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.
Mellor DJ, Love S, Walker R, Gettinby G, Reid SW.Details of the management, feeding, level of activity and routine health care of horses in Scotland and the five northernmost counties in England were recorded through a stratified random sample of horse owners who had responded to a previous survey. Sixty-eight per cent of the horses were kept where their owners resided, and 32 per cent were kept away from the owner's home. More than 99 per cent were turned out to grazing for at least part of the year and 81 per cent were stabled for at least part of the time, most commonly bedded on straw (50 per cent) or shavings (34 per cent). Hay was fed ...
Tecles F, Cerón JJ.Whole blood cholinesterase was measured using acetyl-, butyryl- and propionylthiocholine as substrates in 10 healthy adult dogs, cats, horses, pigs, goats, sheep and cows, in order to determine and characterise the cholinesterase activity in whole blood of the main domestic animals. An in vitro exposure test with two anticholinesterase compounds, the organophosphate insecticide coumaphos and the carbamate insecticide imidocarb, was also performed. In whole blood of ruminants and pigs, acetylthiocholine yielded the highest cholinesterase activity and other substrates were poorly hydrolysed; in ...
McTaggart C, Yovich JV, Penhale J, Raidal SL.Flow cytometric assays were used to compare phagocytic and oxidative burst activity of neutrophils from healthy foals less than 7 days of age with the activity of cells from healthy adult horses. The phagocytosis of Staphylococcus aureus by foal neutrophils was less than that observed for adult neutrophils when autologous serum was used as the source of opsonins in the assay. The use of adult serum did not significantly improve the ability of foal neutrophils to attach bacteria. The oxidative burst activity of foal neutrophils was equivalent to that of adult cells. However, when serum or plasm...
Miyazaki S, Fukumura M, Yoshioka M, Yamanaka N.From 1997 to 1999, 29 cases of disorders were detected in cattle and horses that had been fed ryegrass straw imported from the U.S.A. These animals showed symptoms resembling ryegrass staggers and the clinical signs disappeared after removal of the straw. Endophytic hyphae were detected in the seeds of all straw samples that were responsible for the clinical cases. Lolitrem B concentrations in the straw ranged between 972 and 3740 ppb. Ergovaline concentrations were between 355 and 1300 ppb. Even though the concentrations of lolitrem B were lower than the toxic threshold proposed by Oregon Sta...
May KA, Pleasant RS, Howard RD, Moll HD, Duesterdieck KF, MacAllister CG, Bartels KE.Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy was attempted in a mare and a gelding with calculi in the urinary bladder. The procedure was unsuccessful in producing adequate fragmentation of the calculi. In the gelding, pulsed dye laser lithotripsy was subsequently used to fragment the urolith. Manual removal of the urolith via the urethra was performed in the mare.
Textor JA, Goodrich L, Wion L.An 8-hour-old Standardbred filly was evaluated because of an enlarging umbilical mass and stranguria. It was suspected that the mass was the urinary bladder; this was confirmed on surgical exploration of the abdomen. Despite a normal umbilical ring, the bladder had descended and partially everted through its urachal communication with the umbilical stalk. Partial cystectomy and umbilical resection were performed and resulted in an excellent clinical outcome. Evagination of the urinary bladder via the umbilicus has rarely been described in human infants, and, to our knowledge, it has not been r...
Varrasso A, Dynon K, Ficorilli N, Hartley CA, Studdert MJ, Drummer HE.To develop and validate specific, sensitive and rapid (< 8 hour) diagnostic tests using polymerase chain reaction (PCR) for the diagnosis of abortion and respiratory disease caused by equine herpesvirus 1 (EHV1; equine abortion virus) and EHV4 (equine rhinopneumonitis virus). Methods: Primer sets based on nucleotide sequences encoding glycoprotein H (gH) of EHV1 and gB of EHV4 were designed and used in single round and second round (seminested) PCRs, and in a multiplex PCR for the diagnosis of EHV1 and EHV4 infections. Methods: Oligonucleotide primers were designed for each virus, PCR condi...
