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.
Kikuchi N, Iguchi I, Hiramune T.A survey of K. pneumoniae was performed on cervical swabs, feces and nasal swabs of mares and on samples from the genital tract of stallions from 1980 to 1986 in south-western Hokkaido, Japan. K1 was the predominant type (79 of 88, 89.8%) in the metritis cases due to K. pneumoniae in mares of racing breeds. The same type was isolated from semen and swabs of the fossa glandis of 6 of 20 (30.0%) of the stallions of racing breeds. Heavily encapsulated and less heavily encapsulated K1 strains were isolated from the stallions. Mares bred to stallions carrying heavily encapsulated strains developed ...
Kuttler KL, Zaugg JL, Gipson CA.The therapeutic efficacies of imidocarb and parvaquone were tested against Babesia equi of European origin in carrier horses and for induced acute infections in splenectomized ponies. Imidocarb, at a dosage of 4 mg/kg of body weight, given IM at 72-hour intervals 4 times, was ineffective in eliminating B equi-carrier infection in 9 mature geldings. A single IM administration of 4 mg/kg was not therapeutic in acutely infected splenectomized ponies. When given at 3 different dosages and treatment schedules, parvaquone was ineffective in clearing carrier infection. Parvaquone given IM once at a d...
Johnston JK, Neely DP, Latterman SA.A 4.5-month-old Standard-bred filly was referred for evaluation of pigmenturia. Initially, the pigmenturia had resolved with the administration of antibiotics, only to recur after their withdrawal. A dark red urine sample contained numerous RBC, WBC, and gram-negative rods (Escherichia coli). Ultrasonography revealed the right kidney to be large, with multiple cystic structures and a dilated renal pelvis and calices. Cystoscopy revealed a large blood clot within the bladder and urine coming from the left ureteral opening. Urine was not observed coming from the right ureter. It was suspected th...
Clark ES, Reef VB, Sweeney CR, Lichtensteiger C.Aortic insufficiency was suspected in a thin 1-year-old colt with a grade IV/V decrescendo holodiastolic murmur and a bounding arterial pulse. Echocardiographic findings (diastolic fluttering of the septal leaflet of the mitral valve, left ventricular volume overload, and incomplete aortic valve closure) were diagnostic for aortic valve insufficiency. Moderately thick fibrotic aortic valve leaflets were found at necropsy. Fenestrations were found in the aortic and pulmonic valve cusps. Congenital valvular disease may have led to aortic valvular insufficiency in this horse.
Rugh KS, Garner HE, Hatfield DG, Miramonti JR.The response of coronary collaterals in nine ponies subjected to repeated reversible occlusions (2 min duration, 30 min interval) of the left anterior descending coronary artery was studied at rest. Each pony was instrumented with a Doppler flowmeter and hydraulic cuff occluder around the left anterior descending coronary artery, left ventricular subendocardial sonomicrometers, and a left ventricular micromanometer. Initial occlusions increased end diastolic myocardial segment length by 3% and decreased segment systolic shortening, stroke work, and velocity of shortening by 103%, 95%, and 79% ...
Perdrizet JA, Callihan DR, Rebhun WC, Shin SJ.The clinical course and successful therapeutic management of a horse with malignant edema caused by Clostridium septicum is described. This is believed to be the first report of a horse surviving malignant edema caused by C. septicum. A discussion of this disease syndrome, including etiology, pathogenesis, clinical signs, therapy, and diagnostic methods is presented.
Johnston JK, Morris DD.Sixty-eight horses with colic caused by small intestinal disease were allotted into 2 groups of 34 on the basis of recorded findings during exploratory celiotomy, necropsy, or response to medical treatment alone. Signalment, history, physical examination findings, and laboratory findings were compared between the group of horses with small intestinal obstruction and the group with duodenitis/proximal jejunitis. A significantly greater proportion of horses with duodenitis/proximal jejunitis were older than 2 years old (P less than 0.05). Differences in sex or breed distribution, or in seasonali...
Abid HN, Walter PA, Litchfield H.A 6-year-old Quarter Horse gelding was examined because it had a sharply circumscribed, firm, brown-black, roughly spherical dermal nodule at the right tuber ischii. After it was excised, the lesion did not recur. Microscopically, the dermis of the excised specimen had multiple pyogranulomas, many of which contained thick-walled, dark brown fungal elements, some with internal septation compatible with chromomycotic fungi. Chromomycosis is a rare skin disease in the horse. It may be included in the differential diagnoses of nodular and/or pigmented skin lesions that include melanoma, pyogranulo...
