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.
Kokotovic B, Angen Ø, Bisgaard M.Genetic diversity detected by analysis of amplified fragment length polymorphisms (AFLPs) of 54 Actinobacillus lignieresii isolates from different hosts and geographic localities is described. On the basis of variances in AFLP profiles, the strains were grouped in two major clusters; one comprising strains isolated from horses and infected wounds of humans bitten by horses and another consisting of strains isolated from bovine and ovine hosts. The present data indicate a comparatively higher degree of genetic diversity among strains isolated from equine hosts and confirm the existence of a sep...
Yamamoto H, Yamamoto F, Tanaka F, Nishikawa Y.We describe the influence of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia on histopathological alteration of a glutaraldehyde-fixed equine pericardial roll (EPR) graft in a 77-year-old male who underwent in-situ EPR replacement of a ruptured infected abdominal aorta with concomitant repair of the perforated duodenum. The patient died of circulatory failure after septic shock due to MRSA infection and gastrointestinal bleeding on postoperative day (POD) 23. The autopsy revealed no perforation of the EPR graft or anastomotic disruption between the native abdominal aorta and EPR ...
Wilkins PA.Rapid evaluation and intervention is a requirement and a characteristic of patient management in neonatal intensive care units, and this applies for equine neonates also. Appropriate interventions are based on solid knowledge of age, maturity, and species-specific differences in reference ranges. Point-of-care (POC) testing devices speedup decision making regarding treatments and interventions. However, there are potential limitations of these devices when applied to age groups and species beyond those they were specifically developed for. This article discusses the age-specific differences in...
Singh BR, Gulati BR, Virmani N, Chauhan M.At a thoroughbred equine breeding farm near Hissar (Haryana), three mares aborted in their seventh month of pregnancy. The vaginal swabs of all aborted mares, and stomach contents, heart blood, liver, spleen and placenta of aborted fetuses yielded pure culture of Aeromonas hydrophila. In addition, A. hydrophila was also isolated from the vaginal swabs of three repeat breeding mares and faecal sample of a diarrheic foal. The source of infection was possibly water supply as all the water samples collected from taps, mother tank and storage tank were found to be positive for A. hydrophila. The an...
Sanz MG, Wills TB, Christopherson P, Hines MT.A 17-year-old Peruvian Paso mare was evaluated for bilateral epistaxis that had been present for at least 3 years. The mare had mild anemia, platelet count within the reference interval, unremarkable coagulation times, and a negative Coggins test. On endoscopic examination, structural abnormalities were not observed in the nasal cavities, pharynx, larynx, trachea, or either guttural pouch, but petechiation was noted in the nasal mucosa. Additional tests revealed prolonged cutaneous bleeding time, normal concentration of von Willebrand factor antigen, an abnormal clot retraction test, and failu...
Romero AE, Rodgerson DH.Diaphragmatic rent and visceral herniation in the horse is seldom diagnosed, but historically carries a poor prognosis. The objective of this study was to document the presentation and surgical management of all diaphragmatic rents as presented to 2 referral institutions over a 5-year period. A review of 31 cases demonstrated that even with advances in surgical management of abdominal and thoracic conditions, little has been done to change the prognosis for this condition. Success rate was 23% for all horses presented for colic and were ultimately diagnosed with a diaphragmatic hernia, and 46%...
Berzina I, Trumble NS, Novicki T, Sharkey LC.An 11-year-old American Saddlebred gelding was presented for evaluation of a nonpainful subconjunctival mass involving the lateral canthus of the left eye. Other findings included a central corneal scar and a small central cataract of the lens in the left eye. Fine-needle aspiration of the mass was performed and cytologic examination revealed marked pyogranulomatous inflammation with intralesional fungal hyphae, consistent with mycetoma. The fungal structures were elongated and characterized by nonstaining walls; several bulbous yeast-like structures were also observed. The mycetoma was surgic...