Laan TT, van Nieuwstadt RA, Sloet van Oldruitenborgh-Oosterbaan MM, Breukink HJ.Equine pulmonary disease and especially the terminology of lower airway disease have been subject to discussion. Besides established terms such as 'Chronic Obstructive Pulmonary Disease' (COPD) and Chronic bronchitis, the term 'small airway disease' (SAD) has been introduced, for respiratory disease with inflammation in the lower airways in combination with exercise intolerance. Bronchoalveolar lavage (BAL) enables the practitioner to diagnose SAD in an early stage when there are no other signs such as coughing or exudate in the trachea. The BAL fluid is microscopically examined after centrifu...
Martin-Downum K, Yazwinski T, Tucker C, Fincher M, Ralph J, Hamilton J.Commercial preparations of fenbendazole (Safe-Guard, Intervet), ivermectin (Eqvalan, Merial) or moxidectin (Quest, Fort Dodge) were administered once to horses scheduled for routine parasiticide treatment. In total, 93 horses from six cooperating farms were used in the study. Computer generated, random allocation of horses to treatment group was conducted at each farm. Fecal egg counts were determined for all horses on trial days 0, 56, 84 and 112, with corresponding calendar dates that were unique to each farm. Only strongyle egg counts from animals which were positive at day 0 were used for ...
Johnson DJ, Ostlund EN, Pedersen DD, Schmitt BJ.A traditional single-stage reverse transcription-polymerase chain reaction (RT-PCR) procedure is effective in determining West Nile (WN) virus in avian tissue and infected cell cultures. However, the procedure lacks the sensitivity to detect WN virus in equine tissue. We describe an RT-nested PCR (RT-nPCR) procedure that identifies the North American strain of WN virus directly in equine and avian tissues.
Varrasso A, Drummer HE, Huang JA, Stevenson RA, Ficorilli N, Studdert MJ, Hartley CA.The nucleotide and deduced amino acid sequences of the P1 region of the genomes of 10 independent equine rhinitis A virus (ERAV) isolates were determined and found to be very closely related. A panel of seven monoclonal antibodies to the prototype virus ERAV.393/76 that bound to nonneutralization epitopes conserved among all 10 isolates was raised. In serum neutralization assays, rabbit polyclonal sera and sera from naturally and experimentally infected horses reacted in a consistent and discriminating manner with the 10 isolates, which indicated the existence of variation in the neutralizatio...
Jang HK, Albrecht RA, Buczynski KA, Kim SK, Derbigny WA, O'Callaghan DJ.The sole immediate-early (IE) gene of equine herpesvirus 1 encodes a 1,487-amino-acid (aa) regulatory phosphoprotein that independently activates expression of early viral genes. Coimmunoprecipitation assays demonstrated that the IE protein physically interacts with the general transcription factor TFIIB. Using a variety of protein-binding assays that employed a panel of IE truncation and deletion mutants expressed as in vitro-synthesized or glutathione S-transferase fusion proteins, we mapped a TFIIB-binding domain to aa 407 to 757 of the IE protein. IE mutants carrying internal deletions of ...
Patterson-Kane JC, Sanchez LC, Uhl EW, Edens LM.A 12-year-old grey Warmblood stallion presented with fever of unknown origin, and anaemia. Five days later it had developed ataxia and become recumbent, and was humanely killed. At necropsy, malignant melanomas were identified in the perineal subcutis, spleen, and thoracic vertebral canal (T10-11). Populations of malignant melanoma cells were scattered throughout medullary cavities of the axial and appendicular skeleton, and were identified grossly as irregular areas of black to grey discoloration. To the authors' knowledge, this is the first report of disseminated intramedullary melanoma in a...
