The physiology of horses encompasses the study of the biological functions and processes that occur within the equine body. This includes the examination of various systems such as the cardiovascular, respiratory, musculoskeletal, digestive, and nervous systems. Understanding equine physiology is essential for comprehending how horses adapt to different environmental conditions, perform physical activities, and respond to health challenges. Research in this field often focuses on the mechanisms of energy metabolism, thermoregulation, and muscle function during exercise, as well as the physiological responses to stress and disease. This page compiles peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine physiology, providing insights into the biological processes that support the health and performance of horses.
Dutto DJ, Hoyt DF, Cogger EA, Wickler SJ.Although the forces required to support the body mass are not elevated when moving up an incline, kinematic studies, in vivo tendon and bone studies and kinetic studies suggest there is a shift in forces from the fore- to the hindlimbs in quadrupeds. However, there are no whole-animal kinetic measurements of incline locomotion. Based on previous related research, we hypothesized that there would be a shift in forces to the hindlimb. The present study measured the force produced by the fore- and hindlimbs of horses while trotting over a range of speeds (2.5 to 5 m s(-1)) on both level and up an...
Sanchez LC, Murray MJ, Merritt AM.To evaluate the efficacy of omeprazole paste, a commonly used antiulcer drug, on intragastric pH in clinically normal neonatal foals. Methods: 6 clinically normal foals between 5 and 14 days of age. Methods: Intragastric pH was recorded in each foal by use of a disposable antimony pH electrode with internal reference. Values for intragastric pH were recorded every 4 seconds by use of an ambulatory pH monitor. There were two 24-hour recordings of intragastric pH for each foal, with 24 hours between recordings. Foals were not administered any drugs during the first recording. Foals were administ...
Brosnan RJ, LeCouteur RA, Steffey EP, Imai A, Farver TB.To determine whether high intracranial pressure (ICP) during spontaneous ventilation (SV) in anesthetized horses coincides with an increase in intracranial elastance (ie, change in ICP per unit change of intracranial volume). Methods: 6 adult horses. Methods: Anesthesia was induced and maintained in each horse for 5 hours with isoflurane at a constant dose equal to 1.2 times the minimum alveolar concentration. Direct ICP measurements were obtained by use of a strain gauge transducer inserted in the subarachnoid space, and arterial blood pressure was measured from a carotid artery. Physiologic ...
Piccione G, Bertolucci C, Foà A, Caola G.The hormone leptin is secreted by white adipocytes and regulates food intake and energy expenditure in rodents and humans. The goal of the present study was to investigate the existence of a daily rhythm of serum leptin in horses and its dependence on fasting and physical exercise. A robust daily rhythm of leptin was found in both athletic and sedentary horses, with a daytime trough and a peak in the dark phase. While physical exercise never induced changes in circulating leptin, fasting reliably affected serum leptin levels. Food deprivation did not abolish the daily rhythm of serum leptin, b...
Watson ED, Bae SE, Thomassen R, Thomson SR, Woad K, Armstrong DG.The period between seasonal anoestrus and cyclicity is characterized in many mares by cyclical growth and regression of large dominant follicles. The insulin-like growth factor (IGF) system plays a key role in follicular growth and regression; therefore, we hypothesized that changes in the IGF system and its binding proteins would modulate onset of cyclicity in mares. Ovaries were obtained from pony mares on the day after detection of an actively growing 30 mm transitional anovulatory follicle, and also at the second or third oestrus of the breeding season on the day after the preovulatory fol...
Campbell ML, England GC.Uterine motility may have significance for the transportation of spermatozoa and the elimination of the ejaculate and inflammatory products after mares have been covered. The effect of some of the component stimuli of coitus on uterine contractions was investigated by using M-mode ultrasound. The number, amplitude and duration of the uterine contractions of each uterine horn and of the uterine body were measured in oestrous mares for four minutes before and four minutes after teasing by a stallion, mechanical stimulation of the vagina and cervix, the intrauterine infusion of 80 ml of sterile s...
