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.
Schlacher C, Peham C, Licka T, Schobesberger H.Mechanical properties of the equine back are the bases for realistic modelling of the back, which is recognised as an important step towards improved understanding of the pathogenesis of equine back conditions. Objective: The stiffness of the equine back depends on the direction of the applied force and on the position of the spine. Methods: Fourteen dissected spines were tested in a tensile testing machine. In 3 different positions, simulating dorsoventral, laterolateral and dorsoventral-30 degree rotated movement, force was applied on the dorsal spinous process of T12 to reach an excursion o...
Ensink JM, Voermans M, Bartels JH, Passon-Vastenburgen MH, Loeb E.A 14-year-old Haflinger mare was presented with a wound on the right metatarsus which it had sustained 3 years earlier. The wound had never completely healed but had only recently become a problem. Over a period of several months, the wound became larger, produced a lot of exudate, and the horse became lame on the affected limb. Clinical examination and radiographs failed to reveal the cause of the deterioration. Histological evaluation of tissue removed during debridement of the wound revealed squamous cell carcinoma. Because the tumour had already invaded the bone, the prognosis was unfavour...
Peham C, Schobesberger H.Knowledge of load effects is crucial for the understanding of the aetiology and pathogenesis of equine back problems. Objective: To investigate different load scenarios of the equine back, such as being ridden or increased muscle tone, using biomechanical simulations. Methods: Kinetic and kinematic data of 15 sound horses and the electromyelograph of their long back muscles were recorded. A biomechanical simulation model was used for simulations under different biomechanical scenarios (ridden/unridden, localised increased stiffness) using ADAMS. Results: The vertical forces acting through a ri...
Arai K, Misumi K, Carter SD, Shinbara S, Fujiki M, Sakamoto H.Cartilage oligomeric matrix protein (COMP) is abundant within cartilage; its turnover and/or degradation have been investigated in various equine joint diseases and it has been suggested that COMP fragmentation might be useful for monitoring such conditions. Objective: To determine whether COMP metabolism is compromised in equine osteoarthritis (OA) and whether COMP degradation is a useful joint marker representing cartilage destruction. Objective: A monoclonal antibody (mAb) with a higher affinity for degraded COMP allows discrimination of diseased joints by quantifying COMP levels and fragme...
Jackson BF, Lonnell C, Verheyen KL, Dyson P, Pfeiffer DU, Price JS.Dorsal metacarpal disease (DMD) is a common problem in 2-year-old racehorses and results in loss of a significant number of days from training. Biochemical markers of bone cell activity measured early in the training season could have value for identifying 2-year-old Thoroughbred racehorses that develop DMD. Objective: To determine the association between serum concentrations of osteocalcin, the carboxyterminal propeptide of type I collagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP) measured early in the training season and the risk of DMD. Methods: Blood...
Thomas GW, Bell SC, Carter SD.Fell pony foals are affected by a congenital fatal disease that leads to profound anaemia and immunodeficiency. Previous studies comparing healthy and affected foals have shown normal T-cell populations, but a severe B-lymphopenia. Objective: To measure the levels of individual immunoglobulin subisotypes in normal and affected Fell ponies and correlate these levels with the number of peripheral B-lymphocytes. Methods: Serum levels of individual immunoglobulin subisotypes were measured by ELISA and correlated with the number of peripheral B-lymphocytes (measured by flow cytometry). Results: Aff...
Ekman S, Skiöldebrand E, Heinegård D, Hultenby K.One of the most common causes of lameness in racehorses is osteoarthritis (OA). Pathogenesis is not clear and pathological processes of the different joint tissues interact in often progressive events. The interface between cartilage and newly synthesised bone has been shown to be particularly enriched in bone sialoprotein (BSP), a cell-binding matrix protein. Objective: To establish whether changes in the concentration of BSP may serve as a marker for early biochemical changes of the subchondral bone. Methods: Articular cartilage, cartilage/bone interface and subchondral bone of the proximal ...