Furr M, Pontzer C, Gasper P.The percentages of T-lymphocytes, lymphocyte subsets CD4+ and CD8+ T-cells, and lymphocyte adhesion molecule CD11a/CD18 were determined in the peripheral blood and cerebrospinal fluid (CSF) of seven normal horses and four horses with equine protozoal myeloencephalitis (EPM) using flow cytometry. There was a greater percentage of CD5+ cells in the CSF (79.0%) than in peripheral blood (67.0%), although this did not achieve statistical significance. Furthermore, the lymphocyte population in CSF comprises a significantly greater (P = .01) percentage of CD8+ T-cells, resulting in a decrease of the ...
Nappert G, Johnson PJ.The purpose of the present study was to investigate the acid-base status and the concentration of organic acids in horses with colic caused by various disorders. Blood samples were collected from 50 horses with colic and from 20 controls. No intravenous fluids had been given prior to sample collection. Identified causes of colic included gastric ulceration, small intestinal volvulus, cecal intussusception, cecal rupture, colonic impaction, left dorsal colon displacement, right dorsal colon displacement, colonic volvulus, colitis, peritonitis, and uterine torsion. Thirty-seven horses recovered ...
Hahn CN, Mayhew IG, de Lahunta A.Equine grass sickness (EGS) is an acquired disease of unknown aetiology affecting horses kept at grass. The disease is characterised by postganglionic sympathetic and parasympathetic neuronal pathology and is categorised as a dysautonomia. This study undertook a systematic examination of brain stem cranial nerve nuclei in 59 cases of EGS. Pathology consisting of neuronal chromatolysis was most consistently noted in the lower motor neurons of the general visceral efferent nucleus of CN III and X and the general somatic efferent nuclei of CN III, V, VII and XII. The prevalence of chromatolysis d...
Beech DJ, Sibbons PD, Rossdale PD, Ousey JC, Holdstock NB, Chavatte P, Ansari T.Equine lung and kidney organogenesis has not previously been examined with the use of unbiased stereological techniques. The present study examined healthy (control) pony and Thoroughbred lungs and kidneys to establish baseline data of organ development from before birth until maturity at age 3-18 years. Whole left lungs and kidneys were collected from 45 equine postmortem examinations (34 Thoroughbred, 11 pony). Stereological techniques were used to estimate whole kidney, cortex and medulla volume, total glomerular number and volume-weighted mean glomerular volume, lung volume, total terminal...
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...
Stark G, Schneider B, Gemeiner M.Zinc concentration has been shown to have a potent immunomodulatory capacity, particularly influencing T helper cell organisation and cytokine secretion. Culicoides hypersensitivity (CHS) in horses resembles the early and late phase of type I hypersensitive reactions in man, characterised by a shift from T helper cell subtype 1 to T helper cell subtype 2 cytokine profile. In this pilot study, zinc and copper levels were measured in the plasma of 48 CHS-affected and 56 healthy Icelandic horses age 4-25 years (mean approximately 11 years) kept on 7 farms. Affected horses were divided into 3 grou...
Lillich JD, Frees KE, Warrington K, Van Harreveld PD, Gaughan EM, Beard WL.We report use of esophagomyotomy and esophagopexy to create a diverticulum for relief of chronic type I esophageal stricture in 2 horses. After esophagomyotomy, the mucosa was dissected free from the muscularis for approximately 180 degrees around the myotomy. Then, the tunica muscularis of esophagus was sutured to the sternocephalicus muscle ventrally and the periesophageal tissues dorsally to create a diverticulum without disruption of the esophageal mucosa. Clinical signs of esophageal stricture were relieved, and the horses were fed normal diets without further esophageal obstruction.
Allen WR.Four separate components combine to produce the progesterone and biologically active 5 alpha-reduced pregnanes needed to maintain pregnancy in the mare. The primary corpus luteum (CL) is prolonged beyond its cyclical lifespan by the down-regulation of endometrial oxytocin receptors to prevent activation of the luteolytic pathway and its waning progesterone production is supplemented from day 40 of gestation by the formation of a series of accessory CL which develop in the maternal ovaries as a result of the gonadotrophic actions of pituitary FSH and the equine chorionic gonadotrophin (eCG). Fr...