Rudi K.Mainly due to the lack of time-series data, we know very little about the underlying interactions leading to adverse states in the gut. I therefore investigate the host-bacteria dynamic interactions in a recently published acidotic state induction time-series experiment. Too high levels of fermentation in the hindgut may lead to elevated serum lactate levels, which is a characteristic of the acidotic state. The acidotic state was induced through injection of oligofructose directly into the caecum of five horses, with subsequent temporal measurements of host serum lactate, and a range of caecum...
Hart KA, Barton MH, Ferguson DC, Berghaus R, Slovis NM, Heusner GL, Hurley DJ.Relative cortisol insufficiency occurs in septic foals and impacts survival. Serum free (biologically available) cortisol concentration might be a better indicator of physiologic cortisol status than serum total cortisol concentration in foals. Objective: In septic foals, (1) low free cortisol concentration correlates with disease severity and survival and (2) predicts disease severity and outcome better than total cortisol concentration. Methods: Fifty-one septic foals; 11 healthy foals; 6 healthy horses. Methods: In this prospective clinical study, foals meeting criteria for sepsis at admiss...
Hébert L, Moumen B, Duquesne F, Breuil MF, Laugier C, Batto JM, Renault P, Petry S.Taylorella equigenitalis is the causative agent of contagious equine metritis (CEM), a sexually transmitted infection of horses. We herein report the genome sequence of T. equigenitalis strain MCE9, isolated in 2005 from the urethral fossa of a 4-year-old stallion in France.
Meyer A, Messer L, De Briel D, Moreau P.The field of zoonoses changes constantly. Streptococcus equi subsp. ruminatorum is a group C Streptococcus subspecies first identified in 2004. The first case of human infection with this agent was reported in 2007. Here, we report a second case. A 70-year-old man had acute spondylodiscitis and endocarditis involving the anterior mitral valve leaflet. S. equi subsp. ruminatorum was identified in the blood cultures. Antibiotic therapy was successful in eradicating the infection. The workup showed hypogammaglobulinemia with stage I myeloma. He reported frequent contacts with horses including tw...
Castleman WL, Toplon DE, Clark CK, Heskett TW, Farina LL, Lynch TM, Bryant UK, Del Piero F, Murphy B, Edwards JF.This multi-institutional report describes 8 cases of rhabdomyosarcoma in horses. Four neoplasms were in the tongue and other areas of the mouth or head, 2 were in the abdominal wall, and 1 each was in right shoulder muscles and heart. Four rhabdomyosarcomas that were less than 10 cm in diameter were treated by surgical excision or radiation with no recurrence. Two neoplasms greater than 10 cm in diameter in the abdominal wall and the right shoulder were considered inoperable and led to decisions to euthanize the horses. Two neoplasms were incidental findings at necropsy. All the neoplasms were...
Schwarz BC, van den Hoven R, Schwendenwein I.The myeloperoxidase index (MPXI) was investigated as a diagnostic indicator of systemic inflammation in a retrospective study using data from 859 hospitalised horses. A reference interval of 8.5-10.4 for the MPXI was established. In horses with systemic inflammatory response syndrome (SIRS), the MPXI was significantly lower than in healthy horses, those with localised inflammation and those with sepsis. The MPXI in horses with sepsis was also significantly lower than in healthy animals and those with localised inflammation. Horses in the SIRS group with leucopenia, white blood cell (WBC) count...
Kitai Y, Shirafuji H, Kanehira K, Kamio T, Kondo T, Konishi E.West Nile virus (WNV) and Japanese encephalitis (JE) virus are distributed separately in the world with some exceptions. There is a concern that WNV may invade into Asia where JE virus exists. On and after such invasion, any differential diagnosis could be complicated by serological crossreactivities. We previously demonstrated experimentally using horses infected with WNV that preimmunization with inactivated JE vaccine considerably affected the ability of neutralization tests and immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (ELISA) to diagnose WNV infection. Here...