Seki Y, Seimiya YM, Yaegashi G, Kumagai S, Sentsui H, Nishimori T, Ishihara R.During the period from 2001 to the following year, progenital diseases had been epidemic among the draft stallions and mares pastured together in Iwate Prefecture, the northeastern district of Japan. A stallion and 8 of 31 mares were affected in 2001, and 1 of 2 stallions and 10 of 36 mares in 2002. The clinical symptoms consisted of the formation of papules, pustules, ulcers and scabs on the progenital skin and mucosa in stallions and mares. In 2002, Equine herpesvirus 3 (EHV3) was isolated from 2 mares and the glycoprotein G gene of the virus detected from a stallion and 4 mares by polymeras...
Grewal JS, McClure SR, Booth LC, Evans RB, Caston SS.To characterize the normal ultrasonographic appearance of the podotrochlear apparatus in horses by use of standardized measurements and identify soft tissue changes associated with navicular syndrome. Methods: Prospective study. Methods: 7 clinically normal horses and 28 horses with navicular syndrome. Methods: The feasibility of identifying and measuring the soft tissue structures of the podotrochlear apparatus ultrasonographically via the transcuneal approach was assessed in 2 additional horses without navicular syndrome; both horses were euthanatized, and the structures identified ultrasono...
Hilbe M, Guscetti F, Wunderlin S, Ehrensperger F.Equine and feline dysautonomias are characterized histopathologically by degenerating neurons with chromatolysis, pyknotic and sometimes eccentric nuclei, and loss of Nissl substance in the peripheral autonomic ganglia. Because it may be difficult to distinguish pathological from post-mortem changes in affected ganglia by histopathological examination, synaptophysin was evaluated as an immunohistochemical marker. Degenerating neurons showed strong intracytoplasmic labelling indicating abnormal accumulation of synaptophysin. It was concluded that synaptophysin immunohistochemistry is a helpful ...
Frank N, Sojka J, Messer NT.Hypothyroidism is the most common type of thyroid gland dysfunction reported in horses. Primary, secondary, and tertiary causes of hypothyroidism are discussed. Equine hypothyroidism remains a controversial endocrine disorder because extrathyroidal factors, including the administration of drugs and systemic diseases, affect serum triiodothyronine (T3) and thyroxine (T3) concentrations in horses. Accurate diagnosis of hypothyroidism therefore requires assessment of the hypothalamic-pituitary-thyroid axis. Diagnostic procedures for evaluating thyroid gland function are outlined and results of st...
Wood JL, Newton JR, Chanter N, Mumford JA.Respiratory disease is important in horses, particularly in young Thoroughbred racehorses, and inflammation that is detected in the trachea and bronchi (termed inflammatory airway disease [IAD]) is more significant in this population in terms of impact and frequency than other presentations of respiratory disease. IAD, which is characterized by neutrophilic inflammation, mild clinical signs, and accumulation of mucus in the trachea, may be multifactorial, possibly involving infections and environmental and immunological factors, and its etiology remains unclear. This 3-year longitudinal study ...
Foley JE, Spier SJ, Mihalyi J, Drazenovich N, Leutenegger CM.To characterize isolates of Corynebacterium pseudotuberculosis from horses, cattle, and sheep in Colorado, Kentucky, Utah, and California in samples collected during perceived epidemics of infection (increased numbers of cases identified) in 2002 and 2003, and determine how closely isolates were related and their possible source. Methods: 54 isolates of C pseudotuberculosis from 49 horses, 4 cattle, and 1 sheep. Methods: Random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) assay, PCR assay for the gene encoding the phospholipase D (PLD) toxin, biochemical analyses, and tests...
Hosaka Y, Teraoka H, Yamamoto E, Ueda H, Takehana K.The aim of the present study was to clarify the presence and determine the role of apoptosis in the degenerative process of the superficial digital flexor tendon (SDFT) in the horse. Samples were obtained from normal and inflamed SDFTs of horses. To detect apoptosis and to identify apoptotic cells, the samples were subjected to immunohistochemical labelling and Western blot analysis. Although a large number of cells in degenerate areas showed positive reactions with caspase-3 and single stranded DNA antibodies, cells in normal tendon samples showed very weak reactions. Excessive apoptosis was ...
