presence of specific polymorphisms in the β-tubulin isotype 1 protein, a component of microtubules. The most prevalent polymorphism associated with resistance in nematodes infecting cattle, sheep, and goats is found at codon 200, with minor occurrences of polymorphisms at codons 167 and 198. In the cyathostomins that infect horses, however, a polymorphism at codon 167 appears to be more common than the codon 200 polymorphism. In the present study, a focussed analysis of PCR-amplified β-tu...
Nemoto M, Ohta M, Tsujimura K, Bannai H, Yamanaka T, Kondo T, Matsumura T.We evaluated loop-mediated isothermal amplification (LAMP) as a means of detecting equine herpesvirus type 1 (EHV-1) DNA directly from nasal swabs. To increase the sensitivity, we added a step in which the samples were heat-treated to the original LAMP procedure. The detection limit of the LAMP assay with heat treatment was 10 times more sensitive than the original LAMP assay even when the DNA extraction step was omitted. In addition, the LAMP assay with heat treatment was more sensitive than the original LAMP assay and the polymerase chain reaction using clinical samples. The LAMP assay with ...
Ireland JL, McGowan CM, Clegg PD, Chandler KJ, Pinchbeck GL.This study reports on aspects of preventive health care and on the prevalence of disease in geriatric (≥30 years old) horses and ponies in North-West England and North Wales. Of 128 questionnaires mailed to horse owners, 87 useable responses were received and 69 horses were subject to veterinary examination. Of the animals examined, 16% were underweight with body condition scores (BCS)3/5). This contrasted with the owner responses that reported 23% of the animals surveyed to be underweight and only 3% to be overweight. When assessed at trot, 77% of the horses were lame on at least one limb, ...
Taylor SD, Leib SR, Wu W, Nelson R, Carpenter S, Mealey RH.Using the equine infectious anemia virus (EIAV) lentivirus model system, we previously demonstrated protective effects of broadly neutralizing immune plasma in young horses (foals) with severe combined immunodeficiency (SCID). However, in vivo selection of a neutralization-resistant envelope variant occurred. Here, we determined the protective effects of purified immunoglobulin with more potent broadly neutralizing activity. Overall, protection correlated with the breadth and potency of neutralizing activity in vitro. Four of five SCID foals were completely protected against homologous challen...
Sponseller BA, Sponseller BT, Alcott CJ, Kline K, Hostetter J, Reinertson EL, Fales-Williams A.Syringomyelia and hydromyelia are cavitary lesions of the spinal cord that may be acquired or congenital. These lesions are not frequently reported in large animal species. The presenting complaints, clinical, gross pathological, and histopathologic findings of 2 cases of syringomyelia and 1 case of hydromyelia in horses are described. La syringomyélie et l’hydromyélie sont des lésions cavitaires de la colonne vertébrale qui peuvent être acquises ou congénitales. Ces lésions ne sont pas fréquemment signalées chez les espèces de grands animaux. Les plaintes de présentation et les ...
Marlow CH.Horse breeding in South Africa started in 1652, shortly after the 1st European settlement in the Cape. African horsesickness posed a serious problem and after a devastating outbreak of the disease in 1719, horses were largely replaced by oxen for agricultural and transport purposes but remained important from a sporting and military point of view. Examples of the latter are the export of horses for military use to India in the mid-19th century and for use in the Crimean War in 1854, reaching a zenith in the Anglo-Boer war in which an estimated 450 000 horses succumbed. Research and disease con...
Ehizibolo DO, Gusi AM, Ehizibolo PO, Mbuk EU, Ocholi RA.Despite the endemicity of brucellosis in Nigeria, reports on equine brucellosis are rare. The Rose Bengal Plate Test (RBPT) was used to determine the serologic prevalence of Brucella abortus antibodies amongst 75 horses from three stables in two States of northern Nigeria. The highest prevalence (22.7%) was recorded in stable C located in Plateau State and the lowest (6.7%) was found in stable B in Kaduna State. The overall prevalence determined was 14.7%. There is need for the inclusion of horses in brucellosis surveillance and control strategies in Nigeria to safeguard people at high risk.