Luo J, Bruice TC.Molecular dynamics and cross-correlation analysis of the horse liver alcohol dehydrogenase HLADH.NAD(+).PhCH(2)O(-) complex has established anticorrelated motions between the NAD(+)-binding domain and other portions of the enzyme. Four pairs of anticorrelated interactions are (i and ii) cofactor-binding domain: C(alpha) of V292 and the CG1 of V203 with C7 of PhCH(2)O(-); (iii) cofactor-binding domain: amide carbonyl oxygen of I318 with amide N of H67; and (iv) cofactor domain: C(alpha) of T178 with carbonyl oxygen of L141. The average distances between pairs are 9.2 A for i, 8.2 A for ii, 14.7...
van der Harst MR, Brama PA, van de Lest CH, Kiers GH, DeGroot J, van Weeren PR.In articular joints, the forces generated by locomotion are absorbed by the whole of cartilage, subchondral bone and underlying trabecular bone. The objective of this study is to test the hypothesis that regional differences in joint loading are related to clear and interrelated differences in the composition of the extracellular matrix (ECM) of all three weight-bearing constituents. Methods: Cartilage, subchondral- and trabecular bone samples from two differently loaded sites (site 1, dorsal joint margin; site 2, central area) of the proximal articular surface of 30 macroscopically normal equ...
Sellon DC, Roberts MC, Blikslager AT, Ulibarri C, Papich MG.A randomized, controlled, blinded clinical trial was performed to determine whether butorphanol administered by continuous rate infusion (CRI) for 24 hours after abdominal surgery would decrease pain and surgical stress responses and improve recovery in horses. Thirty-one horses undergoing exploratory celiotomy for abdominal pain were randomly assigned to receive butorphanol CRI (13 microg/kg/h for 24 hours after surgery; treatment) or isotonic saline (control). All horses received flunixin meglumine (1.1 mg/kg IV q12h). There were no significant differences between treatment and control horse...
Saulez MN, Cebra CK, Tornquist SJ.Alkaline phosphatase (ALP) is an enzyme present in intestinal mucosa, bile, bone, and renal tubule cells. We sought to assess the diagnostic and prognostic relationships of total ALP (ALPt) activity and that of intestine-derived ALP (ALPi) in serum and peritoneal fluid of 126 horses with colic. ALPt and ALPi activities were measured in both serum and peritoneal fluid by using both standard and L-phenylalanine-based buffers, respectively. Neither ALPt nor ALPi activity were useful in classifying type or severity of intestinal damage. ALPt and ALPi activities in peritoneal fluid were lowest in h...
Sessions DR, Reedy SE, Vick MM, Murphy BA, Fitzgerald BP.Peripheral insulin resistance is the failure of proper cellular glucose uptake in response to insulin. Insulin resistance and hyperinsulinemia are associated with several disease states in the horse and reproductive function disturbances in humans, including polycystic ovarian syndrome. To test the hypothesis that insulin resistance (IR) and hyperinsulinemia disrupt the estrous cycle in mares, two experiments were conducted to first develop a model to induce IR and to then examine the effect of this model on the duration of the estrous cycle. In Exp. 1, a hyperinsulinemic-euglycemic clamp (HEC...
Hiney KM, Nielsen BD, Rosenstein D.The hypothesis that short-duration exercise may ameliorate the decrease in bone mass observed with confinement was investigated with 18 quarter horses (nine colts and nine fillies) weaned at 4 mo of age and placed into box stalls. After a 5-wk adjustment period, individuals were grouped by age and weight, and then divided randomly into three treatment groups: 1) group housed; 2) confined with no exercise; and 3) confined with exercise. The confined and exercised groups were housed in 3.7 m x 3.7 m box stalls for the 56-d duration of the trial. The exercised group was sprinted 82 m/d, 5 d/wk, i...
Aleman M, Riehl J, Aldridge BM, Lecouteur RA, Stott JL, Pessah IN.Equine malignant hyperthermia MH has been suspected but never genetically confirmed. In this study, we investigated whether mutations in a candidate gene, RyR1, were associated with MH in two clinically affected horses. RyR1 gene sequences revealed polymorphisms in exons 15, 17, and 46 in WTRyR1 and MHRyR1 horses with one derived amino acid change in MHRyR1 exon 46, R2454G. The MHRyR1 horses were genetically heterozygous for this mutation, but presented an MH phenotype with halothane challenge. Skeletal sarcoplasmic reticulum from a R2454G heterozygote collected during a fulminant MH episode s...
Rietmann TR, Staﾬher M, Bernasconi P, Auer JA, Weishaupt MA.The objective of this study was to compare the stress response of horses suffering from laminitis after short- and long-term treatment with the intent to evaluate power spectral analysis of heart rate variability (HRV) for pain monitoring. Data were collected from 19 horses with acute or chronic exacerbating laminitis without known primary disease before and after treatment with non-steroidal anti-inflammatory drugs (NSAID). Recordings were carried out the day after admission to the equine hospital. Measurements were repeated on day 7 of the treatment. The recorded parameters included a clinic...
