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Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Blood gas measurements during exercise: errors due to temperature correction. This study assessed the degree to which correcting blood gas measurements to rectal temperature (Tre) rather than to the temperatures at which gas exchange occurs [pulmonary arterial (Tpa) or intramuscular (Tm)] introduces errors into blood gas analysis of exercising mammals. Horses and steers weighing 450 kg were run on a treadmill at speeds up to those eliciting maximal rates of O2 consumption (VO2max), and temperatures were measured in various body compartments. In both species Tpa rose faster than Tre during the run, the degree of dissociation being a function of exercise intensity and dur...
Effects of a draft-loaded interval-training program on skeletal muscle in the horse. Five Standardbred trotters were trained on a treadmill 3 times/wk for 12 wk by intervals of draft-loaded exercise. The draft load was 34 kp and the velocity approximately 7 m/s. Muscle biopsies were taken from the gluteus medius and longissimus muscles before training and after 2, 4, 8, and 12 wk of training and from the brachiocephalicus muscle before and after training. Both the percentage and the area of type IIa fibers increased and the percentage of type IIb fibers decreased in the gluteus medius muscle during the first 2 wk of training, and then no further significant difference was note...
Intestinal healing and methods of anastomosis. Optimal intestinal healing occurs when like layers of the intestinal wall are aligned. Hand-sewn, double-layer, end-to-end anastomosis that apposes the mucosa and produces slight inversion of the seromuscular layer is recommended to minimize adhesion formation and provide reasonable alignment of the intestinal layers. Stapled, everted, triangulated, end-to-end anastomosis is not recommended because of extensive adhesion formation and poor healing of the intestinal layers. The preferred stapled techniques create an inverting, side-to-side stoma between the bowel segments.
Characterization of plasma progesterone concentrations for two distinct luteal morphologies in mares. Plasma progesterone concentrations in mares were determined in two experiments during the time that the luteal glands were detectable by transrectal ultrasonography. In both experiments, corpora lutea were classified into two types of morphologies based on their ultrasonic appearance: centrally nonechogenic luteal glands (fluid-filled) and uniformly echogenic luteal glands (non-fluid-filled). In Experiment 1, daily blood samples were taken from horse mares during August through October and May through July. There were no significant effects of season or luteal morphology on progesterone concen...
Release of immunoreactive arachidonate metabolites by equine endometrium in vitro. The ability of equine endometrium to release prostaglandin (PG) F, PGE2, and leukotriene (LT) B4 was studied in vitro, using endometrial tissue from diestrous mares. Because of the high cross-reactivity of the PGF antiserum with PGF1 alpha and with PGF2 alpha, results were quoted as total immunoreactive PGF. Significant concentrations of these arachidonate metabolites were released into tissue culture medium between 1 and 24 hours of incubation. Significantly higher concentrations of PGE, but not of PGE2 or LTB4, were released from endometria of mares with chronic endometritis than from genita...
Prevention of large colon displacements and volvulus. Results of these studies have demonstrated that colopexy of the left large colon to the abdominal wall is a relatively simple and quick procedure that is permanent 1 year after surgery. The technique does not appear to be associated with long-term weight loss or abdominal pain after surgery. It has been used in pregnant mares, both experimentally and clinically, without apparent complications. In addition, horses used for pleasure-riding and show hunting have returned to performance and have not had complications. Large colon resection is a useful technique, especially for animals with strangu...
Large colon resection. With large colon resection and anastomosis, up to 95 per cent of the length of the large colon has been successfully removed. A hand-sewn end-to-end anastomosis is effective for lesions in the left dorsal colon and pelvic flexure. Transection and a side-to-side anastomosis with stapling equipment is most effective for extensive resections (greater than 50 per cent). Horses with extensive colon resection (95 per cent) have permanent deficiencies of water absorption and digestion of cellulose and protein. Fermentative capacity is reduced, owing to decreased particulate matter retention time in t...
Inertance of the respiratory system in ponies. The purpose of the present work was to measure the pulmonary inertance (IL) in ponies and to analyze its potential influence on the mechanics of breathing and on their aptitude to increase ventilation during exercise. Five healthy ponies 2.4-4 yr old [mean wt 255 +/- 15 (SE) kg] were used. On the one hand, inertance of the respiratory system (Irs) was computed from the value of the resonant frequency (fr) measured by the forced oscillation technique. On the other hand, respiratory airflow, tidal volume (VT), and transpulmonary pressure (PL) changes were recorded while the ponies were performin...