Hijazin M, Ulbegi-Mohyla H, Alber J, Lämmler C, Hassan AA, Prenger-Berninghoff E, Weiss R, Zschöck M.An Arcanobacterium haemolyticum strain isolated from a postcastrational lesion of a horse was identified phenotypically and genotypically. The latter was performed by sequencing the 16S-23S rDNA intergenic spacer region (ISR), by amplification of the gene encoding A. haemolyticum phospholipase D, by amplification of A. haemolyticum specific parts of ISR-23S rDNA and by amplification of the newly described CAMP factor family protein encoding gene of A. haemolyticum. This indicates (as described previously for seven additional A. haemolyticum strains; Hassan et al. 2009) that A. haemolyticum see...
Arenas-Gamboa AM, Mansell J.Haemangiosarcomas (HSAs) are malignant tumours of endothelial cell origin. Epithelioid HSA is a variant of the histologically conventional HSA that has little or no morphological evidence of a vascular origin and has been reported rarely in domestic animals. The following report documents six cases of equine epithelioid HSA occurring in the ocular tissues of horses with a mean age of 19.8 years at the time of diagnosis. Microscopically, all of the lesions consisted of solid sheets or cords of epithelioid cells with rare narrow clefts or small spaces containing erythrocytes that were often the ...
Mendoza FJ, Perez-Ecija RA, Estepa JC.Emphysema of lymph nodes is a rare finding that has been described in different anatomical locations and related to specific diseases in different animal species. Herein is described a foal with Rhodococcus equi infection that presented with emphysema and granulomatous inflammation of the bronchial and mediastinal lymph nodes. This is the first report of emphysematous lymphadenitis in a horse.
Visser MB, Pollitt CC.The timing of lamellar basement membrane (BM) changes occurring during laminitis development is incompletely understood. Objective: To determine the temporal progression of lamellar BM changes and whether laminin-332 (Ln-332) γ2 cleavage products are generated during laminitis development. Methods: Eight clinically normal Standardbred horses were allocated into treatment (n = 5) or sham (n = 3) groups. The treatment group received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt) while the sham group was given water. Laminitis induction proceeded for 48 h followed by euth...
Sonmez K, Gurel A, Takai S.The aim of the present study was to develop an immunocytochemical procedure for the early detection and demonstration of Rhodococcus equi in smears of tracheal aspirates taken from live foals in field conditions. Tracheal wash samples were collected from thoroughbred foals, aged 1-5 months and located in studs around Bursa and Istanbul, Turkey. Some foals were suspected of having R. equi infection on the basis of clinical examination (n=56) and others were unaffected control animals (n=54). Serum samples were also collected from each foal for testing for the presence of R. equi-specific antibo...
Schurink A, Ducro BJ, Heuven HC, van Arendonk JA.Insect bite hypersensitivity (IBH) is a seasonal allergic skin disease in horses caused by bites of certain Culicoides spp. The aim of our study was to investigate the maternal effect on IBH and to estimate the heritability and repeatability of IBH in the Dutch Friesian horse population. Data consisted of 3,453 Dutch Friesian broodmares with 3,763 visual observations on IBH clinical symptoms scored by 12 inspectors during organized foal inspections in 2004 and 2008. Nine percent of the mares (n = 310) were scored in both years. Mares descended from 144 sires and 2,554 dams and 26.2% of the dam...
Ryan PL, Christiansen DL, Hopper RM, Walters FK, Moulton K, Curbelo J, Greene JM, Willard ST.Uterine and placental infections are the leading cause of abortion, stillbirth, and preterm delivery in the mare. Whereas uterine and placental infections in women have been studied extensively, a comprehensive examination of the pathogenic processes leading to this unsatisfactory pregnancy outcome in the mare has yet to be completed. Most information in the literature relating to late-term pregnancy loss in mares is based on retrospective studies of clinical cases submitted for necropsy. Here we report the development and application of a novel approach, whereby transgenically modified bacter...