Labonville M, Higgins R, Lavoie JP.The aim of the study was to assess the relation between the direct smear observations and bacteriological results carried out on equine tracheal secretions. A total of 304 cases comprising both the direct smear (Gram stain) and the bacteriological culture, over a period of 8 years, were submitted to this retrospective study. Most of the specimens (78%) were obtained using tracheal washings while the rest (22%) originated from tracheal brushings. A total of 96 specimens (32%) were negative for both direct smear and culture. The positive predictive value of direct smears appeared high (81-96%) w...
Klei TR, Turk MA, McClure JR, Holmes RA, Dennis VA, Chapman MR.Eight of 10 pony foals reared under helminth-free conditions were inoculated PO with 50 Strongylus vulgaris infective larvae/week for 4 weeks, at which time 1 foal died of acute verminous arteritis. Inoculation of 7 remaining foals continued at 2-week intervals for 20 weeks. Of the 7 foals, 3 were treated with ivermectin (0.2 mg/kg of body weight) in an oral paste formulation at experiment weeks 8, 16, 24; 4 foals were not treated. Two foals were not inoculated or treated and served as controls. After the first ivermectin treatment, ivermectin-treated foals had fewer days (12 +/- 2.9) with rec...
Waller T, Rubarth S.The study comprises 49 dogs, 2 horses, and 2 cows with haemangioendothelioma, which have been subjected to autopsy over a period of 26 years. Most of the dogs were old, and there is an over-representation of male dogs. The results also indicate that the Alsation breed of dog is particularly susceptible to these tumours, as is the Boxer to some extent. The disease was in most cases of short duration and the most common clinical symptoms were sluggishness, fever, generalized anaemia, breathing difficulties, increased thirst, and leuco-cytosis. Most of the dogs fell ill and were subjected to auto...
Bustos CP, Marfil MJ, Lanza NS, Guida N.Streptococcus equi subsp. equi is the etiologic agent of strangles, an infectious disease affecting the upper respiratory tract and head and neck lymph nodes of equines. Routine antimicrobial therapy includes penicillin (PEN) as antibiotic of first choice. Streptococci are usually susceptible to PEN and only a few antimicrobial studies had been performed. The aim of this work was to study the antimicrobial susceptibility profile of S. equi from Buenos Aires, Argentina. Ninety-two isolates were studied by the single disk method to PEN, cefotaxime, erythromycin (ERY), tetracycline, enrofloxacin ...
Preiss EE, Kenney DG, McGurrin MK, Physick-Sheard PW.To evaluate influence of electrode position on cardioversion energy (CE; energy delivered in the shock at which cardioversion was achieved) during transvenous electrical cardioversion (TVEC) in horses with atrial fibrillation. Methods: 37 horses with atrial fibrillation (41 cardioversion events). Methods: Records were reviewed to identify horses that underwent TVEC for treatment of atrial fibrillation. Signalment and CE were recorded. Electrode positions in the right atrium and pulmonary artery were identified on intraoperative radiographs. An orthogonal coordinate space was created, and elect...
Dhama K, Kapoor S, Pawaiya RV, Chakraborty S, Tiwari R, Verma AK.A fascinating and important arbovirus is Ross River Virus (RRV) which is endemic and epizootic in nature in certain parts of the world. RRV is a member of the genus Alphavirus within the Semliki Forest complex of the family Togaviridae, which also includes the Getah virus. The virus is responsible for causing disease both in humans as well as horses. Mosquito species (Aedes camptorhynchus and Aedes vigilax; Culex annulirostris) are the most important vector for this virus. In places of low temperature as well as low rainfall or where there is lack of habitat of mosquito there is also limitatio...
Sukmawinata E, Sato W, Uemura R, Kanda T, Kusano K, Kambayashi Y, Sato T, Ishikawa Y, Toya R, Sueyoshi M.In this study, the occurrence of antimicrobial-resistant (AMR) enterococci was evaluated in Thoroughbred (TB) racehorses in Japan. Fecal samples were collected from 212 healthy TB racehorses at the Miho and Ritto Training Centers of the Japan Racing Association from March 2017 to August 2018. Isolation and identification were performed by enterococcus selective medium and confirmed to the species using MALDI-TOF MS. Enterococcus faecium and E. faecalis isolates were subjected to antimicrobial susceptibility test against 11 antimicrobials by minimum inhibitory concentration based on recommenda...