[Seasonal changes in blood testosterone in the Giara horse]. The blood testosterone changes in three Giara stallions, average age 8 years old and average weight 183 Kgs, were checked weekly for a year using a radioimmunological method. The horses showed a highly seasonal hormonal activity concentrated in the first half of the year (winter and spring). In the second half of the year (summer and fall) the stallions showed low levels of testosterone. The highest level of the androgen hormone occurred in April, the lowest in October. The absolute levels of this hormone agreed substantially with the relative literature.
Immunologic and hematologic responses in ponies with experimentally induced Strongylus vulgaris infection. Immunologic and hematologic responses were examined in 4 ponies with experimentally induced Strongylus vulgaris infection and in 5 helminth-free ponies. Two ponies were inoculated with 200 larvae and 2 were inoculated with 700 larvae of S vulgaris and then were reinoculated with the same numbers of larvae 34 weeks later. Initial response of the ponies inoculated with S vulgaris was S vulgaris antigen-induced lymphocyte response that developed 1.5 to 3 weeks after inoculation and did not persist. Development of antigen-reactive lymphocytes was followed sequentially by a biphasic complement-fixi...
The pathophysiology of intestinal damage: effects of luminal distention and ischemia. Intestinal edema, luminal distention, and ischemia are common pathologic processes involved in producing the intestinal damage found during surgical exploration for acute abdominal disorders in the horse. The severity of intestinal edema depends on the degree of altered intravascular forces and changes in capillary permeability. Capillary hydrostatic pressure rises as the less pliable venules and veins become occluded during intestinal obstruction. Concurrently, the production of various endogenous products that damage the vascular wall leads to increases in capillary permeability and protein ...
Thoracic neoplasia in equids: 35 cases (1967-1987). Thirty-two horses and 3 ponies had neoplasia involving the thoracic cavity. Lymphosarcoma of the thorax was found in 19 (54.2%) of the equids. The other 16 equids had metastatic adenocarcinoma (7 horses; 20%), metastatic squamous cell carcinoma (5 equids; 14.3%), metastatic hemangiosarcoma (3 equids; 8.6%) or undifferentiated sarcoma (1 horse; 2.9%). Thoracic neoplasia was diagnosed before death in 15 equids (42.9%).
Dimethyl sulfoxide intrauterine therapy in the mare: effects upon endometrial histological features and biopsy classification. The effects upon equine endometrial histological features produced by 10 to 30% concentrations of dimethyl sulfoxide (DMSO) in sterile saline were compared with the effects of sterile saline (0.9% NaCl) alone as an intrauterine infusion therapy in 16 barren mares. No harmful histological changes were noted (P>0.05) as a result of the therapy. Thirty percent intrauterine DMSO therapy produced a significant (P0.05); however, there was a trend toward a higher pregnancy rate following DMSO therapy. The inability to control for sire variability in the breeding trials may have contributed toward ...
DNA restriction analysis of equine adenovirus serotype I. The three equine adenovirus strains isolated in different locations showed a similar cleavage pattern with HindIII and the DNA homology among the strains was confirmed by Southern blot hybridization. The three strains revealed differences in cleavage patterns with BamHI, EcoRI and PstI, suggesting the presence of DNA polymorphisms among equine adenoviruses.
Equine interferons following exposure to equid herpesvirus-1 or -4. When 23 ponies were infected with equid herpesvirus-1 or -4 (EHV-1 or EHV-4), nasal shedding of interferon (IFN) correlated closely with the duration of viral excretion. Equine interferon (EqIFN) was detected in the serum only from animals infected with the EHV-1 virus, and here high levels correlated with clinical symptoms of locomotor disorder and indicated a poor prognosis. Low levels of IFN were detected in explanted mononuclear cells from ponies infected with either virus.
Normal intestinal motility. Perhaps because of the inherent difficulty in using horses as experimental animals, only a relatively small amount of data is as yet available regarding normal equine gut motility. However, it is clear that the horse is fundamentally similar to other mammalian species studied. The neural and humoral control of gut activity requires much exploration; it is likely that, in the horse, some of this information will be derived during the investigation of the effects of various substances that might have clinical relevance. This is alluded to in the chapter that follows (The Effects of Pharmacologic...
Kinematic analysis of cutting horses working a mechanical flag. High-speed cinematography was used to record the movements of 12 cutting horses performing a standard test with a mechanical flag. Based on their previous competitive performances, horses were classified into 2 groups: group 1, composed of 5 moderately successful or average performers that had won less than $35,000 in purse money; and group 2, composed of 7 highly successful or elite performances that had amassed greater than $35,000 in competition earnings. Analysis of the results indicated that, compared with horses of the average group, the elite horses had faster reaction times in response...