De Cock HE, Affolter VK, Wisner ER, Ferraro GL, MacLachlan NJ.A condition characterized by progressive swelling, hyperkeratosis, and fibrosis of the distal limbs has been recognized in Shire, Clydesdale, and Belgian draft horses. This chronic progressive disease starts at an early age, progresses throughout the life of the horse, and often ends in disfigurement and disability of the limbs that inevitably leads to the horse's premature death. This study was undertaken to better characterize this disease. Results: Six affected horses were donated for diagnostic workup. A detailed clinical, radiologic, gross, and histologic description is given in this repo...
Oxford JS, Lambkin R, Sefton A, Daniels R, Elliot A, Brown R, Gill D.The Great Influenza Pandemic of 1918-1919 was a cataclysmic outbreak of infection wherein over 50 million people died worldwide within 18 months. The question of the origin is important because most influenza surveillance at present is focussed on S.E. Asia. Two later pandemic viruses in 1957 and 1968 arose in this region. However we present evidence that early outbreaks of a new disease with rapid onset and spreadability, high mortality in young soldiers in the British base camp at Etaples in Northern France in the winter of 1917 is, at least to date, the most likely focus of origin of the pa...
Vandenabeele SI, White SD, Affolter VK, Kass PH, Ihrke PJ.Twenty horses with pemphigus foliaceus were seen over a period of 15 years in a veterinary medical teaching hospital. Breeds seen were seven quarterhorses, five thoroughbreds, three cross-bred horses, two Arabians and one of each of the following: standardbred, Tennessee walker and warmblood. There was no breed, age or sex predisposition. Nine were mares, ten were geldings and one was a stallion. Ages ranged from 2.5 months to 25 years, with a mean of 8.6 years. Sixteen (80%) of the pemphigus foliaceus horses first exhibited signs between September and February. There was a statistically signi...
Malisauskas M, Ostman J, Darinskas A, Zamotin V, Liutkevicius E, Lundgren E, Morozova-Roche LA.In amyloid diseases, it is not evident which protein aggregates induce cell death via specific molecular mechanisms and which cause damage because of their mass accumulation and mechanical properties. We showed that equine lysozyme assembles into soluble amyloid oligomers and protofilaments at pH 2.0 and 4.5, 57 degrees C. They bind thioflavin-T and Congo red similar to common amyloid structures, and their morphology was monitored by atomic force microscopy. Molecular volume evaluation from microscopic measurements allowed us to identify distinct types of oligomers, ranging from tetramer to oc...
Dunkel B, Shokek AB, Wilkins PA.A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.
Chan CP, Wan TS, Watkins KL, Pelsers MM, Van der Voort D, Tang FP, Lam KH, Mill J, Yuan Y, Lehmann M, Hempel A, Sanderson JE, Glatz JF, Renneberg R.Fatty acid-binding protein (FABP) holds promise for early detection of tissue injury. This small protein (15kD) appears earlier in the blood than large proteins after cell damage. Combined its characteristics of high concentration tissue contents and low normal plasma values provide the possibility of a rapid rise above the respective reference values, and thus an early indication of the appearance of tissue injury. A general review was presented on the current status of different types of FABP for the detection of tissue injury in patients with myocardial injury, brain injury and also in athl...
Seltenhammer MH, Heere-Ress E, Brandt S, Druml T, Jansen B, Pehamberger H, Niebauer GW.Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathol...
Tydén E, Olsén L, Tallkvist J, Larsson P, Tjälve H.The intestinal enterocytes provide the initial site for cytochrome P450 (CYP)-mediated metabolism of orally absorbed xenobiotics. In man and some animal species, the CYP3A subfamily is highly expressed in the intestines and considered to be important in the first-pass metabolism of drugs and other xenobiotics. The aim of the present study was to investigate the mRNA expression, immunohistochemical localization and catalytic activity of CYP3A in the intestines of horse. Real-time RT-PCR analyses showed that the highest CYP3A mRNA expression was present in the duodenum with a decreasing level to...