Bowen IM, Marr CM, Chester AH, Wheeler-Jones CP, Elliott J.The equine aortic valve is subject to non-inflammatory degenerative changes, associated with aortic valvular regurgitation (AR). This disease shares pathological and epidemiological features with AR in humans, and may serve as a useful model to study in-vitro functional responses associated with aging and disease. The study aim was to determine the contractile properties of the normal equine aortic valve. Methods: The contractile responses of equine aortic valves to angiotensin II, the thromboxane-mimetic U44069, endothelin-1, 5-hydroxytryptamine and the alpha-adrenoceptor agonists medetomidin...
Plasenzotti R, Stoiber B, Posch M, Windberger U.Comparative animal studies showed the wide variation of whole blood and plasma viscosity, and erythrocyte aggregation among mammalian species. Whole blood viscosity and red blood cell aggregation is influenced by red cell fluidity. To evaluate differences in erythrocyte deformability in mammals, three species were investigated, whose erythrocytes have a different aggregation property: horse, as a species with high, dog with medium, and sheep with almost unmeasurable aggregation tendency. Erythrocyte deformability was tested ektacytometrically (Elongation Index [EI], LORCA, Mechatronics, Hoorn,...
Hirst SJ, Martin JG, Bonacci JV, Chan V, Fixman ED, Hamid QA, Herszberg B, Lavoie JP, McVicker CG, Moir LM, Nguyen TT, Peng Q, Ramos-Barbón D....Increased airway smooth muscle (ASM) mass is perhaps the most important component of the airway wall remodeling process in asthma. Known mediators of ASM proliferation in cell culture models fall into 2 categories: those that activate receptors with intrinsic receptor tyrosine kinase activity and those that have their effects through receptors linked to heterotrimeric guanosine triphosphate-binding proteins. The major candidate signaling pathways activated by ASM mitogens are those dependent on extracellular signal-regulated kinase and phosphoinositide 3'-kinase. Increases in ASM mass may also...
Wessel MT, Ball BA.Osmotic stress is an important component of the damage to spermatozoa during cryopreservation. Osmotic injury, due to hyperosmolar freezing extenders, changes in relative solute concentration in the extra cellular medium during freezing and differences in the relative permeabilities of penetrating cryoprotectants, such as glycerol, and water occur when cryopreserved spermatozoa are diluted into isosmotic media or when spermatozoa are placed in the female reproductive tract. The purpose of the study reported here was to evaluate the effect of step-wise dilution for the removal of the permeating...
Mobasheri A, Trujillo E, Bell S, Carter SD, Clegg PD, Martín-Vasallo P, Marples D.Chondrocytes exist in an unusual and highly variable ionic and osmotic environment in the extracellular matrix of articular cartilage. Alterations to the ionic and osmotic environment of chondrocytes influence the volume and ionic content of the cells, which, in turn, modifies the rate at which extracellular matrix macromolecules are synthesized and degraded. Thus, regulation of the water and solute content of chondrocytes will profoundly affect their anabolic and catabolic functions. The water content of cells is effectively influenced by the abundance of aquaporin (AQP) water channels. Recen...
Squires EL, Keith SL, Graham JK.Although use of cryopreserved stallion spermatozoa is currently accepted by many breed registries, utilization of this technique remains limited due to poor fertility for some stallions. One reason for these results is osmotic stress that spermatozoa experiences when the cryoprotectant (glycerol) is added to the cells prior to freezing and removal from the cells after thawing. In an effort to minimize osmotic damage, alternative cryoprotectants, having lower molecular weights and greater membrane permeability than glycerol, were evaluated to determine their effectiveness for cryopreserving sta...
The Journal of nutritionJuly 31, 2004
Volume 134, Issue 8 Suppl 2133S-2140S doi: 10.1093/jn/134.8.2133S
Marlin DJ, Johnson L, Kingston DA, Smith NC, Deaton CM, Mann S, Heaton P, Van Vugt F, Saunders K, Kydd J, Harris PA.Oxidative stress occurs when antioxidant defense mechanisms are overwhelmed by free radicals and may lead to DNA damage, which has been implicated in processes such as aging and diseases such as cancer. The two main techniques presently used to quantify DNA damage are measurement of 8-hydroxydeoxyguanosine and the Comet assay (also known as single-cell gel electrophoresis). The aim of this study was to apply the comet assay to equine peripheral blood mononuclear cells (PBMCs) and identify two conditions in which we hypothesized that oxidative DNA damage would be increased in PBMCs: aging and e...
