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Topic:Disease Etiology
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.
A case-control study of respiratory disease in Thoroughbred racehorses in Sydney, Australia. In order to investigate the role of infectious agents in the aetiology of lower respiratory tract disease in Thoroughbred racehorses, a matched case-control study was conducted. Cases were identified by the presence of coughing, and were compared to a control population matched on time of sample collection and location within the same training establishment. Tracheal wash samples were collected from 100 cases and 148 controls. Case horses were more likely than controls to have endoscopic and cytological evidence of airway inflammation. There was no significant association between serological e...
Bovine papillomavirus DNA in neoplastic and nonneoplastic tissues obtained from horses with and without sarcoids in the western United States. To determine the incidence of bovine papillomavirus (BPV) type 1 or 2 in sarcoids and other samples of cutaneous tissues collected from horses in the western United States. Methods: 55 horses with sarcoids and 12 horses without sarcoids. Methods: Tissue samples (tumor and normal skin from horses with sarcoids and normal skin, papillomas, and nonsarcoid cutaneous neoplasms from horses without sarcoids) were collected. Tissue samples were analyzed for BPV-1 or -2 DNA, using a polymerase chain reaction (PCR) and restriction fragment length polymorphism. The PCR products from 7 sarcoid-affected ho...
Expression of interleukin-1beta in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. To study expression of interleukin-1beta (IL-1beta) in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. Methods: 8 healthy adult horses with no signs of laminitis. Methods: Black walnut extract was administered via nasogastric tube to 4 horses, and water was administered to the remaining 4 (controls). Complete blood counts and physical examinations were performed every 30 minutes after administration of black walnut extract or water. General anesthesia was induced when total WBC count decreased by 30% in horses given the black walnut extract and 3 hours...
Use of canaliculorhinostomy for repair of nasolacrimal duct obstruction in a horse. Obstruction of the nasolacrimal outflow pathway in horses is not uncommon. Causes of obstruction include foreign bodies, trauma, and congenital abnormalities. Placement of a nasolacrimal retention stylette may prove challenging.
Verminous arteritis in a 3-month-old thoroughbred foal. Strongylus vulgaris migration and cranial mesenteric arterial thrombus formation resulted in fatal colic in a 3-month-old Thoroughbred foal. Vascular damage associated with S. vulgaris occurs early in the course of infection and, despite widespread use of broad-spectrum anthelmintics, appropriate management is still essential to minimize exposure of young animals to this parasite.
SRY-negative XX sex reversal in a pony: a case report. A three year old pony with sexually ambiguous external genitalia was found to have a normal female karyotype (64, XX) and bilateral inguinal testes. The PCR analysis of blood samples revealed the absence of the Y chromosome sequences SRY, eTSPY and ZFY. No Y chromosome sequences were identified in DNA extracted from the gonads. The mechanism whereby XX sex reversal occurs in the absence of SRY is unknown.
Risk factors for and outcomes of noncatastrophic suspensory apparatus injury in Thoroughbred racehorses. To evaluate effects of toe grabs, exercise intensity, and distance traveled as risk factors for subclinical to mild suspensory apparatus injury (SMSAI) in Thoroughbred racehorses and to compare incidence of severe musculoskeletal injury (MSI) in horses with and without SMSAI. Methods: Nested case-control study. Methods: 219 Thoroughbred racehorses racing or in race training. Methods: Racehorses were examined weekly for 90 days to determine incidence of suspensory ligament injury and monitor horseshoe characteristics. Every horse's exercise speeds and distances were recorded daily. Conditional ...
A multicenter, matched case-control study of risk factors for equine laminitis. Risk factors for equine laminitis were examined in a prospective case-control study of the 258 cases seen at six collaborating veterinary teaching hospitals over a 32-month period. Case-control pairs were matched on institution, clinician, and season of diagnosis. The 90% of case-control pairs (78 acute, 155 chronic) that had complete data for age, gender, and breed were used in separate conditional logistic-regression models for acute and chronic laminitis. There was an increase in risk for horses with acute laminitis from 5 to 7 years of age (OR 4.7, 95% CI 1.3-16) and from 13 to 31 years of...
Equine infectious anemia virus genomic evolution in progressor and nonprogressor ponies. A primary mechanism of lentivirus persistence is the ability of these viruses to evolve in response to biological and immunological selective pressures with a remarkable array of genetic and antigenic variations that constitute a perpetual natural experiment in genetic engineering. A widely accepted paradigm of lentivirus evolution is that the rate of genetic variation is correlated directly with the levels of virus replication: the greater the viral replication, the more opportunities that exist for genetic modifications and selection of viral variants. To test this hypothesis directly, we ex...
Cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. and demographic, clinical and tick-exposure factors in Swedish horses. A cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. in Swedish horses was conducted to evaluate associations with demographic, clinical and tick-exposure factors. From September 1997-1998, blood samples from 2018 horses were collected from the animals presented to veterinary clinics affiliated with the Swedish Horserace Totalizator Board (regardless of the primary cause for consultation). Standardized questionnaires with information both from owners and attending veterinarians accompanied each blood sample. The apparent seroprevalenc...
Detection of Babesia caballi and Babesia equi in Dermacentor nuttalli adult ticks. Ticks play an important role in human and veterinary medicine particularly due to their ability to transmit protozoan pathogens. In this study we have demonstrated that polymerase chain reaction (PCR) and nested PCR methods enabled detection of Babesia caballi and Babesia equi in field isolates of Dermacentor nuttalli adult ticks from Mongolia. Primers specific for 218 bp fragment merozoite antigen 1 (EMA-1) gene of B. equi successfully amplified products from all samples of D. nuttalli adult ticks while primers for the 430 bp fragment product from BC48 gene of B. caballi amplified products fr...
The nine-banded armadillo (Dasypus novemcinctus) is an intermediate host for Sarcocystis neurona. The nine-banded armadillo (Dasypus novemcinctus) is an intermediate host of at least three species of Sarcocystis, Sarcocystis dasypi, Sarcocystis diminuta, and an unidentified species; however, life cycles of these species have not been determined. Following feeding of armadillo muscles containing sarcocysts to the Virginia opossum (Didelphis virginiana), the opossums shed sporulated Sarcocystis sporocysts in their faeces. Mean dimensions for sporocysts were 11.0x7.5 microm and each contained four sporozoites and a residual body. Sporocysts were identified as Sarcocystis neurona using PCR and...
Studies on the supply of immunoglobulin G to newborn camel calves (Camelus dromedarius). A major problem in camel productivity is the high mortality rate of camel calves in the first 3 months. The causes for mortality are mainly poor management practice and infectious diseases. The purpose of this research, carried out on a ranch in Kenya, was to determine the immunoglobulin G (IgG) concentration in camel colostrum as well as the extent of the calves' passive immunization by maternal antibodies. IgG concentration in colostrum and in the serum of the calf were measured during the first 3 d of life. Evaluation was carried out by comparing the respective values with those for horses ...
Factors associated with Salmonella shedding among equine colic patients at a veterinary teaching hospital. To evaluate factors potentially associated with fecal Salmonella shedding among equine patients hospitalized for colic at a veterinary teaching hospital and to determine the effects of probiotic treatment on fecal Salmonella shedding and clinical signs. Methods: Longitudinal study and controlled trial. Methods: 246 equine colic patients. Methods: History and medical information were obtained from patient records. Fecal and environmental samples were submitted for aerobic bacterial culture for Salmonella enterica. Fifty-one patients were treated with a commercially available probiotic; 46 were ...
Cytokeratins of the matrices of the chestnut (torus carpeus) and periople in horses with acute laminitis. To determine whether there is a change in the expression of cytokeratins in the epidermal cells of the non-weight-bearing parts of the limb in horses with acute laminitis and thus determine whether the morphologic changes that develop in the periople and chestnut (torus carpeus) of horses early in acute laminitis are caused by inhibition of keratinocyte differentiation. Methods: 8 horses with acute laminitis. Methods: Tissue specimens were obtained from the chestnuts of all 8 horses and from the stratum externum of the hoof wall of 3 horses. Tissue specimens were obtained within 48 hours of th...
Molecular epidemiology of Salmonella Heidelberg in an equine hospital. From 1992 to 1997, multi-drug resistant (MDR) Salmonella Heidelberg isolates were cultured from a number of horses hospitalised in a veterinary hospital in Victoria, Australia. To examine the relationships between the cases, 28 isolates from the hospital were compared by pulsed field gel electrophoresis (PFGE), IS200 element profiles, antimicrobial resistance patterns, plasmid profiles and phage typing. The PFGE patterns following digestion with XbaI and BlnI restriction endonucleases showed that the isolates from the veterinary hospital originated from a common source. These isolates also had...
