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Topic:Equine Diseases
Equine diseases encompass a wide range of health conditions that can affect horses, including infectious diseases, metabolic disorders, and genetic conditions. These diseases can impact the overall health, performance, and well-being of horses. Common equine diseases include equine influenza, equine herpesvirus, laminitis, and equine metabolic syndrome. Diagnosis and management of these diseases often require a combination of clinical evaluation, laboratory testing, and appropriate treatment strategies. This page gathers peer-reviewed research studies and scholarly articles that explore the etiology, pathophysiology, diagnosis, and treatment options for various equine diseases, providing valuable insights for veterinarians and researchers in the field.
Dysgerminoma in an Arabian filly. A yearling Arabian filly was referred to the Veterinary Medical Teaching Hospital with a history of weight loss, profound anemia, and peritoneal effusion. At necropsy, a large, soft, mottled tan and red neoplastic mass was at the pelvic inlet replacing the left ovary. Additional tumor nodules of various sizes were disseminated throughout the mesentery, diaphragm, and serosal surfaces of the abdominal viscera. Histologically, the neoplasm had sheets of large round to polygonal cells separated into lobules by fibrous connective tissue with multifocal areas of necrosis. Tumor cells stained strong...
Equine malignant lymphomas: morphologic and immunohistochemical classification. Gross lesions, microscopic appearance, and immunophenotyping are reported in a retrospective study of 31 cases of equine malignant lymphoma. Immunohistochemical studies were performed on archived formalin-fixed, paraffin-embedded tissues. Monoclonal antibodies to surface glycoprotein BLA.36 and intracytoplasmic domains of mb-1 and B29 were used to document the presence of B lymphocytes in the equine tumors. Polyclonal antibody to CD3 and monoclonal antibodies to T-lymphocyte markers CD3 and CD5 revealed the presence of variable numbers of T cells within the equine lymphomas. The neoplastic com...
Effect of the 5-lipoxygenase inhibitor, fenleuton, on antigen-induced neutrophil accumulation and lung function changes in horses with chronic obstructive pulmonary disease. The leukotrienes (LT) LTD4 and LTB4 have been shown to cause bronchoconstriction and neutrophil accumulation, respectively, in horse lungs. Such changes are characteristic of the equine allergic respiratory disease, chronic obstructive pulmonary disease (COPD). To further investigate the role of these putative mediators in the pathogenesis of equine COPD the effect of a 5-lipoxygenase inhibitor, fenleuton, on antigen-induced changes in horses with this condition has been examined. Six horses with COPD underwent a series of four antigen challenges, one month apart, with placebo pre-treatment on...
Molecular basis for antigenic variation of a protective strain-specific antigen of Ehrlichia risticii. Ehrlichia risticii, the causative agent of Potomac horse fever, has recently been isolated from many vaccinated horses with typical clinical signs of the disease. The heterogeneity of the E. risticii isolates obtained from the vaccinated horses necessitates the identification of the molecular basis of strain variations to elucidate the vaccine failure and to aid in the development of an efficient vaccine against this disease. As an attempt, two major cross-reacting surface antigen genes of 50- and 85-kDa antigens, present separately in strains 25-D (isolated in 1984) and 90-12 (isolated in 199...
Diversity among isolates of Actinobacillus equuli and related organisms as revealed by ribotyping. The objective of this work was to examine the diversity within Australian isolates of Actinobacillus equuli and related organisms by the genotypic method of ribotyping. Methods: Ribotyping, performed using the enzyme HaeIII, was used to examine the diversity in 12 field isolates of A equuli (five being capable of fermenting L-arabinose), one field isolate of Pasteurella caballi and two unclassifiable field isolates. Isolates were obtained from Australian horses, except for three isolates of A equuli (one L-arabinose positive and two L-arabinose negative) which were obtained from horses and a p...
Inhibition of glutathione S-transferase activity by the quinoid metabolites of equine estrogens. The risk factors for women developing breast and endometrium cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy (ERT) in particular has been correlated with a slight increased cancer risk, although the numerous benefits of ERT may negate this harmful side effect. Equilenin and equilin are equine estrogens which make up between 30% and 45% of the most widely prescribed estrogen replacement formulation, Premarin (Wyeth-Ayerst). In this study we have synthesized the catechol metabolites of equilenin [4-hydroxyequilenin (4-OHEN)] and equilin [4-hydroxyequ...
General method for the detection and in vitro expansion of equine cytolytic T lymphocytes. Equine immunological research is hindered by the lack of a simple yet reliable general protocol by which to assay CTL activity specific for viral or parasitic antigens. We present here the first comprehensive analysis of the parameters necessary to reliably culture equine T cells and to analyze the antigen specific cytolytic activity of T lymphocytes utilizing the equine infectious anemia virus (EIAV) infection of outbred ponies as a source for in vivo primed T lymphocytes. Effective long-term in vitro culture of equine T cells was determined to require minimally 200 U/ml of recombinant human ...
