"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.
Muylle E, Vandenhende C, Oyaert W, Thoonen H, Vlaeminck K.Thirty-two horses were examined with a history of poor performance and unthriftiness several months after the ingestion of feed containing monensin sodium. Cardiac abnormality was diagnosed in 8 cases and suspected in 4 others. Necropsy examinations were performed on 6 cases with marked clinical symptoms and evidence of circulatory failure was found. Marked cardiac myopathy and fibrosis was a consistent feature. It is concluded that ingestion of monensin sodium by horses may cause either acute death or delayed cardiac circulatory failure as a result of specific cardiac myodegeneration.
Tranquilli WJ, Manohar M, Thurmon JC, Manning JP.Long-term catheterisation of the coronary sinus using a specially designed catheter was accomplished in 6 ponies via a right lateral thoracotomy. The catheter comprised a 10 to 12 cm long stiff segment (Teflon) joined to a 100 cm length of pliable medical grade (vinyl) tubing. Catheters were kept functional up to 10 weeks postoperatively. Location of the catheter tip was verified by determining the oxygen tension of anaerobically withdrawn blood samples. Normal values of oxygen tension of the coronary sinus blood in ponies were similar to those reported for the dog, whereas oxygen content was ...
Purohit RC, Mysinger PW, Redding RW.A continuous series of electroencephalograms (EEG) was obtained from each of 6 mature horses which had been given xylazine and ketamine hydrochloride IV. Electrocardiograms and respiratory rates were also obtained. The EEG of the unsedated standing adult horse displayed a dominant fast activity in the range of 25-35 Hz, 5-30 microV superimposed over slower 1-4 Hz, 10-50 microV activity with occasional 10-14 Hz, 10-40 microV spindle-type activity. The xylazine-sedated horse displayed hypersynchronous EEG patterns, with the dominant activity being 1-3 Hz, 10-70 microV with overlying mixed freque...
Simpson CF, Buergelt CD.The alveoli of the lungs of 2 aborted foals contained elongated, dense bodies when examined histologically and by transmission and scanning electron microscopy. By light microscopy, the bodies (10 to 40 micrometers in size) stained intensely with the Gram stain, and up to 10 were present within an alveolus. Electron microscopy determined that such bodies were not cellular in origin but appeared to be a congealed fluid product composed of layers of fibrillar-like material. From the human literature, it was concluded that these intraalveolar bodies were probably congealed amniotic fluid.
Gunn HM.A modification of the histochemical reaction to demonstrate myosin adenosine triphosphatase activity in skeletal (striated) muscle was used to define the density of capillaries in transverse sections of 3 muscles (semitendinosus, diaphragm, and pectoralis transversus) of horses and dogs. Thoroughbred horses and Greyhound dogs, breeds noted for their speed in running, were compared with other members of their respective species. Thoroughbred cross horses were grouped with non-Thoroughbreds for comparison with Thoroughbreds. The area of muscle supplied by a capillary was remarkably similar in mu...
Joyner LP, Donnelly J, Huck RA.The results of complement fixation (CF) test for equine piroplasmosis on sera from horses destined for international movement from Great Britain and Ireland are presented and analysed. No horses born and continuously resident in the British Isles were found carrying CF antibodies to either Babesia equi or B caballi. Positive animals were found to have association with the following countries where known tick vectors occur: Spain, Portugal, Belgium, France, Poland, USSR and Arabian Gulf countries. Data on the persistence of CF antibodies in animals subjected to repeated testing showed that some...
Orpin CG.Microscopic examination of horse caecum contents revealed vegetative growth of phycomycete fungi on particles of digesta, and uniflagellated cells similar to fungal zoospores in the liquid phase. Three morphologically distinct isolates of strictly anaerobic phycomycete fungi were obtained from the caecum contents and cultured in vitro. Two of the isolates were able to utilize a wide range of plant carbohydrates for growth, including alpha-cellulose, xylan and particulate starch, and extensively digested water-insoluble plant tissues.
