"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.
Pedersoli WM, Belmonte A, Purohit RC, Ravis WR.The pharmacokinetics of gentamicin were studied in six healthy mature horses of mixed breeding and of both sexes. A parenteral preparation of gentamicin sulfate (5% aqueous solution) was administered rapidly (IV) at the dosage level of 5 mg/kg of body weight. Venous blood samples were taken at 0 (base line), 0.083, 0.25, 0.5, 0.75, 1, 2, 4, 8, 12, 24, 36, 48, 72, 96, and 120 hours after gentamicin administration. Serum gentamicin was measured by a radioimmunoassay technique. The gentamicin concentration data was fitted to a one- and two-compartment open model with first-order elimination from ...
McCool CJ, Gilfedder J.This study explores a rare case where an equine disease was found to be caused by Salmonella anatum, an organism typically associated with cattle, in a week-old foal and its […]
Squires EL, Hillman RB, Pickett BW, Nett TM.Thirty-two light-horse mares were confirmed to be pregnant and assigned to one of four treatments: (1) injected with 250 micrograms of Equimate on day 70 and again on day 77 if abortion had not occurred; (2) injected with 250 micrograms of Equimate on day 70 and every 24 hr until abortion occurred (maximum four injections); (3) injected with 250 micrograms of Equimate on day 70 and every 12 hr until abortion (maximum eight injections); and (4) injected with 250 micrograms of Equimate once only on day 35 of gestation. Mares were observed four times daily for incidence of abortion or side effect...
Snow DH, Guy PS.Skeletal muscle of the equine was differentiated into three fibre types according to myosin ATPase (pH 9.4) and succinic dehydrogenase activity. The percentage of these types was determined in the musculus deltoideus, m triceps brachii caput longum, m gluteus medius, m semitendinosis, m biceps femoris and m vastus lateralis of the thoroughbred, Shetland pony, pony, heavy hunter and donkey. In addition the m gluteus medius was examined in the arab and American racing quarterhorse. High myosin ATPase activity fibres varied from a mean of 93.2 per cent in the m gluteus medius of the quarterhorse ...
Vibe-Petersen G, Nielsen K.Over a period of approx. 3 years, electrocardiograms (ECG) were recorded from 138 horses referred as patients to the Medical Clinic. Of these, 22 horses (approx. 16 per cent) has ECG alterations. The 22 ECG's revealed a total of 29 ECG abnormalities. The most frequent ECG alteration was incomplete AV block, that was seen in 9 horses (31 per cent of the ECG abnormalities). Abnormal (i.e. broad, tent-like and, sometimes, inverted) T waves and deviations of the ST segment were seen each in 5 ECG's from 7 horses, 3 of which had both abnormalities which were associated with severe underlying diseas...
Sheahan BJ, Atkins GJ, Russell RJ, O'Connor JP.Two aged mares with histiolymphocytic lymphosarcoma had multiple rapidly proliferating tumours in the subcutis. Consistent haematological changes were absent. One mare had lymph node involvement but no neoplastic lesions in the viscera. Microbiological examination of tumour tissue showed coryneform bacteria; there was no evidence of C-type or lytic viruses or of reverse transcriptase. Prominent intramitochondrial crystalline inclusions were in histiocytic tumour cells.
Murch KM.Clinical findings, surgical repair and postsurgical care of a unilateral fracture of the mandible of a bull and of a bilateral mandibular fracture in a horse are described. Compression plating limited the pain suffered by the animals and resulted in a quick return to function of the mandibles.
Liefman CE.The protection afforded by active, passive and combined active-passive methods of immunisation against tetanus was examined in previously unimmunised horses. Three groups of horses were injected; one with tetanus toxoid alone, one with tetanus antitoxin alone and one in which the tetanus toxoid and tetanus antitoxin were injected simultaneously. The protection afforded was determined by monitoring the levels of antitoxin achieved in the horses by each of these methods. The results obtained demonstrated the effectiveness of the combined active-passive method in affording rapid and prolonged pro...