Muñoz E, Leiva M, Naranjo C, Peña T.A 4-year-old Andalusian horse was presented for examination following a 3-month history of exophthalmos of the right eye and a soft swelling of the right supraorbital fossa noted after blunt head trauma. Ultrasonographic examination of the swelling showed an anecogenic mass of 5 cm in diameter involving the retrobulbar space. Centesis of the mass through the supraorbital fossa was performed and yielded a serous fluid with 7.2 g/dL of total protein and density of 1040. No cells were seen in the sample. A tentative diagnosis of cyst was made. The cyst was surgically removed and the definitive hi...
Trotter GW, McKinnon AO.Reproductive failure in mares can present a challenge to the attending veterinarian. Although many causes of failure to conceive or to carry to term may be easy to diagnose and treat effectively, others may be difficult. In some cases, more than one problem will be present, and both medical therapy and surgical intervention will be required to achieve a successful outcome. Pneumovagina and its sequelae remain a common cause of reproductive failure in mares. Depending on the case involved, different surgical techniques may be required to correct the problem.
Aleman M, Madigan JE, Williams DC, Holliday TA.Reports of the use of brainstem auditory evoked response (BAER) as a diagnostic modality in foals have been limited. Objective: To describe BAER findings and associated causes of hearing loss in foals. Methods: Study group 18 foals (15 neonatal, 3 nonneonatal), control group (5 neonatal foals). Methods: Retrospective. BAER records from the Clinical Neurophysiology Laboratory were reviewed from the years of 1982 to 2013. Peak latencies, amplitudes, and interpeak intervals were measured when visible. Clinical data were extracted from the medical records. Foals were grouped under disease categori...
Hood DM.Many of the difficulties in managing the horse with chronic laminitis are associated with the foot's mechanical failure. The occurrence of digital collapse cannot be viewed in isolation as the primary therapeutic focus. The circulatory, metabolic, and growth pattern changes induced by the foot's mechanical collapse often serve as major limiting factors to successful rehabilitation. From the discussion above, it is obvious that a significant amount of research is needed to better understand the biomechanical pathologies of the failed foot.
Fuentes-Romero B, Muñoz-Prieto A, Cerón JJ, Martín-Cuervo M, Iglesias-García M, Aguilera-Tejero E, Díez-Castro E.Obesity and its associated complications, such as metabolic syndrome, are an increasing problem in both humans and horses in the developed world. The expression patterns of resistin differ considerably between species. In rodents, resistin is expressed by adipocytes and is related to obesity and ID. In humans, resistin is predominantly produced by inflammatory cells, and resistin concentrations do not reflect the degree of obesity, although they may predict cardiovascular outcomes. The aim of this study was to investigate the usefulness of resistin and its relationship with ID and selected ind...
Baker D, Kreeger J.An expansile, yellow, soft mass was observed in the free wall of the right ventricle of a 3-year-old, male, Morgan, horse at necropsy. The mass was composed of well differentiated adipocytes in solid sheets or infiltrating between muscle fibers with associated myofiber degeneration. The mass was interpreted to be an infiltrative lipoma of the heart.
Beech J, Irby N.Congenital cataracts affecting the fetal and embryonal lens nucleus were found in 12 Morgan horses. Ten of the 12 affected animals were sired by the same stallion and the condition also affected his female half sibling. Although females were almost three times more likely to be affected than males (9 vs 3), the difference was not significant. The ratio of 11 normal to 10 affected offspring by the affected stallion is compatible with an autosomal dominant mode of inheritance.
Bicout DJ, Carvalho R, Chalvet-Monfray K, Sabatier P.The paper examines the prevalence of equine infectious anemia (EIA) in horse populations in the northern part (comprising 89 cities) of Minas Gerais State, Brazil, from January 2002 to December 2004. Data on 8,981 agar gel immunodiffusion test results from the region were used as input for a statistical and autoregressive analysis model to construct a city-level map of the distribution of EIA prevalence. The following EIA prevalence (P) levels were found: 49 cities with 0 < P < or = 0.5%, 26 with 0.5% < P < or = 1.5%, 10 with 1.5% < P < or = 5%, and 4 with 5% < P < or = 25%.