Dunowska M, Howe L, Hanlon D, Stevenson M.The significance of infection with Equid herpesvirus 2 (EHV-2) remains unresolved, mainly due to its widespread distribution, and frequent isolation of the virus not only from diseased animals, but also from clinically normal horses. It has been suggested that EHV-2 exerts its effects on the host indirectly, through predisposition to secondary infections. The aim of this study was to determine kinetics of EHV-2 infection among foals and to investigate the role that EHV-2 may play in development of Rhodococcus equi pneumonia on one farm. Serial blood samples were collected from 43 foals over a ...
Diab SS, Kinde H, Moore J, Shahriar MF, Odani J, Anthenill L, Songer G, Uzal FA.Clostridium perfringens type C is an important cause of enteritis and enterocolitis in foals and occasionally in adult horses. The disease is a classic enterotoxemia, and the enteric lesions and systemic effects are caused primarily by beta toxin, 1 of 2 major toxins produced by C. perfringens type C. Until now, only sporadic cases of C. perfringens type C equine enterotoxemia have been reported. We present a comprehensive description of the lesions in 8 confirmed cases of type C enterotoxemia in foals and adult horses. Grossly, multifocal to segmental hemorrhage and thickening of the intestin...
Mancill SS, Blodgett G, Arnott RJ, Alvarenga M, Love CC, Hinrichs K.3 sets of monozygotic twins resulting from transfers of single embryos to recipient mares were examined. Results: In all 3 recipient mares with twin pregnancies, only 1 embryonic vesicle was detected before day 25 of gestation. In 1 recipient mare, 2 apparent adjacent vesicles, each containing an embryo with a heartbeat, were visualized on ultrasonographic examination on day 37 of gestation. The other 2 recipient mares underwent ultrasonographic examination on day 30 of gestation, at which time only 1 vesicle and embryo was identified. In these latter 2 recipient mares, however, a thorough ult...
Vandekerckhove AP, Glorieux S, Gryspeerdt AC, Steukers L, Van Doorsselaere J, Osterrieder N, Van de Walle GR, Nauwynck HJ.Equine herpesvirus type 1 (EHV-1) replicates extensively in the epithelium of the upper respiratory tract, after which it can spread throughout the body via a cell-associated viremia in mononuclear leukocytes reaching the pregnant uterus and central nervous system. In a previous study, we were able to mimic the in vivo situation in an in vitro respiratory mucosal explant system. A plaquewise spread of EHV-1 was observed in the epithelial cells, whereas in the connective tissue below the basement membrane (BM), EHV-1-infected mononuclear leukocytes were noticed. Equine herpesvirus type 4 (EHV-4...
Franson JC, Hofmeister EK, Collins GH, Dusek RJ.We screened 1,397 feral horses (Equus caballus) on Sheldon National Wildlife Refuge, Nevada, United States, for IgM and IgG against flavivirus during 2004-2006, 2008, and 2009. Positive serum samples were tested for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis virus (SLEV). One animal was positive for antibody against WNV in 2004, but all others tested in 2004-2006 were negative. In 2008 and 2009, we found evidence of increasing seropositive horses with age, whereas seroprevalence of WNV decreased from 19% in 2008 to 7.2% in 2009. No horses were positive for anti...
Löhr CV, Polster U, Kuhnert P, Karger A, Rurangirwa FR, Teifke JP.Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass ...
Crafford JE, Guthrie AJ, Van Vuuren M, Mertens PP, Burroughs JN, Howell PG, Batten CA, Hamblin C.A polyclonal antibody-based, group-specific, competitive ELISA (C-ELISA) for the detection of antibodies to equine encephalosis virus (EEV) was developed. The assay measures the competition between a specific guinea pig antiserum and a test serum, for a pre-titrated EEV antigen. The C-ELISA detected antibodies to the seven known EEV serotypes. Reference antisera raised against other arboviruses did not cross react with EEV antigen. Negative sera from horses in the United Kingdom were used to establish the baseline for a negative population. Negative and positive populations of South African ho...