Timoney PJ.The usefulness of the double immunodiffusion test for the diagnosis of louping ill infection was investigated. Whereas louping ill viral antigen was not detected in brain material from field cases of the infection, its presence was readily confirmed in suckling mouse brain isolates of the virus. The double immunodiffusion test was found to be unreliable as a serological test for the retrospective diagnosis of louping ill infection in the horse.
Freeman DE, Donawick WJ.An intravascular procedure was used to occlude the internal carotid artery of two horses with epistaxis caused by guttural pouch mycosis. In each horse, the affected internal carotid artery was ligated close to its origin. A balloon-tipped catheter was introduced into the artery distal to the ligature, and its tip was advanced beyond the site of infection. The balloon was then inflated so that the infected segment of artery was isolated from the cerebral vascular system. The catheters were removed at 14 and 51 days, and both horses were returned to training and racing. Neither horse had furthe...
Swerczek TW.Toxicoinfectious botulism was proved to be the cause of a neuromuscular paralytic syndrome in foals and adult horses. In eight successive cases, Clostridium botulinum type B was isolated at necropsy. Foals were either found dead without premonitory signs of illness or, most often, they had signs of progressive and symmetric motor paralysis. Stilted gait, muscular tremors, and the inability to stand longer than 4 to 5 minutes were the salient clinical signs. Other clinical manifestations included dysphagia, constipation, mydriasis, and frequent urination. As the disease progressed, dyspnea with...
Stick JA.In three horses with abdominally retained testicles, teratomas with cyst formation were found. Bone development in the head of the epididymis, near the vascular supply of the tumor, was a consistent finding. Aspiration of the cystic portion of the tumor was necessary for surgical removal in two cases. Although germinal carcinoma cells have been suggested as the cause of teratomas, evidence of malignancy was not seen in any of the three tumors.
Stick JA, Wilson T, Kunze D.Of three horses with basilar skull fractures, two died within 48 hours. The remaining horse was euthanatized because of a locomotion deficit. Clinical signs included epistaxis followed by ataxia. In each case, the basi-occipital bone and ventral portion of the calvarium were involved in the fracture. Diagnosis was based on clinical signs or radiographic appearance of guttural pouches, or both.
Wheat JD, Pascoe JR.Problems involving the management of acute traumatic rupture of the equine suspensory apparatus include loss of blood flow to the foot, proper immobilization, and pressure sores from casts. A technique utilizing a board splinting device attached to the affected limb at the toe and subsequent corrective shoe support provides immobilization, prevents dropping of the fetlock, can be applied to the standing animal, and allows frequent changing of the bandages, if necessary.
Sivertsen T.Reduced glutathione (GSH), per cent methaemoglobin and haemolysis were measured in physiologic saline suspensions of erythrocytes from sheep, goat, cattle, horse, swine and man; incubated for 24 hours at 37 degrees with and without copper sulphate (0,5 and 10 micrograms Cu/ml suspension). Formation of Heinz bodies was studied in similar experiments with sheep and swine cells only. Generally, GSH depletion developed first, followed by methaemoglobinemia and Heinz bodies, while haemolysis was limited. Both spontaneous and copper-induced GSH depletion was slow in swine erythrocytes compared to ot...
Smith BP, Timm K, Jahn S, Reina-Guerra M.Three of 33 ponies died after the herd had been moved to a new environment 3 months earlier. One mare died without premonitory signs of illness. Shortly thereafter, a 5-day-old foal and a 2-year-old gelding died after brief illness. Although cultures were not performed on the mare, Salmonella typhimurium was isolated from the feces and tissues of the foal and gelding. Lesions in the foal were confined to ecchymotic hemorrhages on the mucosal surface of the colon and petechial hemorrhages in the splenic capsule, with adhesions to the parietal peritoneum. The gelding had evidence of severe typhl...
Bowman SG, Marshall JF, Blikslager AT.To determine demographic characteristics of horses donated to the North Carolina State University Equine Health Center (EHC) between 1996 and 2008. Methods: Retrospective cohort study. Methods: 122 horses donated to the EHC between January 1996 and December 2008, and 246 horses offered for donation to the EHC between January 2007 and December 2008. Methods: Telephone and medical records were examined. Data were collected in 5 categories: age, sex, breed, reason for donation, and use prior to donation. Results: From January 1996 through December 2008, 122 horses were donated to the EHC (median,...