Stover SM, Brown MP, Kelly RH, Farver TB, Knight HD.Six adult mares were given a single dose of aqueous suspension procaine penicillin G (300,000 IU/ml) IM at a dosage of 22,000 IU/kg of body weight (15.4 mg of penicillin G/kg). Serum, synovial fluid, peritoneal fluid, and urine penicillin concentrations were measured serially over a 48-hour period. The mean peak serum penicillin concentration was 1.42 microgram/ml at 3 hours. Penicillin was detected in synovial fluid and peritoneal fluid, which obtained mean peak penicillin concentrations of 0.62 microgram/ml and 0.58 microgram/ml, at 4 hours and 3 hours, respectively. These concentrations ste...
Dunn HO, Smiley D, Duncan JR, McEntee K.The karyotypes of a Welsh pony and a Standardbred were 64,XX/64,XY and 63,XO/64,XY respectively. Both intersexes were true hermaphrodites with bilateral ovotestes. Neither intersex showed stallion-like behaviour. Each one had an underdeveloped penis, bilateral seminal vesicles and uterine tissue. It would appear that the chimerism in these equine intersexes resulted from double fertilization or fusion of blastocysts. Mosaicism in the Standardbred is a possibility, resulting from loss of a Y chromosome by anaphase lag in an early embryonic XY cell.
Carakostas MC, Moore WE, Smith JE.Intravascular granulocyte kinetics in 4 healthy horses were determined with chromium-51 as the cell label. The disappearance rate of labeled granulocytes was an exponential function. Mean total blood granulocyte pool (+/- 1 SD) was 5.65 +/- 1.514 X 10(8) granulocytes/kg of body weight, of which 2.71 +/- 0.715 X 10(8) granulocytes/kg were circulating and 2.94 +/- 0.876 X 10(8) granulocytes/kg were marginated along blood vessel walls. The mean disappearance half-life (T1/2) was 10.5 +/- 1.33 hours and the mean granulocyte turnover rate was 8.84 +/- 1.495 X 10(8) granulocytes/kg/day. A granulokin...
McCullagh KG, Silver IA.The historical development of "firing" as a treatment for various complaints in animals and man is followed from the first surviving written account by Vegetius (approximately AD 500) to the present day. Changing concepts as to the mechanism of action of the actual cautery are examined in relation to physiological understanding at various times and conflicting views and evident fallacies are discussed. It is of particular interest that firing of "sinewes" (tendons and ligaments) was expressly forbidden until the 18th century. It is concluded that "firing" is an outmoded practice for which ther...
McGuire TC, Perryman LE, Banks KL.Following the descriptions of immunodeficiencies in horses beginning in 1973, there has been considerable effort to develop methods for differential diagnosis and to determine the cause and prevalence of the disorders. In addition, the equine immunodeficiencies, especially combined immunodeficiency, have been studied from a comparative viewpoint with the goal of finding information applicable to similar diseases of children. Coincident with the development of knowledge about the immunodeficiencies per se, considerable information about several aspects of immunology has been obtained. It is the...
Noonan NE.Adult female dogs or pony mares were subjected to a nonlethal dose of CCl4 (0.5 ml/kg of body weight). Amounts of several plasma enzymes thought to be indicative of hepatic disease were monitored. Plasma enzymes alanine aminotransferase, aspartate aminotransferase (AST), alkaline phosphatase (ALP), arginase, gamma-glutamyltransferase (GGT), and iditol dehydrogenase (ID), as well as total plasma bilirubin, were determined in these animals before and after the administration of the CCl4. In the dog, GGT was not significantly increased, whereas ALP values were increased during days 1 to 6. In the...