Lacombe VA, Hinchcliff KW, Kohn CW, Devor ST, Taylor LE.To determine effects of feeding diets with various soluble-carbohydrate (CHO) content on rates of muscle glycogen synthesis after exercise in horses. Methods: 7 fit horses. Methods: In a 3-way crossover study, horses received each of 3 isocaloric diets (a high soluble CHO [HC] diet, a low soluble CHO [LC] diet, or a mixed soluble CHO [MC] diet). For each diet, horses were subjected to glycogen-depleting exercise, followed by feeding of the HC, LC, or MC diet at 8-hour intervals for 72 hours. Results: Feeding the HC diet resulted in a significantly higher glycemic response for 72 hours and sign...
Spadavecchia C, Andersen OK, Arendt-Nielsen L, Spadavecchia L, Doherr M, Schatzmann U.To investigate whether facilitation of the nociceptive withdrawal reflex (NWR) can be evoked and quantified as a measure of temporal summation from the distal aspect of the left forelimb and hind limb in standing nonsedated horses via repeated stimulations of various subthreshold intensities and frequencies. Methods: 10 adult horses. Methods: Surface electromyographic activity evoked by stimulation of the digital palmar and plantar nerves was recorded from the common digital extensor and cranial tibial muscles. For each horse, the NWR threshold intensity to a single stimulus was determined for...
Sutter WW, Kaneps AJ, Bertone AL.To evaluate the buffy coat and apheresis methods for preparation of platelet concentrates from equine blood by comparing platelet and growth factor concentrations. Methods: 15 mature mixed-breed geldings. Methods: Whole blood samples were collected and processed by use of a buffy coat or apheresis method to obtain platelet poor and platelet concentrated fractions. The PCV, WBC count, and platelet count were compared among whole blood samples, platelet poor fractions, concentrates obtained by use of the apheresis method (ie, apheresis platelet concentrates), and concentrates obtained by use of ...
Saint-Dizier M, Chopineau M, Dupont J, Combarnous Y.The full-length equine luteinizing hormone/chorionic gonadotropin (LH/CG) receptor (eLH/CG-RA) cDNA and two alternatively spliced isoforms (eLH/CG-RB,C) were isolated from luteal tissue and characterized using a combination of reverse transcription-polymerase chain reaction (RT-PCR) and 5'-rapid amplification of cDNA ends. The 680-amino acid full sequence of eLH/CG-RA displayed 87-92% homology with other mammalian LH/CG-Rs. The eLH/CG-RB and eLH/CG-RC cDNA isoforms were truncated from the 3'-end of exon X: eLH/CG-RB spliced out of frame into the last exon whereas eLH/CG-RC contained an in-fram...
Gehlen H, Bubeck K, Stadler P.In 12 healthy warmblood horses and 10 horses with mitral valve insufficiencies (MVI) of various degrees heart rate and pulmonary artery wedge pressure (PWP) was measured at rest and during standardised exercise on a high speed treadmill. There was a significant increase in PWP with each change in speed of the treadmill (p < 0.01). The PWP of horses with mild mitral valve regurgitation under working conditions was not significantly different compared to the healthy horses. The horses with moderate mitral valve regurgitation showed a significant higher pulmonary artery wedge pressure at rest and...
Iqbal J, Bird JL, Hollander AP, Bayliss MT.This study was carried out to investigate the effect of two enzymes (collagenase and chondroitinase) and two cytokines/metabolites (interleukin-1beta and retinoic acid) of known catabolic activity on the expression of cartilage metabolism/phenotype in equine articular cartilage. Articular cartilage explants from 11 horses (5-13 years old) were treated for 48 h and assayed for total sulphated glycosaminoglycan (GAG), the incorporation of 35S-sulphate, collagen degradation and mRNA expression of the proteoglycans collagen II, collagen IIA, collagen III, collagen IX, collagen X, collagen XI and g...
Matthews AG.It is conservatively estimated that some form of lens opacity is present in 5% to 7% of horses with otherwise clinically normal eyes.These opacities can range from small epicapsular remnants of the fetal vasculature to dense and extensive cataract. A cataract is defined technically as any opacity or alteration in the optical homogeneity of the lens involving one or more of the following: anterior epithelium, capsule, cortex, or nucleus. In the horse, cataracts rarely involve the entire lens structure (ie, complete cataracts) and are more usually localized to one anatomic landmark or sector of ...