Memon MA, McClure JJ, Usenik EA.An 8-year-old Quarter Horse stallion was admitted with a swelling involving the prepuce, dorsal part of the scrotum, and root of the penis. The swelling was first noticed 10 days after breeding, with no evidence that it had resulted from a kick by the mare. The penis was retracted into the prepuce, except for a 10- to 15-cm protrusion of the glans penis. Treatment included warm hydrotherapy, massage, stockinette compression, antidiuretics, antibiotics, penile support, and exercise, without success. At necropsy, a massive preputial hematoma was found extending forward from the root of the penis...
Hoffmann WE, Baker G, Rieser S, Dorner JL.Effects of induced cholestasis and hepatocellular necrosis and of fasting on serum biochemical constituents including bile acids, IgA, bilirubin, alkaline phosphatase, gamma-glutamyltransferase (GGT), arginase, and the clearance of sodium sulfobromophthalein were studied in 4 groups of equids. The reference value for serum bile acids, as determined by an enzymatic colorimetric procedure for horses and ponies was 5.94 +/- 2.72 mumol/L, there being no statistical difference for horses and ponies. Sample collection at time of feeding had no effect on serum bile acid concentration. Seemingly, seru...
O'Callaghan MW, Pascoe JR, Tyler WS, Mason DK.Lungs from 19 Thoroughbred racehorses with a history of exercise-induced pulmonary haemorrhage (EIPH) were studied using several forms of microscopy. Light microscopy of paraffin sections revealed three lesions in the caudodorsal region of the lungs from each horse. These correspond with the location of blue to brown stains seen at necropsy. These lesions include sequelae of bronchiolitis, hemosiderophages and increased connective tissue. Much of each of the lungs appeared normal, especially the more cranial or ventral portions. Foci of eosinophil infiltration were found in seven of the 19 lun...
Matthews SM, Joysey VC.Fifteen equine leucocyte antigens were defined by absorption and titration analysis of alloantisera obtained by natural sensitisation through pregnancy and by planned experimental immunisation. Definitive sera were tested on the cells of 90 unrelated horses and members of eight equine families. The family data suggested that 13 specificities were coded by a single locus (first locus) and one specificity (Eq 14) was coded by a second linked locus. The remaining specificity (Eq 7) was controlled by a third locus unlinked to the first or second loci. Tests on the cells of unrelated horses showed ...
O'Callaghan MW, Pascoe JR, Tyler WS, Mason DK.This paper reviews a series of clinical, post mortem and imaging studies on exercise-induced pulmonary haemorrhage (EIPH) performed on 26 Thoroughbred racehorses. Post mortem techniques included routine gross, subgross and histological examination; coloured latex perfusions of pulmonary and bronchial circulations; and microradiography and computerised tomography scans of lungs with contrast injected vasculature. The major lesions were multiple, separate and coalescing foci of moderately proliferative small airway disease accompanied by intense neovascularisation of the bronchial circulation. A...
Clarke AF.This paper reviews the environmental and host factors which interact to affect the incidence and severity of episodes of respiratory disease in stabled horses. The folly of accepting housing criteria and management practices for the horse, based on direct extrapolations from intensive housing of meat producing animals, is discussed. The factors which affect air hygiene and physical environment of stables are considered in terms of short-term athletic performance and long-term welfare.
Watson ED, Stokes CR, Bourne FJ.Both random and directional migration of blood neutrophils from 9 mares susceptible to persistent endometritis were significantly less (p less than 0.05) than neutrophils from 8 resistant mares. Serum from susceptible mares had significantly more (p less than 0.01) chemotactic activity than serum from resistant mares. Although phagocytosis of yeast blastospores by blood neutrophils from 4 resistant and 3 susceptible mares was similar, uterine neutrophils from susceptible mares were significantly worse (p less than 0.01) at phagocytosis than uterine neutrophils from resistant mares. Uterine was...
