Topic:Adult Horses
Adult horses encompass a category of equines that have reached maturity, typically considered to be around five years of age and older. This stage of life is characterized by full physical development and the potential for peak performance in various activities such as riding, racing, and work. Adult horses require specific nutritional, health, and management practices to maintain optimal condition and performance. The study of adult horses covers a range of topics, including physiology, behavior, and the impact of environmental factors on their well-being. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, health management, and performance aspects of adult horses.
Concentration of sodium hyaluronate in serum. A radioassay for sodium hyaluronate using high-affinity binding protein from bovine cartilage has been modified for serum analysis. The accuracy of the method was checked by isotope dilution experiments and by recovery studies with exogenous hyaluronate. The between-assay standard deviation in the determination is 15-20%. The concentration of sodium hyaluronate in healthy adults (blood donors) is in the range of 10 to 100 micrograms/l with a mean value in the order of 30 to 40 micrograms/l. This is a lower concentration than previously reported. The same level was found in young people. Higher...
Choledocholithotripsy in a mare. Obstructive choledocholithiasis in a 12-year-old mare was corrected surgically by choledocholithotripsy. The mare had a history of chronic weight loss, intermittent fever, partial anorexia, jaundice, recurrent abdominal pain, and an abdominal mass palpable per rectum. Values for alkaline phosphatase, bilirubin, gamma-glutamyl transferase, sorbitol dehydrogenase, and bromsulpthalein half-life were increased and bilirubinuria was evident before surgery. Two liver biopsies revealed periportal and portal fibrosis, bile duct proliferation, cholestasis, and variable amounts of hepatocellular necrosi...
Increased daily sperm production in the breeding season of stallions is explained by an elevated population of spermatogonia. Seasonal variation in number of spermatogonia and germ cell degeneration was evaluated to determine which mechanism might explain seasonal differences in daily sperm production per testis (DSP/testis) or per g parenchyma (DSP/g) in stallions. Comparing 28 adult stallions (4 to 20 yr old) in each of the nonbreeding (December-January) and breeding (June-July) seasons, the population of type A spermatogonia was more than two times greater (P less than 0.01) in the breeding season. While the number of type B spermatogonia also was elevated (P less than 0.01) in the breeding season, the number of t...
Reserpine toxicosis in a horse. A single injection of reserpine in an adult horse was believed to induce toxicosis for several days. Clinical signs included erratic, colic-like behavior followed by depression, bradycardia, miosis, ptosis, and paraphimosis. Diarrhea was not observed and may have been due to the effect of xylazine given with the reserpine. The horse was supported with IV fluids and intensive nursing care. Gradual improvement was noted 72 hours after the horse received the drug. Qualitative analysis via high-performance liquid chromatography was positive for reserpine. Methamphetamine is the recommended antidot...
Intimal asteroid bodies in horses: light and electron microscopic observations. The morphology of asteroid bodies in equine arteries is demonstrated by light microscopy as well as by scanning and transmission electron microscopy combined with chemical analysis. Asteroid bodies first occur in horses at four weeks of age in all investigated tissues except the esophagus and always are located in the subendothelial space. The number, shape, ultrastructure and chemical composition of asteroid bodies differ markedly--depending on the age of the horse. Asteroid bodies are round and smooth in foals, but are shaped irregularly and have several projections and marked stratified cal...
Effect of endotoxin administration on body fluid compartments in the horse. Plasma volume, extracellular fluid volume (ECFV), and total body water (TBW) were measured before and after endotoxin (Escherichia coli) administration in 6 conscious adult horses. Evan's blue dye, sodium thiocyanate, and antipyrine were the test substances used to estimate plasma volume, ECFV, and TBW, respectively. Pharmacokinetic analysis of plasma concentration vs time was used to determine changes in body fluid compartments. The pathophysiologic effects of endotoxin were monitored by clinical evaluation, blood chemical changes, and blood gas determinations. All horses became dyspneic with...