Thean S, Elliott B, Riley TV.During a 24 month period from 2007 to 2009, 174 faecal specimens from horses in Australia (predominantly from Western Australia) were tested for Clostridium difficile. C. difficile was isolated from 14 (23 %) of 62 diarrhoeal animals (including 10 foals) and from none of 112 healthy adult horses. These isolates were toxin profiled by PCR for toxin A, toxin B and binary toxin, and ribotyped. Ten of the equine isolates were A(+)B(+)CDT(-). Other toxin profiles detected were A(-)B(-)CDT(+) (one isolate), A(+)B(+)CDT(+) (two isolates) and A(-)B(-)CDT(-) (three isolates). There were six different...
Harris SP, Hines MT, Mealey RH, Alperin DC, Hines SA.Rhodococcus equi is an important respiratory pathogen of young foals for which a vaccine has long been sought. Two major impediments to effective vaccination are the functionally immature type I immune responses of neonatal foals and early exposure to the bacterium via the environment. Despite these obstacles, it appears that under specific circumstances foals can develop a protective immune response. In this study we investigated the protective mechanisms behind oral inoculation of foals with virulent R. equi bacteria. Two foals receiving an oral inoculum demonstrated accelerated development ...
Lassen ED, Swardson CJ.In diseased animals, laboratory evaluations of erythrocytes, leukocytes, and hemostasis provide important information that contributes to either narrowing the list of potential diagnoses or to determining a specific diagnosis. To adequately interpret the results of these evaluations, normal erythrocyte and leukocyte kinetics and normal hemostatic function must be understood. In addition, knowledge of common diseases resulting in abnormalities of these laboratory tests and of typical changes in these tests caused by these diseases is vital. This article has reviewed normal erythrocyte and leuko...
Moraveji M, Hosseini MH, Amrabadi O, Rahimian A, Namazi F, Namavari M.Neospora caninum, an apicomplexan protozoan parasite, is recognized as a major cause of abortion in cattle. However, limited information is presently available on the seroprevalence of Neospora antibodies in horses worldwide. The aim of the present study is to determine serological prevalence of Neospora infection in horses in Iran. Blood samples were obtained from 200 horses and tested for serum antibodies against Neospora spp. by the Neospora modified direct agglutination test (N-MAT). Antibodies were found in 64 (32%) horses being tested with titers of 1:80. This is the first serological su...
Sweeney CR, Beech J, Roby KA.Of tracheobronchial aspirates from 50 clinically healthy Thoroughbred racehorses, 4 (8%) had aerobic bacteria with recognized pathogenicity, 12 (24%) contained transient bacterial isolates, and 37 (74%) had no bacterial growth. Of tracheobronchial aspirates from 36 pastured, nonracing racehorses, 3 (8%) had bacteria with recognized pathogenicity, 23 (64%) contained transient bacteria, and 10 (28%) had no bacterial growth. Anaerobes were not isolated from 12 of 12 pastured horses. Transient bacteria were isolated more often in the pastured horses.
Marti E, Horohov DW, Antzak DF, Lazary S, Paul Lunn D.The horse has been human kind's most important partner throughout history. Similarly, in the field of immunology, many critical scientific advances have depended on the horse. Equine immunology today is an active and important field of study, with a focus on control of many common infectious diseases and immunopathologic conditions of broad comparative interest. In 2001 two major equine immunology workshops were held, in Santa Fe, USA, and in Hortobagy, Hungary, with major sponsorship from the Havemeyer Foundation. This report summarizes the scientific themes and foci of those meetings.
Bast TF, Whitney E, Benach JL.In September 1970 three horses in eastern Long Island were clinically diagnosed
as having Eastern equine encephalomyelitis (EEE). At this time, EEE virus was isolated
from the blood clots of three migrating Northern Yellow-shafted Flickers, and from the brain
and liver of another Northern Yellow-shafted Flicker (Colaptes auratus lutetts). Following
this episode, a I-year arbovirus survey was conducted beginning in September 1970. Serologic
surveys indicated widespread prevalence of EEE antibodies in the avian population and also
low grade activity in various mammals. Powassan and St. Lou...