Gadsby PM, Peterson J, Foote N, Greenwood C, Thomson AJ.Magnetic-circular-dichroism (m.c.d.) spectra over the wavelength range 300-2000 nm at room temperature and at 4.2K of horse heart cytochrome c are reported at a series of pH values between 7.8 and 11.0, encompassing the alkaline transition. The effect of glassing agents on the e.p.r. spectrum at various pH values is also reported. Comparison of these results with spectra obtained for the n-butylamine adduct of soybean leghaemoglobin support the hypothesis that lysine is the sixth ligand in the alkaline form of horse heart cytochrome c. The m.c.d. and e.p.r. spectra of horse heart cytochrome c ...
Rollinson J, Taylor FG, Chesney J.Six cases of accidental salinomycin poisoning in horses are described. The horses were fed a contaminated ration and presented clinical signs which were extremely varied in nature and severity. However, the range of signs, including anorexia, colic, weakness and ataxia bore similarities to those described in horses poisoned with the related ionophore monensin. Other similarities became apparent in serum biochemical profiles of the clinical cases. Although ionophore toxicity is rarely reported in horses they appear to be particularly susceptible, and it should therefore be considered as a diffe...
Kiper ML, MacAllister C, Qualls C.A cranial mesenteric arterial aneurysm with fistulous tracts to the cecum and ileum was discovered in a Missouri Fox Trotter stallion. The principal clinical sign was hematochezia, observed at 7- and 10-day intervals. The lesion may have been attributable to arteritis caused by fourth-stage larvae of Strongylus vulgaris.
Menzies-Gow NJ, Young NJ.Enterococcus faecium, a major cause of potentially life-threatening hospital-acquired human infections, can be resistant to several antimicrobials, such that streptogramin quinupristin-dalfopristin (Q/D) is one of the few antibiotics still effective. Consequently use of the streptogramin virginiamycin as an animal growth promoter was banned in the EU in 1999 as some believed this contributed to the emergence of Q/D resistant E. faecium. Virginiamycin is advocated for preventing equine pasture-associated laminitis, but its effect on equine faecal bacterial Q/D resistance has not been determined...
Linke RP, Trautwein G.Tumorous amyloid deposits in the nasal mucosa of two horses differed from generalized AA-amyloidosis with respect to clinical features, organ distribution, and resistance to KMnO4 treatment. Using a panel of antibodies directed against different human amyloid fibril proteins and employing the peroxidase-anti-peroxidase (PAP) technique, we showed the described equine amyloid to be A lambda-type, as demonstrated by immunohistochemical cross-reactivity. Consequently, we identified a second amyloid class in horses and showed that immunoglobulin light-chain-derived amyloid may also be present in an...
Divers TJ, George LW, George JW.Signs of acute hemolytic anemia developed in 4 adult horses from 2 Georgia farms 3 to 4 days after the ingestion of wilted leaves from cut red maple trees (Acer rubrum). Clinical findings included weakness, polypnea, tachycardia, depression, icterus, cyanosis, and brownish discoloration of the blood and urine. Blood changes included methemoglobinemia, free plasma hemoglobin, decreased pcv, and Heinz bodies in erythrocytes. These findings plus hemoglobinuria suggested intravascular hemolysis. Three of the 4 horses diet 5 to 7 days after ingestion of the leaves. Gross pathologic changes included...
Christen G, Precht C, van der Kolk J, Fouché N, Gerber V.Endocrinopathic laminitis occurs as a consequence of hormonal derangements like pituitary pars intermedia dysfunction (PPID). The objective of the present study was to assess the occurrence of radiographic changes associated with chronic laminitis in elderly, clinically sound horses. Fifty-one horses were included in the study. Horses were assigned to different age groups, in groups according to their BCS and CNS as well as to groups with different ACTH concentrations in order to assess their risk of chronic laminitis (reported as odds ratios (OR) and confidence intervals (CI)). Horses assigne...
Irvine CH, Sutton P, Turner JE, Mennick PE.Plasma progesterone concentrations were measured in 179 mares bled on alternate days commencing with a positive pregnancy diagnosis on Days 17 to 18 after ovulation and concluding on Days 42 to 45. During this period 17 mares (10 per cent) lost their pregnancies, 11 before Day 25. In 15 mares the timing of the pregnancy loss could be determined with adequate accuracy; in only one did a decline in progesterone precede the loss. Thus pregnancy loss between Days 17 and 42 was rarely caused by a fall in plasma progesterone.
