Disease etiology in horses refers to the study of the causes and development of diseases within equine populations. It encompasses various factors, including genetic predisposition, environmental influences, infectious agents, and nutritional imbalances, that contribute to the onset and progression of diseases in horses. Understanding disease etiology is essential for identifying risk factors and implementing preventative measures in equine health management. This topic includes research on pathogen-host interactions, the impact of management practices on disease incidence, and the role of genetic and environmental factors in disease susceptibility. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of disease etiology in horses.
HOLLISTER AC, LONGSHORE WA, DEAN BH, STEVENS IM.For the most part, epidemiologic phenomena observed in the outbreak of encephalitis in 1952 accorded with patterns that had been apparent in previous years. Ninety-seven per cent of the 414 laboratory-confirmed cases of western equine and St. Louis encephalitis in humans occurred in the 20 Central Valley counties. The cases of western equine encephalomyelitis in horses were generally scattered over the state. In the Central Valley most of the cases in horses were in animals less than two years of age; elsewhere the incidence was higher in older horses.There were no laboratory-confirmed cases o...
HAMMON WM, REEVES WC.In three cases of encephalitis in humans that occurred in the area where the newly described California virus was isolated from mosquitoes, serological evidence seemed to indict the California virus as the etiological agent. In the case of an infant with very severe disease, the serological evidence was convincing; the evidence was almost as strong in the case of a seven-year-old boy; the results in an adult were equivocal. Inapparent infection in man is quite common as indicated by neutralization tests on the sera of nearly 600 residents of California, but encephalitic manifestations of infec...
Wijnberg ID, Back W, van der Kolk JH.This paper describes a case of unilateral stringhalt present for 18 months in the right hind limb of a 4-year-old Warmblood gelding. The only abnormalities detected by electromyography (EMG) were a prolonged insertion activity, fibrillation potentials, and positive waves at rest and enhanced EMG activity in the right lateral digital extensor muscle on muscle contraction. This was interpreted as denervation and hyperirritability of this muscle. Both similarities and differences with Australian stringhalt could be found. As described for horses suffering from Australian stringhalt, phenytoin sod...
Arndt S, Kilcoyne I, Vaughan B, Dechant JE.To identify etiology, clinical findings, diagnostic results, treatment, and short- and long-term survival and to report factors associated with nonsurvival and survival in horses with peritonitis. Methods: Retrospective study. Methods: Horses (n = 72). Methods: Medical records at William R. Pritchard Veterinary Medical Teaching Hospital from 2007-2017 were reviewed for horses diagnosed with peritonitis. The essential inclusion criterion was a peritoneal nucleated cell count of ≥25 000 cells/μL. Gastrointestinal rupture and cases in which peritonitis occurred after abdominal surgery or cas...
Kirschvink N, Art T, Lekeux P, Roberts C, Gustin P.8-Epi-PGF2alpha, a prostaglandin-like compound generated by oxidative stress, has been shown to be an in vitro bronchoconstrictor in airways from healthy laboratory animals and healthy humans, but it has never been studied in diseased airways. Here, the bronchoconstrictive capacity of 8-epi-PGF2alpha on isolated bronchial rings (BR) of healthy and heaves-affected horses was evaluated by comparing the maximal effect and the potency of 8-epi-PGF2alpha to those of (1) acetylcholine (ACh), (2) its stereoisomer PGF2alpha and (3) its synthetic receptor agonist, U46619. Furthermore, the potential cap...
Chvala S, Nowotny N, Kotzab E, Cain M, van den Hoven R.To evaluate use of the acupuncture meridian test for detection of recent or recently reactivated equine herpesvirus type 1 (EHV-1) infection in horses with decreased performance. Methods: Case-control study. Methods: 40 horses. Methods: Physical and neurologic examinations were performed, and acupuncture points on the bladder meridian were tested for sensitivity reactions in case and control horses. Polymerase chain reaction assays were performed to determine whether EHV-1 or equine herpesvirus type 4 (EHV-4) DNA could be detected in peripheral blood mononuclear cells. Complement fixation (CF)...
Bryant B, Meehan LJ, Roberts V.Standing computed tomographic (CT) examination of the equine guttural pouch frequently reveals deviation of the midline septum. The significance of deviation is currently unknown. The aims of this retrospective, single-centre study were to determine the prevalence of deviation of the midline septum of the guttural pouch and determine whether there was an association between the presence and degree of deviation of the septum, and guttural pouch disease. Case records were reviewed, identifying 95 horses that had undergone a standing, sedated, head CT and guttural pouch endoscopy. The presence, l...