Ataxia and weakness associated with fourth ventricle vascular anomalies in two horses. Two adult horses with progressive neurologic signs were examined clinically and at necropsy. Both horses had signs of progressive ataxia and weakness, clinically diagnosed as spinal cord in origin. Differential diagnoses for cervical spinal ataxia in horses included cervical vertebral malformation, equine degenerative myeloencephalopathy, equine herpes-virus-I myeloencephalopathy, and equine protozoal myeloencephalopathy. Necropsy findings in both horses were similar and consisted of a large hematoma in the fourth ventricle, with upward compression of the cerebellum and downward compression of...
Direct current stimulation of bone production in the horse: preliminary study with a “gap healing” model. The effect of a 20-microA direct-current implantable bone growth stimulator (BGS) on bone production with a "gap healing" model in the horse was evaluated. The right and left 4th metatarsal bones (Mt-4) were used in 7 adult horses to create the "gap healing" model. A 4-mm section of the Mt-4 bone was resected bilaterally in each horse. The BGS was surgically placed into the 7 left Mt-4 defects. The 7 right Mt-4 defects served as controls. Six horses survived the 16-week experimental period. Signs of pain, decreased range of limb motion, or lameness was not observed in any animal during the 16 ...
Capacitively coupled electrical stimulation of bone healing in the horse: in vivo study with a Salter type IV osteotomy model with stainless steel surface electrodes. The use of capacitively coupled low-voltage signals for stimulation of osteogenesis has been reported in a variety of animal models. Electrically induced osteogenesis was investigated with a capacitively coupled electric field on a radius (distal-lateral orientation) osteotomy model, in conjunction with internal fixation and postoperative loading. Twelve adult horses of either sex were allotted to 2 groups of 6; 1 group was given electrical stimulation and the other served as controls. A low-voltage high-frequency capacitively coupled electrical signal was locally and continuously applied to t...
[Extrahepatic cholestasis due to pancreas fibrosis in a trotter]. A trotter stallion showing symptoms of emaciation was suspected of disease of the liver associated with cholestasis in view of clinical symptoms (poor appetite, sluggishness, jaundice and oedema) and the results of examination of the blood (increased concentrations of gamma-glutamyl, transpeptidase, sorbitol dehydrogenase, alkaline phosphatase, aspartate aminotransferase and markedly increased conjugated bilirubin). A specimen removed at biopsy of the liver revealed the presence of portal fibrosis and severe cholestasis. At autopsy, it was found that very extensive fibrosis of the pancreas (pr...
Electroencephalographic patterns of clinically normal, sedated, and tranquilized newborn foals and adult horses. To establish a clinically practical procedure for recording the equine EEG, 25 healthy adult horses and 6 newborn foals were used. Recordings were taken with the animals alert and tranquilized, confined in metal stocks, or physically restrained. The dominant alert waveforms of adult horses were fast activity (25 to 40 Hz) with medium-to-low voltages (5 to 40 microV-dominant 10 to 15 microV). Underlying this fast activity was slower (0.5 to 4.0 Hz) activity with medium-to-low voltages (10 to 40 microV). Twelve of the 25 adult horses had EEG frequencies in the alpha frequency range (10 to 15 Hz,...
Evaluation of a technique for measurement of gamma-glutamyltranspeptidase in equine urine. gamma-Glutamyltranspeptidase (GGT) activity in equine urine was measured, using an assay developed for use with serum and was found to be reproducible. The GGT activity was measured in samples prepared by serial dilution of exogenous GGT with equine urine, and the activity was determined to be linear between 21 IU/L and 407 IU/L. The behavior of exogenously added GGT was compared in equine serum and urine. The enzyme behaved similarly in both fluids. The GGT activity was measured in serum and urine samples after storage at -20, 4, and 25 C for 24 and/or 72 hours. Enzyme activity decreased afte...