Stress/strain behaviour of the equine laminar junction. The equine laminar junction plays a vital role in transferring the forces of weight-bearing between the epidermal hoof wall and the bone of the third phalanx, but the way in which it performs this function is poorly understood. Using samples from sites varying proximodistally and circumferentially around the hoof, the stress/strain behaviour of this tissue was characterised in three directions: radial tension and proximodistal and mediolateral shear. The influences of toe angle and length were also examined. For all three test directions, the modulus of elasticity increased with increasing str...
Changes in third carpal bone articular cartilage after synovectomy in normal and inflamed joints. To determine if arthroscopic synovectomy in normal and inflamed joints had temporal or site-related effects on articular cartilage. Methods: Alterations in equine third carpal bone articular cartilage were studied at two time periods: groups 1 and 2 (6 weeks) and groups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) and inflamed carpi (groups 1 and 3). Methods: 16 carpi from eight horses. Methods: Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radioloabeling, proteoglycan (PG) extraction, chromatography, electrophoresis, and...
Redescription of Babesia equi Laveran, 1901 as Theileria equi Mehlhorn, Schein 1998. The horse-parasitizing species Babesia equi Laveran, 1901 was redescribed as Theileria equi Mehlhorn, Schein 1998 and, thus, transferred from one valid genus to another. This transfer was needed since it turned out that this horse parasite showed the relevant characteristics of theilerians with regard to biological data, morphological features, biochemical properties, and molecular biological relationships.
Influence of exogenous hyaluronan on synthesis of hyaluronan and collagenase by equine synoviocytes. To evaluate the influence of exogenous hyaluronan (HA) on in vitro synthesis of HA and collagenase by equine synoviocytes from normal and inflamed joints. Methods: 9 adult horses. Methods: Synoviocytes for culture were taken from the middle carpal joint of 3 horses with normal joints (control) and 6 horses with osteochondral fractures (principal). Synoviocytes were propagated in monolayer cultures and were incubated with 3 commercial HA products at concentrations of 0, 200, 400, and 1,500 micrograms/ml. Newly synthesized HA was radiolabeled with [3H]glucosamine and quantified by cetylpyridiniu...
Effect of a competitive inhibitor of platelet aggregation on experimentally induced laminitis in ponies. To determining whether inhibition of platelet aggregation prevents development of carbohydrate overload-induced alimentary laminitis. Methods: 22 healthy adult ponies. Methods: Acute laminitis was induced by oral administration of corn starch/wood flour to 16 ponies, 8 of which were treated with a synthetic analogue of the platelet fibrinogen receptor antagonist peptide (RPR) RGDS (arginine-glycine-aspartic acid-serine) 110885; 6 ponies served as negative controls. Blood was collected before and at 4, 8, 12, 24, 28, and 32 hours after administration of carbohydrate overload, and PCV, total pla...
[The proximal sesamoid bone of the horse; vascular and neurologic characteristics]. Sesamoiditis is characterized clinically by repeated lameness and radiologically by changes in the proximal sesamoid bones. This thesis, which was defended in June 1997, investigated two characteristics of sesamoiditis, namely the arterial blood supply and the innervation of the proximal sesamoid bones, in order to gain more insight into the etiopathogenesis of sesamoiditis. Experiments with patient material showed that the proximal sesamoid bones have an enormous arterial reserve, due in part to the formation of an arterial shift. Moreover, the sesamoid bones have their own sensory innervatio...
Clinical appearances, healing patterns, risk factors, and outcomes of horses with fungal keratitis: 53 cases (1978-1996). To compare initial clinical appearances, healing mechanisms, risk factors, and outcomes of horses with fungal keratitis. Methods: Retrospective analysis. Methods: 52 horses (53 eyes) with fungal keratitis. Methods: Medical records and clinical photographs of eyes were reviewed. Keratomycoses were categorized on the basis of clinical appearance at initial examination and pattern of healing. Results: Five distinct forms of mycotic keratitis were recognized. Of 53 affected eyes, 34 (64%) retained sight and had varying degrees of corneal scarring after treatment, 6 (11%) had a cosmetic appearance ...
Observations on the Echinococcus granulosus horse strain in Spain. The Spanish sheep and horse strains of Echinococcus granulosus possess several differential characteristics in their metacestode stage. Cysts from sheep vary widely in size and fertility, but they usually have a thin cyst wall and, when fertile, a whitish hydatid sand formed by brood capsules and protoscoleces. Two types of infections have been observed in horses: one resembling that of sheep, caused by small, non-fertile cysts with a thin wall, and a second type caused by medium to large, always fertile cysts with a thick wall. In this latter case, hydatid sand is always dark brown in color a...