Carlson KL, Chaffin MK, Corapi WV, Snowden KF, Schmitz DG.The starry sky hepatic pattern is an unusual ultrasonographic appearance of equine liver characterized by numerous small, hyperechoic foci, some of which cast an acoustic shadow, distributed randomly throughout the hepatic parenchyma. Our objectives were to describe the signalment, clinical signs, clinicopathological findings, primary disease process, and ultrasonographic findings of horses with this ultrasonographic pattern, as well as determine the associated gross and histologic changes. The starry sky pattern was identified in 18 adult horses of mixed gender and breed. The horses had vario...
Casteleyn C, Cornillie P, Tüllmann V, Van Cruchten S, Van Ginneken C.An Oldenburg colt with wry nose was autopsied after having lived for only 30 min. It presented cyanotic oral mucosae, underdeveloped eyes and a right-sided temporal osseous mass. The applicable nomenclature for the defects is discussed, and the potential etiopathogenesis is explored by describing the normal embryonic development of the affected body parts.
Kretzschmar C, Krüger M.Tumor necrosis factor (TNF) activity in the circulation of several animal species was determined by a bioassay, using the murine cell line L929. In healthy adult cattle, horses, pigs and dogs, species specific differences of systemic TNF activity were visible. In cattle, TNF activity in the circulation increased during growing up from calf to adult animal. In cattle suffering from various diseases, unchanged, elevated, but also reduced systemic TNF activity have proved to possess clinical relevance. Low systemic TNF activity frequently occurs during lethal inflammatory diseases and may be an i...
Campbell TM, Studdert MJ.Severe combined immunodeficiency disease (SCID) in foals is the only known animal model for the autosomal recessive form of primary SCID in man. A major requirement in the treatment of SCID is the maintenance of the patient in a disease free state until definitive therapy can be undertaken. This paper reviews the current status of prophylactic and definitive therapy in man and the horse. Particular emphasis is placed on the methods of reconstitution available, involving foetal tissues and bone marrow.
Vandeplassche M, Simoens P, Bouters R, De Vos N, Verschooten F.In 214 cases of severe dystocia in mares, of which 141 (66 per cent) were Draught horses, deviation of the head and neck, with or without torticollis, malformed head and limbs were found to be the cause of dystocia. No evidence of a genetic lethal factor was found and torticollis was often combined with scoliosis of the head and, frequently, with malformation of one or more limbs. This is considered evidence of a common aetiology and pathogenesis of the syndrome of malformation. The malformations were found to be associated with an increased incidence of caudal and, particularly, transverse pr...
AbouEl Ela NH, El Araby IE, Saleh AA, Abd El-Fattah AH, Hagag NM, Brooks SA, Radwan MA, Kalbfleisch T.Lavender foal syndrome (LFS) is a fatal hereditary condition that is inherited in an autosomal recessive pattern. This detrimental mutation is more common in Arabian foals of Egyptian origin than foals from other bloodlines. Heterozygous horses are carriers of the LFS trait and appear normal, while recessive homozygous foals died shortly after birth due to serious complications. In Egypt, in 2014, an Egyptian foal died after manifestations of neurological signs and abnormal coat colour as LFS signs. Therefore, it is important to identify LFS carriers in the population of Arabian horses in Egyp...
May SA, Hooke RE, Lees P.The presence, in equine synovial fluid, of inhibitors of interleukin-1 (IL-1) activity has been investigated by means of an assay involving IL-1-mediated production of PGE2 by synovial cells. Inhibitors of IL-1 alpha and IL-1 beta were identified in normal synovial fluid and synovial fluid from two horses with early joint disease. Inhibitors of IL-1 alpha were also present in synovial fluid from two horses with long-standing joint disease. However, IL-1 beta inhibitory activity was not present in fluid from the horses with more chronic joint disease. The effect appeared to be specific for IL-1...
Grulke S, Salciccia A, Arévalo Rodríguez JM, Sandersen C, Caudron I, Serteyn D, de la Rebière de Pouyade G.Epiploic foramen entrapment (EFE) of small intestine is a severe cause of strangulating small intestinal obstruction (SSI) with long-term survival seeming lower than for other causes of SSI in horses. Different techniques via laparoscopy or laparotomy for epiploic foramen (EF) closure have been developed. This study describes a technique of peroperative mesh closure of the EF in clinical cases and their long-term follow up. In the study period of 5.5 years, 36 horses were admitted to the clinic with EFE. Of these, 17 horses had peroperative mesh closure, with resection anastomosis in 4 cases a...