Carakostas MC, Moore WE, Smith JE, Johnson D.The functional capacity of the marrow granulocyte reserve (MGR) in 4 adult horses was studied, using 51Cr-labeled leukocytes. The mean increase in the peripheral granulocyte count following injections of etiocholanolone (0.3 mg/kg) was 870 granulocytes/mm3, and the mean increase following prednisolone administration (200 mg) was 5,880 granulocytes/mm3. Etiocholanolone failed to mobilize the MGR and decreased the rate of granulocyte egress from the blood. Prednisolone rapidly mobilized the MGR and markedly decreased the granulocyte specific activity during the first 3 hours after injection.
Nyack B, Morgan JP, Pool R, Meagher D.Osteochondrosis of the shoulder joint in the horse was diagnosed radiographically in 54 shoulders of 38 horses. Clinical signs were those of an intermittent lameness characterized as a swinging leg shoulder lameness with pain elicited by extension, flexion or abduction of the limb. Diagnosis of shoulder lameness was supported by blocking the shoulder joint with local anesthetics. Radiographic changes consisted of: (1) alteration in the contour of the humeral head and glenoid cavity, (2) periarticular osteophyte formation, (3) sclerosis of the subchondral bone, and (4) bone cyst formation. The ...
Mackay RJ, Iverson WO, Merritt AM.A 4-year-old stallion was examined because of a 2-month history of inappetance and weight loss. Diarrhoea had also developed a month before presentation. Abnormal clinical findings were emaciation, diarrhoea, ventral oedema, palpable mesenteric lymph node enlargement and a large mass in the left cranial portion of the abdomen. Significant laboratory findings were anaemia (packed cell volume 0.21 litres/litre), hypoalbuminaemia (16 g/litre) and xylose malabsorption. The horse was euthanased and at necropsy a 10.5 kg pendunculated mass composed of granulation tissue was found within and attached...
Dietz HH.Diagnostic tests in horses showing signs of gastrointestinal diseases are reviewed. The use of rectal exploration is emphasized, and paracentesis as a diagnostic aid is mentioned. Special attention is given to the absorption tests as they are easy to conduct and give a relative measure of the absorptive capability of the intestinal epithelium. Glucose, D(+)-xylose and carbohydrate digestion-absorption tests are compared, and the D(+)-xylose absorption test is preferred because of the univocal curve of absorption (see Figure 1 and 2). The absorption curve in a horse suffering from alimentary ly...
Moore JN, Garner HE, Shapland JE, Hatfield DG.Bacterial endotoxin injected intravenously into conscious ponies produced alterations in cardiopulmonary and gastrointestinal function. Specifically, tachypnoea, dyspnoea, hypoxaemia, colic, lactic acidosis and diarrhoea resulted from administration of 10 micrograms/kg Escherichia coli endotoxin. Pretreatment of the ponies with a potent prostaglandin synthetase inhibitor, flunixin meglumine, prevented these ill effects of endotoxin.
Kelly JD, Webster JH, Griffin DL, Whitlock HV, Martin IC, Gunawan M.A survey was conducted to determine whether benzimidazole resistant populations of equine strongyles are present in New South Wales and north central Victoria; what is their frequency and geographical distribution; which species are involved; and whether different methods of parasite control could be related to the occurrence and frequency of anthelmintic resistant populations. Resistant populations of strongyles were found over wide areas of New South Wales and in north central Victoria. There was no relationship between geographical location and the occurrence of benzimidazole resistance. Th...
Evans JW, Stanfield J, Hoffman LS, Slaussen C.Testes were obtained from 70 colts and stallions and were pooled according to age (4 months to 23 years) to determine the relationship of age to LH/hCG receptor kinetics. The receptor concentration (Rt) increased from 0.069 x 10(-11) M/mg crude membrane fraction (CMF) for the 4-14-month pools to 0.464 x 10(-11) M for the 2-3-year-old pools. A 10-fold increase in testicular size also occurred, and so the total number of receptors per testis was significantly increased. A further increase to 1.237 x 10(-11) M/mg CMF was observed for stallions older than 5 years. No differences in binding affinit...