Grubb TL, Constable PD, Benson GJ, Foreman JH, Olson WO, Thurmon JC, Tranquilli WJ, Davis LE.To determine the most repeatable method for evaluating right ventricular relaxation rate in horses and to determine and compare effects of isoflurane or halothane with and without the added influence of intravenously administered calcium gluconate on right ventricular relaxation rates in horses. Methods: 6 Thoroughbred horses from 2 to 4 years old. Methods: 6 models (2 for monoexponential decay with zero asymptote, 3 for monoexponential decay with variable asymptote, and 1 for biexponential decay) for determining right ventricular relaxation rate were assessed in conscious and anesthetized hor...
Braun JP, Carstensen CA.Potassium concentrations were measured in the plasma of 336 animals with a new reagent carrier (Reflotron; Boehringer Mannheim) K+ and with an ion-specific electrode system: results were highly correlated (r = 0.991; y = 0.993 x + 0.02) and day-to-day coefficient of variation of the new reagent measurements was lower than 2.5 per cent. This system offers a good alternative to the ion-selective electrode system for plasma potassium measurement in veterinary practice.
McKenzie EC, Firshman AM.Chronic exertional rhabdomyolysis represents a syndrome of recurrent exercise-associated muscle damage in horses that arises from a variety of etiologies. Major advances have been made in the understanding of the pathophysiology of this disease, and causative genetic defects have been recently identified for two conditions-polysaccharide storage myopathy of quarter horses, paints, warm bloods, and draft breeds. Dietary management in combination with a regular exercise regimen comprises the most effective means for control of clinical signs.
Dik KJ.Common soft tissue disorders of the equine carpus are fluctuating or firm soft tissue swellings, wounds and draining tracts. Survey radiography may show the size, position and origin of the swellings and reveals soft tissue calcification, accumulation of air and radiopaque foreign material. Contrast radiography enables accurate visualization of the size, shape, position and origin of fluctuating soft tissue swellings, demonstrates abnormal intersynovial communication and allows precise demonstration of the extent of puncture wounds and draining tracts. Ultrasonography allows differentiation be...
Newton-Clarke MJ, Divers TJ, Valentine BA.A study was conducted over a 12 month period to assess the accuracy of the 'slap test' in the diagnosis of laryngeal adductor myopathy. The thoraco-laryngeal reflexes of 15 horses with no clinical signs of idiopathic laryngeal hemiplegia (ILH) were recorded using a video-endoscope. These 'slap test' responses were examined independently by 3 assessors. The horses were subsequently subjected to euthanasia and samples taken from the cricoarytenoideus lateralis (CAL) muscles for histopathological examination and assessment of denervation atrophy. Despite normal adductory responses, moderate to se...
Orsini JA, Wrigley J, Riley P.Home care for horses with chronic laminitis has been discussed rarely in the veterinary literature even though, at any given time, most of us have at least 1 chronic laminitis case in our care that is being managed at home by the owner. Almost all of our knowledge on this aspect of laminitis treatment has been gleaned through experience, by individually working through the medical, ethical, financial, and emotional challenges these cases can present. Much has already been presented on the medical management of the laminitic horse and on strategies for trimming and shoeing the laminitic foot. T...
Madison JB, Ziemer EL.Purified streptococcal M protein was injected into one intercarpal joint in three horses hyperimmunised with Streptococcus equi M protein vaccine. The contralateral joints were injected with pH adjusted polyionic solution. All antigen-injected joints developed a severe suppurative synovitis (mean synovial fluid nucleated cell count = 102,200 x 10(6) cells litre-1). Eosinophils were found in the synovial fluid and in synovial membrane biopsy specimens of two of the horses. Immune complexes were not demonstrated in the synovial membrane. Two horses are described that developed synovial fluid eos...
Lynch JA.A Staphylococcus aureus infection in a mature horse, resulting from trauma, is described, which proved refractory to antibiotic therapy directed by the results of antibiotic sensitivity testing. After a prolonged course, rapid resolution of the infection was achieved with the administration of an autogenous formalized bacterin.