Burger NC, Nesvadba J, Nesvadba Z, Busato A, Gottstein B.A cross-sectional field study on the prevalence of Dicrocoelium dendriticum was performed in the Emmental. The study included 211 bovines, 170 equines, 20 ovines, 46 caprines and 23 rabbits (from 119 farms). In addition, laboratory routine diagnostic data obtained from 2.840 animals--all originating from the same area of investigation--were assessed in the same way. The infection extent concerning the different animal species were the following: bovines 46%, equines 12%, ovines 30%, caprines 48% and rabbits 9%. Univariate analyses of baseline epidemiological data identified no significant risk...
van der Velden MA.During a seven year period, 51 cases of acquired inguinal herniation in 50 stallions were treated surgically. In 25 cases the herniated loop was ileal, in the other 26 it was jejunal. In cases of strangulation, the vaginal ring was enlarged by incising the peritoneum and transverse fascia. Closure of the superficial inguinal ring was advisable to prevent the hernia recurring. In all cases unilateral castration was performed. Laparotomy was carried out in 33 cases; 22 required intestinal resection and in four cases a bypass was made. Follow-up at least six months postoperatively indicated that ...
Prescott JF, Srivastava SK, deGannes R, Barnum DA.A mild form of strangles caused by an atypical Streptococcus equi was recognized on a large horse breeding farm. The organism differed from most S equi isolates by disappearance of the mucoid capsule by 24 hours of culture, leaving a matt-type colony. Typically, the clinical signs were a transient (24-48 hour) fever, profuse nasal discharge, and anorexia. In about half the affected animals, there was moderate mandibular lymph node enlargement, and these glands usually ruptured or were drained. The use of a passive hemagglutination antibody test showed that subclinical infection was widespread ...
Stephen JO, Baptiste KE, Townsend HG.To describe clinical signs and clinicopathologic findings in donkeys with hypothermia. Methods: Retrospective study. Methods: 10 hypothermic donkeys. Methods: Information on signalment, history, physical examination findings, results of diagnostic tests, treatments, and necropsy findings was extracted from medical records of all donkeys with hypothermia between 1988 and 1998 and compared with information from medical records of all normothermic donkeys and hypothermic horses admitted to the hospital during the same period. Results: Donkeys were more likely to be hypothermic than horses. The me...
Rossdale PD, Pattle RE, Mahaffey LW.A SYNDROME in newborn thoroughbred foals, characterized by irregular respiration, convulsions, and lung pathology, has been described already1, and its resemblance to the respiratory distress syndrome of the newborn human noted. This latter condition is associated with the absence of the surface active lung lining complex, or lung surfactant2; this absence can be investigated by observation of bubbles obtained from the lung3. From normal lungs bubbles of very low surface tension which show great stability in air-saturated water can be obtained4,5. The present case demonstrates the common facto...
Lyons ET, Tolliver SC, Collins SS, Drudge JH.Research carried out during the last 4 years (1996-1999) of an 11-year study of the prevalence of internal parasites naturally transmitted to horse foals born on the same pasture on a farm in central Kentucky is presented here. Horses in this herd were not treated with any antiparasitic compound for over 20 years except for a replacement stallion in 1994. A total of 22 species, including 12 species of small strongyles, were recovered in the 4-year period. Transmission patterns of all species (n=35) of endoparasites recovered are compared for the 11-year study. Some of the changes were an incre...
Ruszczyk A, Cywinska A, Banbura MW.The prevalence of Equine herpesvirus 2 (EHV-2) infections in the horse populations in Poland was investigated. Peripheral blood leukocytes (PBLs) of 139 horses were tested. The animals were divided into four groups: clinically healthy horses, horses suffering from respiratory disorders, mares with a recent abortion and horses with diagnosed ataxia. Thirty-four virus isolates were obtained from leukocytes of the tested animals by cocultivation with equine dermal cells and were identified as EHV-2 by PCR using primers for the gB gene of EHV-2 and/or primers for the sequence located upstream of t...