Zollinger A, Wyss C, Bardou D, Bachmann I.In domestic conditions, adult stallions are mostly housed individually in internal stables to reduce the risk of injuries during social interactions. Social deprivation in horses results in physiological stress and behavioural problems. The aim of this study was to test the "social box" (SB), which allows closer physical contact between neighbouring horses. Eight pairs of stallions (n = 16) were filmed over a 24 h period in the SB and in their usual box stables, "conventional boxes" (CB), which strongly restrict tactile contact. The effect of housing in the SB on behaviour and the occurrence a...
Ellington JE, Ball BA, Yang X.The objective of this study was to determine whether coculture of stallion spermatozoa and mare oviductal (uterine tubal) epithelial cells induced sperm cell capacitation in vitro. Capacitation as determined by zona binding and chlortetracycline staining of the sperm cells was compared for stallion spermatozoa: (1) incubated with medium alone (negative control), (2) treated with calcium ionophore A23187 (positive control) or (3) cultured with mare oviductal epithelial cells (OEC) for 4 h. Chlortetracycline staining patterns of sperm cells bound to the zonae were used to group spermatozoa as un...
Hellings IR, Krontveit R, Øverlie M, Kallmyr A, Holm T, Fintl C.Elevated cardiac troponin T (cTnT) concentrations may provide evidence of myocardial injury but physiological post-exercise release also occurs. Reference intervals are not fully established in horses making interpretation difficult. The aims of this study were to establish an upper reference limit for serum cTnT, compare pre-and post-race serum cTnT concentrations, and to evaluate factors that may influence these in a population of healthy, race-fit Standardbred racehorses. Serum samples were collected pre- (n = 108) and 1-2 h post-racing (n = 101) and analysed using a high sensitivity-cTnT a...
Müller AJ, Letelier ME, Galleguillos MA, Molina-Berríos AE, Adarmes HH.To evaluate the antioxidant effects of synovial fluid (SF) pooled from metacarpophalangeal joints of healthy horses and horses with various pathological conditions, and to compare then with the antioxidant effects of hyaluronic acid (HA) and chondroitin sulfate (CS). Methods: SF from 1 metacarpophalangeal joint was obtained from 42 horses immediately after humane slaughter. Samples were classified into 3 groups on the basis of origin: healthy joints or joints with chronically damaged cartilage or vascularly congested synovial membranes as detected via macroscopic evaluation. Methods: Antioxida...
Ousey JC, McArthur AJ, Rossdale PD.Metabolic rates, rectal temperatures and respiratory quotients (RQ) were determined during the first 24 h post partum in Thoroughbred and pony foals and in relation to environmental temperature. Both breeds had high metabolic rates (greater than 200 W/m2) during the first hour post partum when they were wet and shivering; by 4 to 24 h values were fairly steady at about 153 and 105 W/m2 for Thoroughbred and pony foals, respectively. At birth, rectal temperature was lower in Thoroughbred foals than in pony foals; values increased during the first hour, and then decreased. At 24 h of age, both br...
Ginther OJ, Gastal EL, Gastal MO, Beg MA.During a follicular wave in mares, the two largest follicles (F1 and F2) begin to deviate in diameter when F1 is a mean of 22.5 mm. The intrafollicular effects of pregnancy-associated plasma protein-A (PAPP-A), IGF-I, activin-A and vascular endothelial growth factor (VEGF) on other follicular-fluid factors during deviation were studied. In four treated groups (n = 7/group), a single dose of one of the four factors was injected into F2 when F1 was > or = 20.0 mm (expected beginning of deviation). In a control group (n = 7), F2 was injected with vehicle. One day after treatment, a sample of f...
Brandon CI, Vandenplas M, Dookwah H, Murray TF.The aim of this study was to establish a heterologous expression system for the equine adenosine A(3) receptor (eA(3)-R) in an effort to ascertain its pharmacologic profile. Initially, radioligand binding assays identified clones expressing the eA(3)-R in human embryonic kidney cells (HEK) based on the specific binding of [(125)I]AB-MECA. Subsequently, adenylate cyclase assays were utilized to demonstrate functional coupling of the eA(3)-R to the G-protein/adenylate cyclase system. Equilibrium competition binding assays were then performed using selective and non-selective A(3) agonists and an...