Isolation of Streptococcus pneumoniae type 3 from equine species. Streptococcus pneumoniae type 3 was isolated from seven tracheobronchial aspirates and one pleural tap of seven adult horses and one foal. There was no direct evidence in these horses that isolation of the pneumococcus was related to a specific disease syndrome. Presenting complaints included two horses with chronic cough, two horses with decreased exercise tolerance, one horse with exercise-induced pulmonary hemorrhage, and three horses with pneumonia. Antibiotic therapy resolved the primary clinical complaint. This is the first report of the isolation of S. pneumoniae type 3 from adult horse...
Renal clearance and fractional excretion of electrolytes over a 24-hour period in horses. Four consecutive 6-hour urine collections were obtained from 10 healthy adult horses given free access to a complete pelleted ration and water. Samples of blood were collected from the jugular vein at the start of the test period and then every 6 hours for 4 consecutive samples. Mean renal clearance of creatinine (CCr) varied significantly during the four, 6-hour collections, ranging from 1.474 in period II to 2.702 ml/min/kg of body weight during period III (P less than 0.05). The CCr in period III was significantly different from the 24-hour mean value of 1.877 ml/min/kg (P less than 0.05). ...
Castration of horses and donkeys with first intention healing. A simple technique for castration of adult horses which results in first intention healing was devised. The technique involves a 'closed' castration with or without a transfixed ligature on the spermatic sac and suturing the scrotal skin with polyglycolic acid suture material. The postoperative course was characterised by mild oedema only and by rapid recovery. The results obtained during the course of removing 311 scrotal testes from horses and donkeys of all ages are described and discussed. The technique is readily applicable in the field.
Attachment of E. coli-bearing K88 antigen to equine brush-border membranes. Equine small intestinal brush-border membranes, from 40 adult horses were tested in vitro for the presence of receptors for the Escherichia coli adhesive antigens K88ab, K88ac and K99. Only K88-positive strains of E. coli adhered strongly to horse brush-border membranes. In contrast, a K88-negative mutant strain J2, 2 K99-positive strains and 3 E. coli strains isolated from foals failed to adhere to horse brush-border membranes. Purified K88ac pili when reacted with equine brush-border membranes inhibited to a great extent the adhesion of K88-positive E. coli. Similarly, K88-positive E. coli p...
Observations on structure and function of the equine mitral valve. The anatomy of the equine mitral valve and certain variations observed in 60 adult horses are described. The functional role of this valve, sited between the left atrium and the high pressure-generating left ventricle, is discussed in relation to its anatomical structure. A method of examining the left side of the heart post mortem is described.
The prevalence and intensity of internal parasites of horses in the U.S.A. Fifty-five adult horses were necropsied over a 15-month period, and their worm burdens counted and speciated. Twenty-one species of Cyathostominae were recovered. Ten species: Cyathostomum catinatum, Cylicocyclus nassatus, Cylicostephanus longibursatus, Cyathostomum coronatum, Cylicostephanus goldi, C. calicatus, C. minutus, Cylicocyclus leptostomus, C. insigne and Cyathostomum pateratum, comprised 98.9% of the total cyathostome burdens. These same 10 species also demonstrated high prevalences in 4 previous surveys. Eight of these 10 species have been shown to be resistant to benzimidazole ant...
Arterial oxygen and carbon dioxide tensions in conscious laterally recumbent ponies. Six adult ponies were trained calmly to assume and maintain left lateral recumbency without the use of sedative or immobilising agents. During a 30 min recumbent period, pHa, arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2) and heart and respiratory rates were monitored at regular intervals to evaluate ventilatory response. Overall, there were no statistically significant differences found between mean control and recumbent or final standing values. When lightweight ponies were compared to heavyweight ponies, only mean PaO2 at 10 mins recumbency was different. This information supp...
Pathology of maternal genital tract, placenta, and fetus in equine viral arteritis. Six pregnant mares were given equine viral arteritis virus intravenously. Tissues from genital tracts, placentae, and fetuses were examined by light and electron microscopy to study the mechanism of abortion. Four mares which died with acute disease had diffuse vacuolation of endometrial epithelium and systemic necrotizing vasculitis. Two of these mares had dead fetuses and two had live fetuses; virus was isolated from tissues of one live fetus. Placentae of mares dying from acute disease did not have lesions attributable to infection; virus was isolated from two of these placentae. One of the...