Arantes JA, Borges AS, Zakia LS, Surette MG, Weese JS, Costa MC, Arroyo LG.Iron is an essential element for all living organisms, including bacteria, as several virulence factors and replication components are influenced by iron concentration. The objective of this study was to determine whether the composition and diversity of the fecal microbiota of adult horses are affected by supplemental dietary iron. Ten clinically healthy horses were randomly divided into a control and an iron-supplemented group ( = 5). The treated group was supplemented with oral ferrous sulphate monohydrate (720 ppm of iron), whereas the control group received 320 ppm of iron daily for 15 d....
Frape DL, Tuck MG, Sutcliffe NH, Jones DB.1. The rate of passage of chromic oxide (Cr) was similar in the pony and rhinoceros. 2. Higher apparent amounts digested were found using 4N-HCl-insoluble ash (AIA) than those determined by Cr, but overall digestibilities were similar for the two species. 3. An abrupt increase in the starch content of the horse diets increased the number of faecal ciliate protozoa. Only when the overall feed intake was increased in horses receiving a high dietary proportion of starch were the numbers depressed. 4. When the rhinoceros received 109 kJ apparent DE per kg bodyweight daily (716 kJ/W0.75 daily) it m...
Skrabalak DS, Cuddy KK, Henion JD.Micro-liquid chromatography-mass spectrometry (micro-LC-MS) was utilized to quantitatively determine betamethasone and its major unconjugated metabolite, 6 beta-hydroxybetamethasone, in equine plasma and urine. The advantage of micro-LC-MS over conventional gas chromatography-mass spectrometry in corticosteroid determination is illustrated and the reliable, steadfast nature of micro-LC-MS is demonstrated through example.
Pfeiffer CJ, Murray MJ, Fainter L.The granular columnar epithelial cell of the equine dorsal large colon has been studied by transmission electron microscopy and X-ray microanalysis. Particular attention was focused on nuclear bodies commonly observed as central clusters of spherical, electron-dense inclusions within the nucleus. Ultrastructural morphology as well as X-ray microanalysis spectra reveal great similarity between colonic nuclear bodies and the numerous small granules of the apical cytoplasm in these epithelial cells. X-ray spectra of these cells were distinct from those of goblet cell mucous granules and mast cell...
The Journal of nutritionSeptember 1, 1991
Volume 121, Issue 9 1462-1469 doi: 10.1093/jn/121.9.1462
Miller-Graber PA, Lawrence LM, Foreman JH, Bump KD, Fisher MG, Kurcz EV.Six conditioned Quarter Horse mares were used in a crossover design to assess the effect of the dietary protein level on intramuscular and hepatic glycogen and lactate, oxygen uptake and blood lactate, pyruvate and free fatty acids. After a 2-wk adaptation period to either a 9.0% (control) or an 18.5% crude protein diet, each horse performed an exercise test. The horses were exercised for 15 min on an 11% grade treadmill at 4.5 m/sec. The exercise test was performed 3-4 h after a meal. Venous, arterial and mixed-venous blood samples were taken simultaneously at rest and during exercise. Muscle...
Pietra M, Guglielmini C, Forni M, Cinotti S.The viscosity of the mucus, its DNA concentration and the size range of the DNA were determined on tracheobronchial samples from 11 horses with lower airway diseases before and after incubation with recombinant human deoxyribonuclease (rhDNase). The horses were divided into two groups on the basis of the cytology of the samples: group A (five horses) with more than 60 per cent neutrophils and group B (six horses) with fewer than 50 per cent neutrophils. The mean mucus viscosity and DNA concentration in the preincubation samples were significantly higher in group A than in group B, and there wa...
Pizzi GLBL, Valente ALS, Rechsteiner SMEF, Bruhn FRP, Cruz LAX, Silva PM, Barbosa AA, Ribeiro PF, Martins CF.This study evaluated the influence of the Body Condition Score (BCS) and subcutaneous fat thickness on the tissue composition of the digital cushion in horses. Sixty mixed breeds of Criollo horses (21 males and 39 females) were sent for slaughter. All animals were submitted to BCS analysis, through visual antemortem evaluation, and then ultrasound evaluation to estimate the subcutaneous fat thickness. Macroscopic analyses of the thoracic and a pelvic limb (weight, volume, and density of the hooves and digital cushions) were performed. In addition, measurements of the area of internal structure...