Vance SJ, McDonald RE, Cooper A, Kennedy MW, Smith BO.Latherin is an intrinsically surfactant protein of ~23 kDa found in the sweat and saliva of horses. Its function is probably to enhance the translocation of sweat water from the skin to the surface of the pelt for evaporative cooling. Its role in saliva may be to enhance the wetting, softening and maceration of the dry, fibrous food for which equines are adapted. Latherin is unusual in its relatively high content of aliphatic amino acids (~25% leucines) that might contribute to its surfactant properties. Latherin is related to the palate, lung, and nasal epithelium carcinoma-associated protein...
Holland M, Kelly AB, Snyder JR, Steffey EP, Willits N, McNeal D.A chromogenic peptide substrate assay was used to determine serially plasma antithrombin III (AT III) activity in 4 groups of horses. Group I consisted of healthy, mature horses in which AT III activity was determined twice daily for 7 consecutive days. Groups 2 and 3 contained healthy horses in which AT III activity was monitored for 7 days after controlled, but varying, conditions of general anesthesia and surgery (median celiotomy). Group 4 was made up of patients with a presurgical diagnosis of colonic torsion. In healthy awake horses (group I), there was no difference in AT III values ove...
Morozova L, Haezebrouck P, Van Cauwelaert F.The thermal denaturation of Ca(2+)- and apo-forms of equine lysozyme was followed by using far and near UV circular dichroism and intrinsic fluorescence methods. The difference found between the temperature dependence of the ellipticity at 222 nm and 287 nm, which show two stages in the thermal transition, and those at 228 nm and 294 nm, which indicate only one stage over a wide range of temperatures reflects that different subdivisions of the protein molecule are characterized by a different stability, cooperativity and pathway of denaturation. The first transition, reflected in the increase ...
Balao da Silva C, Macías-García B, Morillo Rodriguez A, Gallardo Bolaños JM, Tapia JA, Aparicio IM, Morrell JM, Rodriguez-Martínez H....The only known means of effectively separating populations of X and Y bearing sperms is the Beltsville sexing technology. The technology implies that each individual sperm is interrogated for DNA content, measuring the intensity of the fluorescence after staining the spermatozoa with Hoechst 33342. Because there are no data regarding the effect of the staining on stallion sperm, ejaculates were incubated up to 90 min in presence of 0, 4.5, 9, 22.5, 31.5, 45, 54, 67.5, 76.5 and 90 μM of Hoechst 33342, in two media, KMT or INRA-Tyrodes. After 40 and 90 min of incubation, motility (CASA) and mem...
Bader H.A total of 23 mares were inseminated once within 0-6 h after clinical detection of ovulation, 14 with fresh and 9 with deep-frozen semen containing 0.1 x 10(9) to 4.7 x 10(9) motile spermatozoa. Within these two groups, the mares were slaughtered 2, 4 or 6 h after insemination and their genital tracts removed. The utero-tubal junction, isthmus and ampulla ipsilateral to the ovary in which ovulation occurred were flushed separately for sperm recovery. In 1 or 2 mares of each group, the uterine horn and corpus uteri, the cervix and vagina were also flushed. Tissue samples were collected from the...
Donahue SW.August Krogh was a comparative physiologist who used frogs, guinea pigs, cats, dogs, and horses in his research that led to his Nobel Prize on muscle physiology. His idea to choose the most relevant organism to study problems in physiology has become known as Krogh's principle. Indeed, many important discoveries in physiology have been made using naturally occurring animal models. However, the majority of research today utilizes laboratory mouse and rat models to study problems in physiology. This paper discusses how Krogh's principle can be invoked in musculoskeletal research as a complementa...
Penrod LV, Allen RE, Turner JL, Limesand SW, Arns MJ.Increased secretion of prostaglandin F(2)α (PGF(2)α) within the uterus because of uterine inflammation can cause luteolysis and result in early embryonic loss. Supplementation with polyunsaturated fatty acids (PUFAs) has been shown to influence PG production in many species, although the effects on the mare remain unknown. The present study aimed to determine fatty acid uptake in equine endometrial explants and evaluate their influence on PG secretion and expression of enzymes involved in PG synthesis in vitro. Equine endometrial explants were treated with 100 μM arachidonic acid, eicosapen...
Werpy NM, Ho CP, Garcia EB, Kawcak CE.Eight skeletally mature equine cadaver distal forelimbs were imaged using T2-weighted fast spin echo (FSE) sequences in a 1.0 T horizontal bore magnet. Each limb was parallel to the main magnetic field and with 16° angulation of the limb relative to the main magnetic field, which places one of the collateral ligaments of the distal interphalangeal joint at or near the magic angle. Each limb was imaged using an echo time (TE) of 80, 100, 120, and 140 ms. Reversal of the magic angle effect was achieved at echo time of 140 ms. However, given the alterations in tissue contrast and subjective decr...