Santschi EM, LeBlanc MM, Weston PG.Plasma cortisol, oestrone sulphate and progestagens were measured in 22 stressed pregnant mares (gestation length 17-336 days) as indicators of fetal viability. Mares were bled every 12 h from time of admission, and plasma was stored at -70 degrees C until assayed. Four normal mares were bled twice weekly from Day 270 to parturition to provide baseline endocrine data. Cortisol and progestagen concentrations were measured by radioimmunoassay and oestrone sulphate was measured by enzyme immunoassay. Mares were grouped according to clinical diagnosis: surgical colic (Group 1, n = 11), medical col...
Ishii M, Aoki T, Yamakawa K, Magata F, Gojo C, Ito K, Kayano M, Nambo Y.The aim of this study was to clarify the relationship between the placental retention time (PRT) and the reproductive performance following mating at the foal heat in Thoroughbreds. For this purpose, we interviewed 292 farmers over a period of 3 years with questionnaires evaluating foaling, expulsion of placenta and reproductive performance at the foal heat in 1,432 mares. The obtained data were later compared with a previous study of heavy draft mares. The average of the PRT of the 1,432 Thoroughbred mares was 58 ± 88 min (mean ± SD). The mean PRT of Thoroughbreds was significantly shorter ...
Clayton HM, Duncan JL.Six worm-free pony foals, two to four months old, were infected with parascaris equorum eggs using three different dosage regimes and killed at either 40 or 95-100 days after infection. Coughing and a circulating eosinophilia were features of large infections from which only a small number of worms developed to maturity. In small infections a high percentage of the parasites matured in the small intestine and this was associated with unthriftiness. Pre-patent periods of 80 and 83 days were recorded.
Lean NE, Perkins NR, Ahern BJ.Conventional radiography is currently the most common imaging modality used by veterinarians investigating foals with suspected osteomyelitis. Emerging evidence in adult horses and humans suggests computed tomography (CT) is a superior modality for evaluation of osseous changes in general. This study aimed to evaluate the potential benefits of CT versus conventional radiography in cases of osteomyelitis in foals. Methods: Cases of osteomyelitis in foals under 6 months of age admitted over a 6-year period at a single referral hospital that had both CT and conventional radiography images were ...
Liebermann H.Sera collected from 124 horses were checked by means of the serum neutralisation test against equine Bern virus. Torovirusspecific antibodies were recordable from 35 percent of all horses tested. These results are likely to suggest that toroviruses are widespread in the GDR and occur not only in horses but in other domestic animals and in man, as well.
Scott EA, Kneller SK, Witherspoon DM.The physiologic closure of the ductus areteriosus was determined in 4 foals less than 16 hours old. The common carotid artery was catheterized, using local anesthesia and tranquilization, and contrast medium was injected into the ascending aorta. Radiographs were made of heart and great vessels during and after the injection to visualize the pathway of injected contrast medium.
Savage CJ.Defining respiratory disease is not always easy in the horse because auscultation with accurate interpretation of lung sounds can be difficult. However, performing a thorough physical examination, including rebreathing auscultation and percussion of the thorax and sinuses, is very useful in elucidating the problem. Endoscopic examination of the upper respiratory system is also critical for definitively diagnosing certain conditions.
Wilson DV, Nickels FA, Williams MA.Benztropine mesylate was used successfully to treat priapism that developed during anesthesia in 2 horses. After IV injection, there was a rapid resolution of signs in both horses, and no side effects were observed. The choice of an effective method to treat priapism is challenging because precise causes in most patients have not been well-defined. Benztropine mesylate is a synthetic compound resulting from the combination of the active portions of atropine and diphenhydramine, and is believed effective because of its central acetyl-choline-antagonizing properties.