Woods AC, Chesney AM.A filterable agent has been obtained from the humors and tissues of the eyes of horses suffering from active periodic ophthalmia. The intra-vitreous injection of this filtrate produced in normal horses the same clinical and pathological picture observed in the natural disease. This filtrate injected into rabbits produced a different clinical picture, but the essential pathological lesions closely resembled those found in horses. After passage of the filterable agent through six generations of rabbits, it again produced the clinical and pathological picture of the natural disease when injected ...
Asquith RL, Edds GT, Aller WW, Bortell R.Twelve clinically normal Shetland ponies were allocated to one of four treatment groups. Aflatoxin B1 was administered at the dosage level of 2 mg/kg of body weight to group A, 1 mg/kg to group B, and 0.5 mg/kg to group C; a placebo was given to group D (controls). Plasma samples were assayed at 4-hour intervals for iditol dehydrogenase (ID) (sorbitol dehydrogenase) concentrations as an indicator of hepatic damage. One of the ponies in group A died 68 hours after dosing; another pony in group A died 76 hours after dosing. All other animals survived the experiment. The means of peak ID values w...
Pozio E, Celano GV, Sacchi L, Pavia C, Rossi P, Tamburrini A, Corona S, La Rosa G.Epidemiological investigations conducted during 10 trichinellosis outbreaks between 1975 and 1994 showed that horse-meat was the probable source of infection. Though hundreds of thousands of horses have been examined at abattoirs in America and Europe to detect Trichinella infection by artificial digestion or trichinelloscopy, an infected horse has never been detected during routine analysis, which consists of examining 1 g of tissue muscle from the diaphragm. In November 1996, a naturally infected horse imported from Romania was detected in Southern Italy. The parasite was identified as Trich...
Moll HD, Schumacher J.A 2-year-old Tennessee Walking Horse colt was admitted for evaluation of signs of abdominal pain, inappetence, and constipation of 5 days' duration. Two days prior to the onset of signs, the owner had cut the sacrococcygeal muscles as part of a tail-setting procedure. On examination, the horse was febrile and lethargic, and intestinal sounds were not heard on auscultation. Results of peritoneal fluid analysis were indicative of peritonitis. The horse continued to deteriorate and died despite treatment with antimicrobials, flunixin meglumine, and balanced electrolyte solution. At necropsy, the ...
van Foreest AW, Wiemer P.Periapical disorders in horses can be treated by resection of the apex. The indications, contraindications, diagnosis, treatment and complications of the intervention are discussed. Four case reports of horses in which apicoectomy with retrograde endodontic treatment was performed are reviewed.
Page AE, Stills HF, Horohov DW.Multiple hypotheses into the age-based susceptibility of animals to Lawsonia intracellularis exist, including the decline of passively acquired antibodies. Objective: To determine whether the decline in passively acquired antibodies in horses is responsible for the age predilection of equine proliferative enteropathy (EPE). Additional objectives included examination of various risk factors for the development of EPE as well as the determination of naturally occurring attack rates for clinical and subclinical EPE. Methods: Prospective, multifarm field study. Methods: A total of 369 mare and f...
Nollet H, Deprez P.Since riders nowadays are expecting the highest level of performance from their horses, muscular disorders therefore represent a major problem for the equine athlete. A lot of research has been done to identify muscular disorders and their etiopathogenesis. Both acquired and inherited forms of muscle diseases have been described. In this review only the latter forms will be mentioned. Major signs of all muscle disorders are muscular stiffness, cramping or pain, muscular fasciculations, muscular atrophy and exercise intolerance. Muscle biopsies can help to identify the cause of rhabdomyolysis o...
Hildebrandt L, Jäger K, Snyder A, Sobiraj A.The case report describes a narrowing of the spinal canal in the lumbar and sacroiliac regions with entailing acute recumbency in a nearterm 17-year-old Welsh B Pony mare. The reason for recumbency was metastases of a malignant melanoma in the spinal canal of the lumbo-sacral region, where the tumour had invaded the dura mater and applied severe pression on the spinal cord over a length of 10 cm. Clinical findings, laboratory diagnostics, pathological-anatomical and histopathological findings are presented.