[Bilateral pleuritis following esophageal fistula in a horse as a complication of a Gasterophilus infection]. A six-year-old pregnant Haflinger mare of 510 kilograms died from bilateral pleurisy following a hospitalisation period of ten days, during which she was treated with various antibiotics. At necropsy a bilateral fibrinopurulent pleurisy accompanied by an ulceration of the cardia of the stomach measuring once cm2 was found. In the wall of the oesophagus, close to the cardia, there was a fistula harbouring a 3rd stage Gasterophilus larva. The epithelial layer at this site was unimpaired and no gross connection between the fistula and the ulceration of the cardia was observed. The fistula was in ...
A field evaluation of anthelmintics in horses in Sweden. A field evaluation of anthelmintics in 336 horses on 37 farms was conducted between February and May 1986 in Sweden. The herds, each comprising at least eight horses, had histories of grazing on permanent pastures and receiving regular treatments against parasites at least three times a year. Small strongyles were refractory to (pro)-benzimidazole drugs in all but one of 23 herds examined. There was an average reduction in egg output of approximately 60%, and approximately 30% of 205 horses examined were shedding less than 100 eggs g-1 7 days after treatment. There was great between-herd varia...
Clinical use of the neuromuscular blocking agents atracurium and pancuronium for equine anesthesia. Neuromuscular blocking agents (muscle relaxants) are useful and common adjuncts to general anesthesia for human beings, but have not been used extensively during anesthesia of large animal species. Over a 3-year period, atracurium or pancuronium were used as adjuncts to general anesthesia for 89 anesthetic procedures in 88 equids (of 18 breeds and age ranging in age from 5 weeks to 25 years) at the teaching hospital. Forty-one of the anesthetic procedures were for abdominal surgery, and orthopedic (n = 19), ophthalmologic (n = 17), thoracotomy (n = 1), and soft tissue (n = 14) procedures compo...
Three cases of non-displaced radial fracture in horses. Three horses with non-displaced fractures of the radius were examined. The affected animals showed a sudden onset of severe forelimb lameness with swelling of the antebrachium. Two cases had associated wounds on the medial aspect of the distal radius. The diagnoses were confirmed on radiographic examination. All three cases were treated conservatively by box rest. In one case slight further displacement of the fracture occurred three weeks after the initial injury but all the fractures went on to heal. The three horses returned to work but two were limited to light ridden exercise.
Distribution and density of neuropeptide Y-immunoreactive nerve fibres and cells in the horse urinary bladder. The distribution and density of neuropeptide Y (NPY)-immunoreactive nerve fibres and cells were determined in the urinary bladder of the horse by using the peroxidase-antiperoxidase (PAP) immunohistochemical method. Numerous undulating NPY-immunoreactive nerve fibres were found throughout the vesical wall, sometimes forming nerve bundles which ramified repeatedly as they coursed through the connective tissue septa to give rise to smaller bundles or single fibres which projected into the muscle fascicles forming muscular nerve plexuses, mainly in the bladder base. In the submucosa of this regio...
Transfer of deep circumflex iliac flaps to the tarsus by microvascular anastomosis in the horse. Eighteen deep circumflex iliac flaps were elevated in healthy adult horses. Four flaps survived well when elevated as islands, but five orthotopic flaps and nine heterotopic flaps transferred to the tarsus and face failed. Technical reasons could explain the failure of the orthotopic flaps, but not the heterotopic flaps. Failure of the heterotopic flaps was apparently caused by the no-reflow phenomenon.
Light and electron microscopy of keratinization in the laminar epidermis of the equine hoof with reference to laminitis. The laminar epidermis (epidermis parietis) of hooves from 14 clinically normal horses, 6 months to 15 years old, was examined by light and electron microscopy and immunofluorescence to measure the contributions of this region to the formation of the hoof wall. By their progressive keratinization to form primary epidermal laminae, the secondary epidermal laminae ultimately contributed about 20% of the thickness of the hoof wall (as revealed in the white line [zona alba]). The keratinized, primary epidermal laminae were developed to a height of 4 mm during their proximodistal-course, much of thi...
Colostral and serum IgG, IgA, and IgM concentrations in Standardbred mares and their foals at parturition. Immunoglobulin G, IgM, and IgA concentrations were measured in serum collected from 36 Standardbred mares within 12 hours of foaling, in colostrum collected within 6 hours of foaling, and in serum collected from foals 24 to 48 hours after birth. In serum collected from mares after parturition, mean concentrations of IgG, IgM, and IgA were 2,463.9 +/- 1,337.3 mg/dl, 136.4 +/- 218 mg/dl, and 305.2 +/- 237.5 mg/dl, respectively. In serum from foals, mean concentrations of IgG, IgM, and IgA were 1,953.3 +/- 1,635 mg/dl, 33.8 +/- 30.4 mg/dl, and 58.4 +/- 42.2 mg/dl, respectively. In colostrum, mean...