Association of endometriosis in horses with differentiation of periglandular myofibroblasts and changes of extracellular matrix proteins. Periglandular fibrosis and cystic dilation of uterine glands are associated with equine endometriosis. The presence of extracellular matrix proteins (collagen type I, III and IV, laminin and fibronectin) in healthy and endometriotic specimens was demonstrated by immunohistochemistry. The distribution of collagen I, but not collagen III, was dependent on the stage of the oestrous cycle. The arrangement of collagen I and collagen III in endometriotic specimens was similar to that in normal endometrium. In periglandular fibrosis, collagen IV, laminin and fibronectin deposition outside the basemen...
Upregulation of mRNA of interleukin-1 and -6 in subchondral cystic lesions of four horses. This study investigated the potential association of interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in subchondral cystic lesions (SCL) in horses. With the technique of in situ hybridisation in paraffin sections of fibrous tissue of SCL and quantitative real-time PCR in fresh frozen fibrous tissue and undecalcified bone sections of SCL embedded in acrylic resin, upregulation of mRNA of both cytokines could be demonstrated. mRNA of IL-1beta was upregulated at the periphery of the cystic lesion adjacent to normal bone, whereas IL-6 mRNA was upregulated within the fibrous tissue found with...
The role of subchondral bone in joint disease: a review. Subchondral bone plays a role in the pathogenesis of osteochondral damage and osteoarthritis in horses and humans. Osteochondral fragmentation and fracture, subchondral bone necrosis and osteoarthritis are common diseases in athletic horses, and subchondral bone is now thought to play an integral role in the pathogenesis of these diseases. There have been numerous research efforts focused on articular cartilage damage and its pathogenesis, yet comparatively little effort focused on subchondral bone pathology or the coordinated disease states of the osteochondral tissues. The purpose of this re...
Relationships of age and shape of the navicular bone to the development of navicular disease: a radiological study. Estimating the shape of the proximal articular border of the navicular bone and grading the radiological navicular bone condition (grades 3 and 4 representing the most severe changes), the aim of this study was to assess potential age-related implications of the previously reported shape predisposition to navicular disease in 746 normal and 174 clinically affected Dutch Warmbloods age 3-19 years. A significant, age-independent, shape-grade association found in normal and affected horses emphasises the fundamental character of the shape predisposition to navicular disease. A significant age-rel...
Scapulohumeral osteoarthritis in 20 Shetland ponies, miniature horses and falabella ponies. This paper describes the clinical and diagnostic features of 20 cases of scapulohumeral osteoarthritis in Shetland ponies, miniature horses and falabella ponies. The history and clinical signs were similar in all the cases Radiographically they all had consistent changes which consisted predominantly of articular osteophytes and periarticular enthesiophytes. Six of the cases had radiographic evidence of dysplasia of the scapulohumeral joint, although it was uncertain whether this was a primary or a secondary finding. No specific treatment appeared to be advantageous. At follow up, six of the p...
beta-Subunit 102-104 residues are crucial to confer FSH activity to equine LH/CG but are not sufficient to confer FSH activity to human CG. Horse LH/CG (eLH/CG) and donkey LH/CG (dkLH/CG) are strictly LH-specific in their respective homologous species. However, both bind to the FSH receptors from non-equid species, whereas the zebra hormone (zbLH/CG) does not. The FSH/LH ratio of eLH/CG and of the alphadkbetae hybrid is about tenfold higher than that of dkLH/CG and of the alphaebetadk hybrid, showing that the betae subunit contains the structural features responsible for the high FSH activity of eLH/CG. Only six amino acid positions (51, 94, 95, 102, 103 and 106) are unique to the betae subunit when compared with the betadk and be...
In vitro evidence for a bacterial pathogenesis of equine laminitis. Utilizing an in vitro laminitis explant model, we have investigated how bacterial broth cultures and purified bacterial proteases activate matrix metalloproteinases (MMPs) and alter structural integrity of cultured equine lamellar hoof explants. Four Gram-positive Streptococcus spp. and three Gram-negative bacteria all induced a dose-dependent activation of MMP-2 and MMP-9 and caused lamellar explants to separate. MMP activation was deemed to have occurred if a specific MMP inhibitor, batimastat, blocked MMP activity and prevented lamellar separation. Thermolysin and streptococcal pyrogenic ex...
Putative uremic encephalopathy in horses: five cases (1978-1998). To determine historical, physical examination, clinicopathologic, and postmortem findings in horses with putative uremic encephalopathy. Design-Retrospective study. Animals-5 horses with renal failure and neurologic disease not attributable to abnormalities in any other organ system. Methods: Medical records from 1978 to 1998 were examined for horses with renal disease and neurologic signs not attributable to primary neurologic, hepatic, or other diseases. Signalment, history, physical examination findings, clinicopathologic data, renal ultrasonographic findings, and postmortem data were revie...