Ruckebusch Y, Roger T.The electromyogram of the terminal ileum, the caecum and the proximal right ventral colon was recorded in fasted conscious ponies receiving intravenously equiactive doses of pilocarpine (0.05 mg/kg) and carbachol (0.01 mg/kg) as acetylcholine analogues; cisapride (0.1 mg/kg) and metoclopramide (2 mg/kg) facilitating acetylcholine release from myenteric neurones and naloxone (0.05 mg/kg) as an antagonist of the endogenous inhibitory opioid system. Both cisapride and naloxone induced typical migrating spike bursts in the colon associated with contractions of caecal body and caecal base. Both pil...
Smith CL, MacDonald MH, Tesch AM, Willits NH.To evaluate the effects of dimethyl sulfoxide (DMSO) on equine articular cartilage matrix metabolism. Methods: Using a cartilage explant culture system, proteoglycan (PG) synthesis, PG release, lactate metabolism, chondrocyte viability, and metabolism recovery were determined after cartilage exposure to DMSO. Methods: Cartilage harvested from metacarpophalangeal and metatarsophalangeal joints of 12 horses (age range, 1 to 10 years). Methods: Explants were exposed to concentrations of DMSO (1% to 20%) for variable times (3 to 72 hours). PG synthesis and release were determined by a radiolabel i...
Vendrig JC, Coffeng LE, Fink-Gremmels J.Increasing evidence suggests that reactions to lipopolysaccharide (LPS), particularly in the gut, can be partly or completely mitigated by colostrum- and milk-derived oligosaccharides. Confirmation of this hypothesis could lead to the development of new therapeutic concepts. Objective: To demonstrate the influence of equine colostral carbohydrates on the inflammatory response in an in vitro model with equine peripheral blood mononuclear cells (PBMCs). Methods: Carbohydrates were extracted from mare colostrum, and then evaluated for their influence on LPS-induced inflammatory responses in PBMCs...
Adams R, Mayhew IG.Behaviour and response to neurological testing of apparently healthy newborn foals differed significantly from the adult in several ways. Foals responded to external stimulation with exaggerated movements although they tended to sink into a relaxed state when restrained. They had a more angular head position and assumed a base wide stance. The menace reflex developed during the first two weeks post partum. In general, the foals' gait was choppy or dysmetric. In lateral recumbency the foals had increased extensor tone, hyperreflexive tendon reflexes, crossed extensor reflexes as well as recumbe...
Hosaka Y, Sakamoto Y, Kirisawa R, Watanabe T, Ueda H, Takehana K, Yamaguchi M.Although tumor necrosis factor (TNF) alpha is an important key factor in degeneration of equine superficial digital flexor tendon (SDFT), the dynamism of TNF receptors and associated factors on tendinocytes has not been elucidated. To reveal signaling events mediated by TNF-receptors (TNF-Rs) in tendinocytes, we focused on four signaling factors, TNF-R1, TNF-R2, TNF-R-associated factor 2 (TRAF2) and nuclear factor-kappa B (NF-kappaB), and investigated the distribution and production of these factors. Cultured tendinocytes were obtained from SDFTs of thoroughbred horses. The tendinocytes were t...
Faramarzi B, Thomason JJ, Sears WC.To quantitate changes in hoof wall growth and hoof morphology induced by mild exercise in Standardbreds. Methods: 18 Standardbreds. Methods: Horses were exercised at approximately 6 m/s (4,200 to 5,600 m/d) on 4 d/wk for 17 weeks. Both exercise (n = 9) and nonexercise (control group; 9) groups were housed in a large paddock throughout the study. At the beginning and end of the study, right forelimb feet of all horses were digitally photographed and underwent magnetic resonance imaging. Hoof wall measurements were obtained from the images to evaluate hoof wall growth and morphometric variables....
Liburt NR, McKeever KH, Malinowski K, Smarsh DN, Geor RJ.This study tested the hypotheses that age-induced alteration in cortisol, ACTH, and glucose concentrations are due to differences in the response of the hypothalamic-pituitary-adrenal axis and that exercise training would attenuate these differences. Six old (22.0±0.7 yr; mean±SE) and 6 young (7.3±0.6 yr) unfit Standardbred mares ran 3 graded exercise tests (GXT): before (GXT1), after 8 wk of training (GXT2), and at study end at 15 wk (GXT3). Mares trained 3 d/wk at 60% maximum heart rate. Each mare underwent 5 endocrine stimulation tests pre- and posttraining: 1) control (CON), 2) adrenoco...