Castillo-Olivares J, Mansfield KL, Phipps LP, Johnson N, Tearle J, Fooks AR.West Nile virus (WNV) has re-emerged as an important pathogen for humans and horses, which are considered to be incidental 'dead-end' hosts. We have demonstrated that horses are susceptible to experimental infection with WNV and that horses infected with either WNV lineage 1 or lineage 2 elicit a similar antibody profile in serum samples. These data suggest that virus-neutralizing antibody responses persist for longer than WNV-specific IgM levels in serum and that there are not any notable differences in the antibody profile following experimental infection of horses with either WNV lineage 1 ...
Lengacher B, Kline TR, Harpster L, Williams ML, Lejeune JT.Manure from draft animals deposited in fields during vegetable and fruit production may serve as a potential source of preharvest pathogen contamination of foods. To better quantify this risk, we determined the prevalence of Escherichia coli O157:H7 in horses. Between June and September 2009, freshly voided fecal samples were collected from horses stabled on 242 separate premises in Ohio, USA. Overall, the prevalence of E. coli O157:H7 was 1 of 242 (0.4% prevalence, 95% confidence interval [CI] = 0.01 to 2.28). E. coli O157:H7 was recovered from none of the 107 equine fecal samples (0% prevale...
Aanes WA.The great variety of pathologic conditions associated with the peripartum period in the mare emphasizes the need for close observation and evaluation of the mare's condition during this period. The temperament and strength of the mare and violence of parturition undoubtedly produce extreme intraabdominal pressures that result in (or enhance preexisting) pathologic changes. Although the exact etiology of many of these disease processes is unknown, careful observation with properly timed medical and/or surgical intervention could reduce the losses associated with the peripartum period.
Herd RP.The serious and widespread problem of drug resistance has forced a re-thinking of basic philosophy regarding control of equine parasites. It has illustrated the dangers of total reliance on chemical control and stimulated the use of alternate strategies. Two new approaches are described. Prophylactic treatments in the spring and summer provide effective strongyle and colic control with less selection pressure for drug resistance. A nonchemical approach of pasture cleaning twice a week offers the same advantages with the added bonus of a 50 per cent increase in grazing area.
Ireland JL.Gerontology has become increasingly important in equine veterinary medicine, with aged animals representing a significant proportion of the equine population. Horses are defined as geriatric or aged from age 15 years onwards but can have a life span of more than 40 years. Despite a high level of owner concern for the well-being of their geriatric animal, provision of preventive health care may be suboptimal. Owners seem to under-recognize some of the most prevalent diseases identified in geriatric horses. This review focuses on the demographic characteristics of the equine geriatric populati...
Castleman WL, Toplon DE, Clark CK, Heskett TW, Farina LL, Lynch TM, Bryant UK, Del Piero F, Murphy B, Edwards JF.This multi-institutional report describes 8 cases of rhabdomyosarcoma in horses. Four neoplasms were in the tongue and other areas of the mouth or head, 2 were in the abdominal wall, and 1 each was in right shoulder muscles and heart. Four rhabdomyosarcomas that were less than 10 cm in diameter were treated by surgical excision or radiation with no recurrence. Two neoplasms greater than 10 cm in diameter in the abdominal wall and the right shoulder were considered inoperable and led to decisions to euthanize the horses. Two neoplasms were incidental findings at necropsy. All the neoplasms were...
Nakajima H, Norcross NL, Coggins L.Antigenic relationship between purified equine infectious anemia (EIA) virus and spleen-derived antigen from EIA-infected horses was examined by immunodiffusion. Identical antigenicity of these two antigens has been proven because precipitation lines formed between the two antigens and EIA antiserum connected with each other. The results indicate that the antigenic substance derived from infected spleen is a component of EIA virus.
Ramadan RO.The clinical features and pathology of an ocular melanoma in a young born-grey mare are described. The tumour, possibly arising on the cornea, invaded the eye and extra-orbital muscles. Histologically; it consisted predominantly of spindle-shaped and polygonal cells containing melanin.