Wheeldon EB, Greig WA.The history, clinical signs and post mortem findings in a case of Globidium leuckarti infection in a horse with chronic diarrhoea are described. The limited literature concerning this infection is reviewed, with particular reference to pathogenicity.
Trout DR, Hornof WJ, Linford RL, O'Brien TR.Scintigraphy was used to evaluate digital circulation at 24 h intervals in 11 control horses and in nine horses affected with acute laminitis created by administration of a high-starch ration. Following intra-arterial injection of technetium-99m macroaggregated albumin into the brachiocephalic trunk, static images were acquired of the right front foot. Dynamic radionuclide angiograms and static blood pool images were also obtained after jugular vein injection of technetium-99m diethylenetriamine pentaacetic acid. These procedures were performed on standing horses, using either minimal or no tr...
Huxtable CR, Chapman HM, Main DC, Vass D, Pearse BH, Hilbert BJ.A severe paretic syndrome accompanied by intense neuronal lipofuscinosis is described in sheep and horses exposed to Trachyandra divaricata. This is a newly recognised toxic hazard for grazing livestock in the coastal region of the south west of Western Australia. Animals appear to become affected over a period of weeks when summer conditions induce a scarcity of alternative feed. The disease is discussed in relation to its recent documentation in South Africa where the plant is indigenous.
Conrado FO, Iapoce N, Batista-Linhares M, Lopez S, Matthews MH, McKinney CA, Rothacker C.An 18-year-old, grey, Thoroughbred Cross gelding was referred to the Cummings School of Veterinary Medicine at Tufts University following a 3-week history of low-grade fever of unknown origin, distal limb swelling, and weight loss. Clinical examination identified a few black, round, smooth nodules along the ventral aspect of the proximal tail. Transabdominal ultrasound showed a markedly enlarged heterogenous spleen, hyperechoic liver nodules, and evidence of peritonitis with fibrin deposition. A mature neutrophilia was noted on complete blood count with variable numbers of phagocytized granule...
Perryman LE.Primary immunodeficiency disorders are genetically determined failures of immune defense that increase susceptibility to infectious agents. This article reviews the salient features of equine primary immunodeficiency disorders, summarizes the molecular mechanisms of each disorder, and updates information that facilitates diagnosis and management of affected horses. The central theme is to encourage clinicians to ask, "I wonder if this horse has an underlying primary immunodeficiency disorder?" when caring for horses suffering from chronic and recurring infections and responding poorly to stand...
Robinson NE, Scott JB, Dabney JM, Jones GA.Digital vascular pressures, blood flow, and vascular resistances were measured in 11 control ponies and in 8 animals (7 ponies and 1 horse) affected with laminitis created by feeding a high starch ration. Animals with laminitis had increased digital blood flow, increased arterial, small vein, and large vein pressures, and decreased vascular resistances. Comparison of digital lymph flow rates and protein concentrations in animals with laminitis and control animals revealed no differences. Digital vascular responses of the 2 groups to acetylcholine, epinephrine, histamine, or serotonin also did ...
Dixon JB, Savage M, Wattret A, Taylor P, Ross G, Carter SD, Kelly DF, Haywood S, Phythian C, Macintyre AR, Bell SC, Knottenbelt DC, Green JR.A condition resembling acquired immunodeficiency with anemia has been described in British Fell pony foals. The pathogenesis is unknown. The present study involved 322 foals of which 164 were of Fell breed and 12 were affected. Discriminant and multiple regression analyses were used to test the results of all clinical pathology parameters from these foals for statistical association with (1) breed origin and (2) presence of disease. Only hematocrit associated significantly with presence of disease. However, significant associations were found with Fell breed origin, including serum albumin con...
Holý O, Matousková I, Holý V, Koukalová D, Chmelar D.Cronobacter spp. belongs to the family Enterobacteriaceae. It is a motile (peritricha) Gram-negative non-spore forming bacterium. At present, Enterobacter sakazakii is reported as a Cronobacter spp. species with 16 biogroups. It is a ubiquitous organism whose isolation used to be associated with a contaminated powdered infant formula and feed for neonates and infants. Information about the Cronobacter spp. species incidence in the environment, its potential dissemination and its vectors, is very limited. The authors have documented incidence of Cronobacter spp. in the nostril mucous membrane o...