Occurrence and importance of glomus organs (Hoyer-Grosser’s organs) in the skin of the equine and bovine mammary gland. Glomus organs (Hoyer-Grosser's organs) were frequently found in the corium and the subcutis of the skin of the equine and bovine mammary gland. They were most frequently situated in the border zone between the stratum profundum and the stratum superficiale corii. These specialized vascular structures (arterio-venous anastomosis) were present in all investigated skin areas. Although the glomus organs varied in size and shape, they possessed common histologic structures: an arteriole entered the connective capsule of the glomus and divided into strongly convoluted arterio-venous channels; the ar...
Identification of a granulocytic Ehrlichia strain isolated from a horse in Switzerland and comparison with other rickettsiae of the Ehrlichia phagocytophila genogroup. This case report describes a 12-year-old Arabian mare with granulocytic ehrlichiosis. Clinical signs included fever, apathy, anorexia, icterus, limb edema, and reluctance to move. Examination of buffy coat smears revealed Ehrlichia organisms in neutrophils and eosinophils. A band of 1,428 bp was amplified from DNA of leukocytes via nested PCR and was identified as part of the Ehrlichia 16S rRNA gene. It differed from the gene sequences of Ehrlichia phagocytophila and E. equi at two and three positions, respectively. Interestingly, the nucleotide sequence of the 16S rRNA was 100% identical to t...
Experimental transmission of Ehrlichia equi to horses through naturally infected ticks (Ixodes pacificus) from Northern California. We report the experimental transmission of Ehrlichia equi from naturally infected Ixodes pacificus ticks to horses. Three weeks after exposure to ticks, two of three horses developed clinical signs compatible with E. equi infection, while one horse remained asymptomatic. 16S rRNA gene PCR of blood leukocyte lysates was positive for all horses at various time points; two horses seroconverted. The 16S rRNA gene sequences amplified from tick-exposed horses showed more than 99% homology to corresponding fragments of the 16S rRNA genes of E. equi, Ehrlichia phagocytophila, and the human granulocyti...
Datura seed intoxication in two horses. A sunflower-based feed supplement grossly contaminated with the seed of a Datura sp. resulted in severe signs of poisoning in 2 horses. One horse died peracutely of acute gastric dilatation and rupture following ingestion of the contaminated feed. The 2nd horse developed unresponsive paralytic ileus that led to euthanasia. Examination of the feed and gastrointestinal contents of both horses showed a high proportion of the characteristic Datura sp. seeds. The clinical signs and pathology in both cases were consistent with intoxication by the parasympatholytic alkaloid components of Datura sp.
[Halicephalobus (Syn. Micronema) deletrix as a cause of granulomatous gingivitis and osteomyelitis in a horse]. Therapy resistant swellings of the maxillary region and unilateral nasal discharge in older horses are mainly thought to be consequences of neoplasias of the oral cavity, especially of the gingiva and the teeth, or to develop from tumours of the nasal cavity. We report an unilateral swelling of the left nasal and buccal region in a 13-year-old gelding, which was accompanied by an aggressive destruction of involved osseous tissue due to a severe proliferative granulomatous inflammation. The granuloma was caused by the nematode Halicephalobus (syn. Micronema) deletrix. This nematode infection is...
Efficacy of moxidectin 2% oral gel against second- and third-instar Gasterophilus intestinalis De Geer. In a trial designed to evaluate the efficacy of the recommended dosage of moxidectin 2% oral gel against the gastric stages of Gasterophilus spp., 14 ponies were selected from a herd on the basis of the inclusion criterion of the presence of Gasterophilus spp. eggs attached to their hair coats. After random allocation, the ponies were treated with 1 of 2 treatments, moxidectin 2% equine gel in a single dose at the commercial dosage of 400 microg moxidectin/kg body weight or placebo gel. The animals were necropsied 14 days posttreatment. Efficacies against second- and third-instar Gasterophilus...
Direct sequencing of the HA gene of clinical equine H3N8 influenza virus and comparison with laboratory derived viruses. Equine influenza viruses propagated in the laboratory in alternate hosts such as embryonated hens' eggs or mammalian cell culture have been analysed by HA sequencing and antigenically and their sequence compared to the original virus present in clinical material. In contrast to clinically derived human influenza virus which generally grows in MDCK cells without change, the data for equine influenza virus were less clear in that variants of equine virus were derived in both eggs and cells. The study indicated that the current use of eggs for equine influenza virus surveillance and vaccine produ...
[Tinea caused by Trichophyton equinum]. We report on the first human infection with Trichophyton equinum in Germany, which was transmitted from an infected pony to a 12-year old girl. Trichophyton equinum was identified by its morphology, dependency on nicotinic acid, hair perforation, and enzyme production. A noteworthy new observation was the development of white pleomorphic tufts on the surface of thalli grown on potatoe-dextrose agar. The girl's tinea was non-inflammatory and responded promptly to topical treatment, whereas the pony's strongly inflammatory lesions persisted for months. In supernatants of cultures supplemented wi...