Aleman M, Costa LRR, Crowe C, Kass PH.Neuroglycopenia refers to a shortage of glucose in the brain resulting in neuronal dysfunction and death if left untreated. Presumed neuroglycopenia has not been described in horses. Objective: To report neurological signs in horses with presumed neuroglycopenia as the result of severe hypoglycemia. Methods: Ninety horses (hours to 28 years of age) diagnosed with hypoglycemia (blood glucose concentration < 75 mg/dL [< 4.2 mmol/L]). Methods: Retrospective study. Electronic medical records were searched. Signalment, history, complaint, clinical signs, laboratory findings including CSF analysis, ...
Niwa H, Anzai T, Izumiya H, Morita-Ishihara T, Watanabe H, Uchida I, Tozaki T, Hobo S.In this study, we examined the antimicrobial susceptibility of 16 Salmonella Typhimurium isolates obtained from horses, and applied several genetic methods, namely polymerase chain reaction (PCR) for detecting class 1 integrons, multiplex PCR for detecting multidrug resistant S. Typhimurium definitive phage type 104 (MR-DT104), and fluorescent amplified-fragment length polymorphism (FAFLP). Seven isolates with an ampicillin, chloramphenicol, streptomycin, sulfonamide, and tetracycline (ACSSuT) type resistance pattern, harbored two class 1 integrons with sizes of 1.2 and 1.0 kb, and were identi...
Allen K, Franklin S.The effect of palatal instability (PI) on measures of ventilation and gas exchange is not well understood. Objective: To assess to what degree different severities of naturally occurring palatal dysfunction affect ventilation and gas exchange during strenuous exercise. Methods: A retrospective study was performed using data collected from 40 Thoroughbred racehorses diagnosed with naturally occurring dynamic palatal dysfunction during high speed treadmill exercise. Upper airway videoendoscopic recordings were made concurrently with measurements of ventilation and gas exchange. Three categories ...
Easton C, Fuentealba NA, Paullier C, Alonzo P, Carluccio J, Galosi CM.Equine herpesvirus 1 (EHV-1) is a major cause of epidemic abortion, neonatal mortality, respiratory disease and neurological disorders in horses. In South America, the virus has been isolated in Brazil, Argentina and Colombia. In Chile pathological findings from one aborted foetus have been reported, and in Uruguay only serological data about EHV-1 activity have been found. Some pathological findings were reported in Uruguay several years ago, but these data have never been officially confirmed. The present work describes the relevant findings of a study of EHV-1 infections in the Uruguayan eq...
Wray C, Sojka WJ, Bell JC.During the period 1973 to 1979 the number of recorded incidents of equine salmonellosis increased from 23 in 1973 to a peak of 111 incidents in 1976, but has since decreased to 32 in 1979. Of the 416 incidents recorded during the period of the survey 292 were caused by Salmonella typhimurium and 121 by 33 different serotypes; in three instances rough strains of salmonella were involved. The number of incidents caused by serotypes other than S typhimurium increased from one in 1973 to 32 in 1976. The number of different salmonella serotypes increased from two in 1973 to 23 in 1977 and has subse...
van Maanen C, Willink DL, Smeenk LA, Brinkhof J, Terpstra C.An outbreak of EHV1 abortions occurred at a riding school in The Netherlands in 1991. Seven of twelve pregnant mares aborted, and another foal died at 8 days of age. Six abortions occurred within 12 days in March after an initial abortion on 8 February. Four mares delivered live foals. Virological examination of four aborted foals revealed an EHV1 infection. Serological results for paired sera from 17 horses suggested, that the initial abortion on 8 February was the index case, and probably caused the other six abortions. The index case could well have been caused by reactivation of latent vir...
Onyekaba C, Bueon L, King P, Fahrmann J, Goyal SM.A comparative study was carried out to determine the susceptibility of five different cell lines to pseudorabies virus (PRV), a herpes virus of pigs. The cell systems tested were swine testicle (ST), mink lung (ML), equine dermal (ED), porcine kidney (PK15), and bovine turbinate (BT) cells. Virus titers obtained were 10(4.88), 10(4.38), 10(3.75), 10(2.63), and 10(0.25) for ML, ST, PK15, BT and ED cells, respectively indicating that ML, ST, and PK15 are optimal cell lines for the growth of PRV whereas BT and ED are not very sensitive.