Goto I, Kamada M, Inaba M, Maede Y.A protein A-hemolytic plaque assay was applied to detect immunoglobulin (Ig)-producing cells in horse peripheral blood, using pokeweed mitogen as a B lymphocyte activator. A maximum number of Ig-secreting cells was obtained when horse peripheral blood lymphocytes were cultured in a medium containing horse serum. The number of Ig-secreting cells in young horses (2 years old) was lower than that in adult horses (6 to 23 years old). In addition, the plaque formation was unchanged from blood samples kept at 4 degrees C for 24 hours, while blood samples kept for 72 hours did not yield plaques. Thes...
Nunamaker DM, Nash RA.To report development, configuration, application, and results of a tapered-sleeve transcortical pin external skeletal fixation device (TSP ESFD) for use on fractures of the distal aspect of the equine limb. Methods: Optimization analysis of a TSP ESFD was carried out with mechanical testing and review of clinical case outcomes. Methods: Cadaveric adult third metacarpal bones (MC3) for mechanical testing; horses (n=7) with severely comminuted proximal (6; P1) or second (1) phalanx fractures. Methods: Mechanical testing of methods for attachment of TSP to the sidebars were tested as well as opt...
Keller SA, Fürst AE, Kircher P, Ringer S, Kuemmerle JM.To report the clinical findings and outcome of locking compression plate (LCP) fixation of tarsal subluxations in horses. Methods: Retrospective case series. Methods: Horses (n = 3) and ponies (2). Methods: All horses and ponies diagnosed with tarsal subluxations and treated with LCP fixation at our institution between 2011 and 2013 were included. Data were collected from the medical records, including all radiographic and computed tomographic (CT) studies and reviewed. Long-term (>1 year) followup examination, including owner interview, and clinical and radiographic examinations were perfo...
Baum B, Hewicker-Trautwein M, Wohlsein P.A 10-year-old Knabstrupper stallion was euthanatized because of severe dyspnea and exercise intolerance. Postmortem examination revealed diffuse severe alveolar emphysema and chronic fibrosing pleuritis of the caudal lung. Parts of both caudal lung lobes were covered with multiple raised firm gray to yellow plaques. Histologically, these areas consisted of circumscribed pleural fibroses and cysts of metaplastic keratinizing squamous epithelium. Immunohistochemistry revealed intense labeling for cytokeratins 5/6 and 10. In addition, caudal lung lobes were severely affected by a chronic partiall...
Shirer HW, Orr JA, Loker JL.To determine if CO2-sensitive airway receptors are important in the control of breathing, CO2 was preferentially loaded into the respiratory airways in conscious ponies. The technique involved adding small amounts of 100% CO2 to either the latter one-third or latter two-thirds of the inspiratory air in an attempt to raise CO2 concentrations in the airway dead space independent of the arterial blood. Arterial blood gas tensions (PCO2 and PO2) and pH, as well as respiratory output (minute volume, tidal volume, and respiratory rate), were measured in a series of 20 experiments on 5 awake ponies. ...
Galuppo LD, Simpson EL, Greenman SL, Dowd JP, Ferraro GL, Meagher DM.To report clinical evaluation of headless compression screws for repair of metacarpal/metatarsal (MC/MT3) condylar fractures in horses. Methods: Retrospective case study. Methods: Racing Thoroughbreds (n=16) with nondisplaced lateral condylar fractures of MC/MT 3. Methods: Medical records (1999-2004) of horses with nondisplaced longitudinal fractures of the lateral condyle of MC/MT3 were reviewed. Pre-operative variables retrieved were: patient age, gender, limb involvement, injury occurrence, fracture length, and width, evidence of palmar comminution and degenerative joint disease, number of ...