Tobin T, Watt DS, Kwiatkowski S, Tai HH, Blake JW, McDonald J, Prange CA, Wie S.We have introduced large scale non-isotopic immunoassay testing into pre- and post-race drug testing in racehorses. The technologies utilized are Particle Concentration Fluorescence Immuno Assay (PCFIA) and the one-step Enzyme Linked Immuno Sorbent Assay (ELISA). These technologies are rapid, inexpensive, and highly effective. On introduction into post-race testing in the Western United States, these ELISA tests exposed several previously undetected patterns of drug abuse. The drugs detected were buprenorphine, oxymorphone, mazindol, sufentanil and cocaine. This led to the suspension of a larg...
Routledge NB, Harris RC, Harris PA, Naylor JR, Roberts CA.The variation over 24 h of plasma glutamine concentration in nonexercising horses was studied in 3 Thoroughbreds (TB) fed at 1600 h and 0700 h. This indicated a small but regular change associated with feeding. Starting at a mean of 482 mumol/l at 1600 h the concentration increased to 522 mumol/l at 2000 h, falling to 476 mumol/l at 1600 h and increasing again to 525 mumol/l at 2000 h. 'Normal' values were established in 19 part-bred TB horses, lacking clinical signs or remarkable pathology and in light training, by sampling weekly at 1000 h over a 10 week period. The mean concentration was 49...
Bennett D.The gross and histological features of multiple bone infection in two foals are described. In both cases the lesions were confined to the region of the growth plate. Bone and, in some cases, growth plate cartilage destruction has occurred associated with an extensive inflammatory cell infiltration. The significance of the pathological observation is discussed in relation to the pathogenesis of bone infection in the foal.
Dewes HF, Lowe MD.Events leading to the deaths of two fillies at pasture are described. Pasture hay containing the flowering stages of Senecio jacobea (ragwort) had been fed three to four months earlier. Paddocks were subdivided with posts and rails treated with copper chrome arsenate. Six horses on the property chewed rails spasmodically. Both fillies presented with haemoglobinurea. Values in liver of 83 mg Cu kg and kidney 35 mg Cu kg wet weight and serum 1.4 mg Cu/l together with histophathology of seneciosis support a sequence of ragwort poisoning followed by copper accumulation in liver and kidney terminat...
Johns I, McParland T, Mair T.Pleural effusion (PE) is reported to occur most commonly secondary to bacterial pneumonia or lung abscesses, with neoplastic effusions contributing the minority of cases. The majority of these reports originate from America and Australia, where long distance transport of horses, a recognised risk factor, appears to occur more frequently. Anecdotally, neoplastic PE is more commonly diagnosed in the UK. Objective: To describe the causes of PE in horses resident in the UK, and to identify potential markers that can help differentiate between infectious and neoplastic causes of PE. Methods: Retros...
Furr MO.Neurologic disease of foals is a diagnostic and therapeutic challenge for veterinarians. Disease conditions such as neonatal encephalopathy are seen as well as developmental and congenital defects, bacterial infections, and trauma. Neonatal encephalopathy can be considered a "syndrome" with a variety of causes resulting in a similar clinical presentation. These causes can be categorized as maladaptation, hypoxic/ischemic encephalopathy, and metabolic abnormalities, all leading to signs of cerebral and brainstem disease. Spinal cord signs may occasionally be seen, but these signs are usually ov...
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 ...
Dyson S.The difficulties associated with the interpretation of the results of regional and intra-articular anaesthesia are discussed with reference to eight lame horses. The clinical and radiographic features of each horse are described, together with the results of anaesthesia. One horse had clinical and radiographic signs consistent with navicular disease but it was not possible to relieve the lameness. Two horses had fractures of bones within the foot but lameness was not improved by palmar (abaxial sesamoid) nerve blocks. One horse had more than one cause of lameness. Four horses had joint patholo...
Wilson CS, Brookes VJ, Hughes KJ, Trope GD, Ip H, Gunn AJ.In human subjects, arytenoid chondritis can be caused by chemical trauma of mucosa attributable to gastro-oesophageal reflux. Although a similar process may be involved in the aetiopathogenesis of arytenoid chondritis in horses, the oesophageal lumen pH in this species is poorly understood. Objective: To determine if gastro-oesophageal reflux occurs in horses by characterising oesophageal lumen pH. Methods: Blinded, randomised, placebo-controlled, crossover, experimental study. Methods: Luminal oesophageal pH in six yearling horses was recorded over four 24 h periods using an ambulatory pH rec...