Serum concentration of penicillin in the horse after repeated intramuscular injections of procaine penicillin G alone or in combination with benzathine penicillin and/or phenylbutazone. Twenty-one adult horses were randomly assigned into 7 groups of 3 and were treated for 5 days with procaine penicillin G, benzathine penicillin , or phenylbutazone in various combinations and dosage schedules. Serum concentration of penicillin was measured serially over a 7-day period. The highest mean peak serum concentration was 2.06 micrograms/ml. Comparable peak values were seen 2 to 4 hours after administration of 22,000 IU of procaine penicillin G/kg of body weight given once or twice daily. A minimum serum concentration of 0.25 micrograms/ml was selected as adequate for efficacy against...
Continuous caudal epidural anesthesia in the horse. A technique for continuous caudal epidural anesthesia in the horse was developed in trials involving 8 healthy adult horses. The injection site was the first intercaudal (intercoccygeal) space. A Huber point directional needle (Tuohy or Hustead) with a stylet was preplaced into the epidural space, used as a guide for an epidural catheter, and then removed, leaving the catheter in situ in the epidural space. A 2% solution of lidocaine hydrochloride was used as the anesthetic agent at an initial dose of 8 ml for an adult animal (474 kg to 560 kg). Repeated 4-ml doses were administered immediatel...
Chloramphenicol sodium succinate in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intravenous administration. Six healthy adult mares were given a single IV dose (25 mg/kg of body weight) of chloramphenicol sodium succinate. Chloramphenicol concentrations in serum, synovial fluid, peritoneal fluid, and urine were measured serially over a 48-hour period. The highest measured serum chloramphenicol concentration was 6.21 micrograms/ml at 0.5 hour. Chloramphenicol was detected in synovial and peritoneal fluids, with mean peak concentrations of 3.89 micrograms/ml and 3.50 micrograms/ml, respectively, at 0.5 hour. Serum and synovial concentrations declined rapidly and were not measurable at 3 hours. Chloram...
Measurement of plasma antithrombin III activity in healthy horses. A fluorometric assay was used to determine plasma antithrombin III (AT III) activities in 15 healthy adult horses. Nearly all plasma samples had an initial value of greater than 100% thrombin inhibited, so a 1:1 dilution of the prepared samples was performed. Following dilution, the mean value of the animals was 59.17 +/- 7.4% thrombin inhibited. Mares had significantly greater AT III activity than did geldings (P less than 0.01). The results of this study indicate the horse has more AT III activity than did other domestic species in which AT III activity has been reported.
Hyperglycemia and hypoinsulinemia during xylazine-ketamine anesthesia in Thoroughbred horses. Plasma glucose and serum insulin concentrations in Thoroughbreds administered xylazine hydrochloride (1.1 mg/kg; IV) and ketamine hydrochloride (2.2 mg/kg; IV) at dosages sufficient to induce short periods of recumbency and anesthesia were measured. Samples of blood were collected from 6 adult horses before, during, and after the anesthetic period. Plasma glucose (mg/dl) was significantly increased above control (-30 minute concentration) from 15 to 150 minutes after xylazine administration with the peak value occurring at 30 minutes. Serum insulin (microU/ml) was significantly decreased from ...
Reduction of the red blood cell mass of horses: toxic effect of heparin anticoagulant therapy. This study was designed to test the efficacy of heparin anticoagulant therapy in the horse and its effect on the formed elements of blood. Nine clinically normal, nontraumatized adult horses were subjected to 4 different heparin maintenance regimens (dosages of 320, 240, 160, and 40 U/kg of body weight). Porcine intestinal mucosa heparin (20,000 U/ml) was injected subcutaneously every 12 hours for 96 hours (total 9 times). A loading dose of one-third the maintenance dose was given IV just before the first heparin injection. Three control horses were given an equivalent volume of 0.9% saline so...