Mair TS.The clinical features of 18 cases of summer pasture associated obstructive pulmonary disease were reviewed. The horses had signs of obstructive pulmonary disease (expiratory dyspnoea, wheezing and crackling lung sounds and coughing) during the spring, summer or autumn while they were kept permanently at grass with no access to hay or straw, for at least two consecutive years. In nine cases there was a seasonal incidence with the disease occurring during April and May. Eleven of the horses were affected by bouts of severe dyspnoea. Eleven of the horses also suffered from chronic obstructive pul...
Jose-Cunilleras E, Hinchcliff KW.Listeria monocytogenes rarely causes disease in horses
(Emerson and Jarvis 1968; McCain and Robinson 1976; Clark et
al. 1978; Welsh 1983; Wallace and Hathcock 1995; Larochelle et
al. 1999; Wilkins et al. 2000). It is described as a cause of
abortion, septicaemia in equine neonates, mature horses and
ponies and neurological disease in a foal (Emerson and Jarvis
1968; McCain and Robinson 1976; Clark et al. 1978; Welsh
1983; Wallace and Hathcock 1995; Larochelle et al. 1999;
Wilkins et al. 2000). Most cases of listeriosis in other species
arise from the ingestion of contaminated food and...
Slater J.Josh Slater looks back at the past 125 years of developments in equine infectious disease, including landmark discoveries in microbiology and genomics, and considers what the future may hold.
TOMCSIK J, SCHWARZWEISS H.1. From beef stroma pretreated at room temperature with acetone and alcohol, a fraction was isolated with boiling 100% alcohol which, in a dilution of 1:500,000, combines with the sheep blood agglutinin of human serum produced during serum sickness. Using the terminology of Schiff, this fraction corresponds to the heterogenetic serum sickness antigen; it could be separated to a large extent from the heterogenetic mononucleosis antigen which also occurs in beef stroma.
2. The so-called serum sickness antigen also occurs heterogenetically in guinea pig kidney and it could also be isolated from ...
Tennent-Brown B.Although a range of plasma-based products (e.g., cryoprecipitate, albumin, platelet-rich plasma, individual coagulation factors) are available to human physicians, equine veterinarians are largely restricted to using whole blood, frozen plasma, and fresh frozen plasma for transfusions. The indications for frozen or fresh frozen plasma in human medicine are relatively limited, and there is little evidence supporting the efficacy of these products in many cases. Furthermore, many human physicians have concerns regarding disease transmission and anaphylactic reactions after administration of any ...
Messer NT, Johnson PJ.The evidence-based literature pertaining to thyroid dysfunction and Cushing's syndrome is discussed in this article. Summaries of and recommendations for the treatment of these conditions are made. There is a need for reliable diagnostic tests for these conditions in horses.
Speirs VC, Reynolds WT.The diagnosis and successful surgical treatment of a diaphragmatic hernia in a 12 weeks old standardbred foal are described. The clinical syndrome in horses generally is contrasted with that seen in the foal described in this paper. Some of the factors contributing to the clinical signs are discussed.
Skalka B, Svastová A.Two techniques were developed to detect antibodies against the exosubstance of C. equi called equi-factor. In the first technique serum samples are tested against native equi-factor produced by the growth of C. equi on agar medium. A positive result is manifested by the development of precipitation lines. The second test is based on neutralization of prepurified equi-factor by antibody, resulting in the inhibition of its hemolytic synergism with staphylococcal beta toxin. Sera (125 samples) from horses of different ages, kept in localities with a history of C. equi infections, were examined. T...
Clarke AF, Madelin TM, Allpress RG.The relationship between air hygiene within two types of identically managed horse housing and the incidence of covert respiratory disease (as revealed by endoscopic examination) of their inhabitants was assessed. The horses were all under the supervision of the same trainer. In one yard the design ensured the boxes were well ventilated in still air conditions. In the other yard the boxes were insulated and there was little provision for natural ventilation in still air conditions. There was heavy fungal and actinomycete contamination of wood shavings in the heavily insulated, poorly ventilate...