Lindsey AC, Bruemmer JE, Squires EL.Mares are generally inseminated with 500 million progressively motile fresh sperm and approximately 1 billion total sperms that have been cooled or frozen. Development of techniques for low dose insemination would allow one to increase the number of mares that could be bred, utilize stallions with poor semen quality, extend the use of frozen semen, breed mares with sexed semen and perhaps reduce the incidence of post-breeding endometritis. Three low dose insemination techniques that have been reported include: surgical oviductal insemination, deep uterine insemination and hysteroscopic insemin...
Gelberg HB, McEntee K.Interstitial cell tumors from nine stallions were described. In all but one horse the tumors were found in undescended testes. Five animals had bilateral tumors. Two animals showed increased aggression. Tumors contained two cell types. The first type were large distinctly bordered eosinophilic cells interpreted to be hyperplastic and hypertrophic interstitial cells. They blended with pleomorphic often spindloid neoplastic cells which had fibrillar, vacuolated cytoplasm and indistinct cell borders. This latter cell population was arranged in nodules or broad sheets as endocrine-like packets or ...
Rogerson BA, Condron RJ, Baker J, Craven JA.Inoculation of Haemophilus equigenitalis into the uterus of 7 mares caused a disease clinically indistinguishable from contagious equine metritis. The duration of clinical signs varied from 4 to 11 days. The causative organism persisted for a relatively short time (2 to 10 weeks) in 5 mares, but in 2 others it established a carrier status and persisted until they were killed 6 and 10 months after infection. H. equigenitalis was recovered from the vestibule of the vagina and from a combined swab of the clitoral fossa and sinuses throughout the course of the infection. In some mares there were e...
Taylor PM.The study investigated whether hypotension in halothane-anaesthetised ponies is the stimulus inducing an endocrine stress response by assessing the effect of maintenance of normotension with a dobutamine infusion. Groups of six ponies were studied. After premedication with acepromazine (0.04 mg/kg) anaesthesia was induced with thiopentone (10 mg/kg) and maintained for 120 min with halothane (group AN). Dobutamine was infused to effect (1.1-4.4 microg/kg/min) to maintain arterial pressure at pre anaesthetic levels. The conscious group (CON) were prepared as for AN and then received only dobutam...
Manohar M, Goetz TE, Nganwa D.Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below tha...
Sirois J, Betteridge KJ, Brault A.Embryo transfer was used in an equestrian teaching center in order to produce as many foals as possible from their preferred mares during a single breeding season. Embryo collection by uterine lavage was attempted in five donor mares on 25 occasions 6.5 days after ovulation. Sixteen of the collection attempts (64%) yielded a total of 17 blastocysts. Of these 17 embryos, 13 were immediately transferred transcervically into recipient mares that had ovulated within two days of the time of ovulation in the donors, three were frozen for later transfer, and one was lost. Eight of the freshly transfe...
Díaz-Espiñeira M, Escolar E, Bellanato J, Rodriguez M.The secondary constituents accompanying calcite and vaterite (crystalline forms of calcium carbonate) in the sabulous deposits from 140 vesical samples and one renal sample of equine urine were studied by infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Apatitic calcium phosphate, present in 12 per cent of the samples, generally appeared in the form of spherulites with smooth and rough surfaces. Calcium sulphate, clearly detected by IR in 12.7 per cent of the samples, did not have a characteristic structure under SEM, although EDX detec...
Bartels JE, Beckett SD, Brown BG.Serial arteriography was used to determine the vascular pattern and blood flow in the penis of the pony stallion. Ponies were anesthetized with pentobarbital sodium, and catheters were surgically introduced into the internal pudendal and obturator arteries. The vascular anatomy was visualized by angiography via image-intensified fluoroscopy and was recorded on 70-mm film at 3 frames/s or by direct radiography. Blood flow into the corpus cavernosum penis (CCP) was limited during quiescence because the blood was immediately shunted into the venous system. After vasodilation with mild stimulation...