Gunsen U, Yaroglu T.Aflatoxin levels were determined by ELISA in 18 dog and 20 horse feed samples, collected from different firms from June 2000 to June 2001 in Turkey. The minimum and maximum levels of total aflatoxin in the dog and horse feeds were <1.75-20 microg/kg and <1.75-14 microg/kg, respectively; 3/18 dog feed samples (16.7%) and 2/20 horse feed samples (10%) exceeded the Turkish tolerance limit of 10 microg/kg in food or feed.
Shen DT, Gorham JR, McGuire TC.An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of equine infectious anemia (EIA) antibody in horse sera. Purified P26 viral protein was the antigen; alkaline phosphatase linked to rabbit anti-horse immunoglobulin G was the conjugate. The ELISA detected EIA antibodies in horse sera as early as 11 to 14 days after experimental inoculations. There was full agreement between the results of ELISA and the agar-gel immunodiffusion tests on EIA proficiency test sera. The ELISA readily detected EIA antibody in horse sera that had weak positive reactions on agar-ge...
Carrasco L, Mendez A, Jensen HE.An atypical case of chronic equine bronchopulmonary aspergillosis with an unusual hyphal morphology was diagnosed in a horse with Cushing's syndrome. Because of the hyphal localization in chronic ectatic bronchi and bronchioles, and juxtabronchiolar processes, the observed type of aspergillosis is similar to 'saprophytic bronchopulmonary aspergillosis' or 'semi-invasive pulmonary aspergillosis' in humans. The aetiological diagnosis of aspergillosis was accomplished by the application of a panel of monospecific polyclonal and monoclonal antibodies in immunohistochemical techniques.
Rebhun WC, Shin SJ, King JM, Baum KH, Patten V.Malignant edema (clostridial myositis) was diagnosed in 9 horses with signs of illness that included fever, depression, painful muscular swellings, and toxemia. The infection followed intramuscular injections in 8 horses and developed in a puncture wound in 1 horse. Treatment consisted of surgical fenestration of the involved muscle, high doses of penicillin, nonsteroidal anti-inflammatory agents and analgesics, and supportive fluid therapy. Five horses recovered and 4 died. Those that died had advanced signs of the disease at admission.
MacMillan AP, Cockrem DS.Five mares and a stallion were studied from three to 30 months after experimental infection with Brucella abortus strain 544. The mares bred normally. No organisms were recovered from horses or from pregnant Friesian heifer contacts. Titres of serum antibody in the antiglobulin (Coombs) and complement fixation tests fell more slowly than those assessed by other tests. The serum of one foal yielded maternal antibody. An intradermal test was positive in infected adults only, and negative in all foals.
Caltabilota TJ, Earl LR, Thompson DL, Clavier SE, Mitcham PB.Four experiments were conducted 1) to assess the use of glucose responses to insulin injections as a means of estimating insulin sensitivity in horses and 2) to compare the insulin sensitivities of normal horses vs. those displaying hyperleptinemia (HL). In Exp. 1, HL mares and geldings (n = 4 each) and 4 mares and geldings with normal leptin concentrations (NL) were injected intravenously with 20 and 100 mU/kg of BW of bovine insulin on 2 separate occasions in December 2008. In Exp. 2, the experimental protocol was repeated in late April 2009. In Exp. 1, the 20 mU/kg of BW dose of insulin cau...
Sykes CA, Uzal FA, Mete A, Ochoa J, Filigenzi M, Poppenga RH, Asin J.A presumptive postmortem diagnosis of oleander () poisoning is made based on the histological observation of cardiomyocyte degeneration and necrosis, which is considered to be a reliable diagnostic marker, and can be confirmed via the detection of oleandrin in tissues or fluids. However, cardiac lesions may not be present in every case, and autolysis can often preclude the identification of subtle changes in the cardiomyocytes. Several studies of experimental oleander poisoning have noted the presence of renal lesions in multiple mammalian species, and case studies of accidental exposure have ...