Wierup M, DiPietro JA.The fecal flora of 56 clinically healthy and 23 sick horses were examined bacteriologically for counts of Clostridium perfringens, molds, coliforms, alpha- and beta-hemolytic streptococci, and microbes belonging to genus Bacillus, as well as for the presence of Salmonella spp. Of the healthy horses, 85.7% had a C perfringens count less than 10(1) colony-forming units/g of feces. Of the healthy horses, lowest counts were found in race-horses. Of the sick horses, equine intestinal clostridiosis was diagnosed in 2 horses with large C perfringens counts (10(4) to 10(7) colony-forming units/g) and ...
Hood DM, Amoss MS, Grosenbaugh DA.Raynaud's phenomenon (RP) and equine laminitis in the horse are medical enigmas. Clinical and scientific data were compared to evaluate the degree of similarity that exists between these two peripheral vascular diseases. Data indicate that certain pathologic and pharmacologic aspects seem to have common features. Some of the correlations maybe due simply to both diseases having ischemia of the distal digits as a pathologic component. The exact etiology of the ischemia is not known for either disease. The results of this study suggest the hypothesis that RP and laminitis are the same disease in...
Freestone JF, Wolfsheimer KJ, Ford RB, Church G, Bessin R.Ponies were evaluated for their response to feed withholding and exogenous administration of corticosteroids (dexamethasone 0.04 mg/kg intramuscular [IM]) in an attempt to reproduce the hyperlipemia syndrome. Because insulin resistance has been associated with hyperlipemia, all ponies were initially evaluated for insulin response to an oral glucose load and normal dexamethasone suppression of serum cortisol. Four ponies were identified as hyperinsulinemic reflecting insulin resistance. All ponies had suppressed cortisol concentrations following dexamethasone administration. Feed withdrawal res...
Lindåse S, Nostell K, Söder J, Bröjer J.A hyperbolic relationship between β-cell response and insulin sensitivity (IS) has been described in several species including rodents, dogs, and humans. This relationship has not been elucidated in the horse. Objective: To determine whether the hyperbolic relationship between β-cell response and IS exists in horses by using indices of β-cell response from the oral sugar test (OST) and IS measurements from the euglycemic hyperinsulinemic clamp (EHC). A second aim was to compare how well IS estimates from the OST and EHC correlate. Methods: Forty-nine horses with different degrees of insulin...
Winder NC, Grünig G, Hermann M, von Fellenberg R.Equine bronchoalveolar lavage (BAL) fluid collected from 70 horses and respiratory secretions (RS) obtained from 61 of these horses were evaluated cytologically and grouped according to the histological diagnosis of the lungs from which they were obtained. The histological categories included: normal lung (8 horses); pulmonary eosinophilic infiltration (9 horses); interstitial pneumonia (5 horses); pulmonary hemorrhage (5 horses); and mild (12 horses), moderate (7 horses) and severe (24 horses) chronic small airway disease. In horses with pulmonary disease, all BAL samples and all but one RS s...
Pearson H, Pinsent PJ, Polley LR, Waterman A.Four cases of fatal diaphragmatic rupture in the horse are described. In 2 cases there was no history of injury but the other 2 animals had sustained recent thoracic trauma. Three of the horses had signs of colic and bowel obstruction complicated, in 2 cases, by respiratory embarrassment; the fourth died rapidly, presumably of shock. Previously published cases are reviewed and the causes, clinical effects, diagnosis and treatment of the disorder are discussed.
Johnson PJ, Goetz TE.A 10-month-old Standard-bred colt was examined because of weight loss, fever, and extensive subcutaneous edema of the ventral aspects of its trunk. Diagnosis of granulomatous enteritis was based on D-xylose malabsorption, hypoproteinemia, and rectal mucosal biopsy. Campylobacter fetus subsp fetus was cultured from jugular venous blood when the horse was admitted to the hospital and 24 hours later. Appropriate antimicrobial agents and glucocorticoids failed to effect clinical remission. After euthanasia, granulomatous enteritis was confirmed at necropsy but C fetus subsp fetus was not isolated ...