McCann ME, Moore JN, Carrick JB, Barton MH.The effect of intravenous administration of lipid emulsions enriched with omega-3 (n3) and omega-6 (n6) fatty acids on equine monocyte phospholipid fatty acid composition and the synthesis of inflammatory mediators in vitro was evaluated. In a randomized crossover design, horses were infused intravenously with 20% lipid emulsions containing n3 or n6 fatty acids. Monocytes were isolated from the horses before and 0 h, 8 h, 24 h, and 7 days after lipid infusion. Monocyte fatty acid analysis demonstrated incorporation of the parenteral n3 and n6 fatty acids in monocyte phospholipids immediately a...
Hurd H.A total of 28 components were detected in the free amino acid (FAA) pool of hydatid fluid from primary and secondary equine cysts, secondary ovine cysts and host plasma. Examination of data from equine cysts revealed that the majority of FAAs were present in significantly greater concentrations in secondary cysts, glycine being over 30 times more concentrated. Values for total carbohydrates and glucose did not, however, differ significantly and total protein content was greater in primary cysts. Comparison of the (FAA) pool of secondary equine and ovine cysts revealed strain variation. It was ...
Provost PJ, Stick JA, Patterson JS, Hauptman JG, Robinson NE, Roth R.Large colon torsion frequently is a fatal condition in horses. The purpose of the study reported here was to determine systemic arterial pressure, plasma eicosanoid concentrations, colonic blood flow, vascular resistance, tissue pH, and morphologic features associated with large colon torsion and detorsion, and to evaluate the effects of sodium heparin (80 IU/kg of body weight, IV) treatment on these values. Values were determined in 20 anesthetized ponies that were randomly assigned into 4 equal groups: control; control/heparin; torsion; torsion/heparin. Torsions were created by a 720 degrees...
Hagen KB, Tschudin A, Liesegang A, Hatt JM, Clauss M.It is generally assumed that animal species differ in physiological characteristics of their digestive tract. Because investigating digestive processes is often labour-intensive, requiring lengthy adaptation and collection periods, comparisons are often made on the basis of data collated from different studies. We added a new data set on dietary crude fibre (CF) and macromineral (Na, K, Ca, P, Mg) composition and apparent digestibility (aD) of organic matter (OM) and macrominerals in rabbits (Oryctolagus cuniculus; a total of 180 measurements with 12 individuals and 10 different diets) to a li...
Mienaltowski MJ, Huang L, Bathke AC, Stromberg AJ, MacLeod JN.Human and equine cell transplant strategies for cartilage lesions usually result in scar tissue that is similar to what is produced naturally during the repair process. In this study, culture-expanded de-differentiated chondrocytes and primary bone marrow stromal cells at a pre-transplantation time-point were compared along with neonatal cartilage to repair tissue. Transcriptional profiling using a 9413-probeset equine-specific cDNA microarray and targeted real-time quantitative polymerase chain reaction validation were used to characterize relationships between these cell types and repair tis...
Marti M, Mevissen M, Althaus H, Steiner A.The goal of this study was to investigate the effect of bethanechol (BeCh) on contractility patterns of smooth muscle preparations of equine duodenum descendens, jejunum, caecum and pelvic flexure in vitro. Concentration-response relationships were developed for BeCh using in vitro assays with and without preincubation of muscarinic (M) receptor antagonists for M2 and M3 receptors. BeCh induced a significant, concentration-dependent increase in contractile response in equine intestine in specimens with circular orientation. The maximal effect was largest for jejunal specimens with no differenc...
Barello C, Garoffo LP, Montorfano G, Zava S, Berra B, Conti A, Giuffrida MG.Although several studies have aimed to identify mare's milk proteins, only the major whey proteins and some caseins have yet been characterized. Incomplete sequencing of the equine genome and the difficulty of recovering highly hydrophobic proteins mean that little is known to date about the proteins associated with milk fat globules, which have been shown to play an important role in newborns' defense mechanisms. The fat fraction, in particular the distribution of unsaturated fatty acids, has been more extensively studied, but complex lipids are only partially elucidated. This study reports a...
Saint-Dizier M, Chopineau M, Dupont J, Daels PF, Combarnous Y.Luteal steroids are necessary to maintain the first 70-90 days of pregnancy in the mare. At 35 days postovulation, the resurgence of the primary corpus luteum (CL) coincides with the secretion of the fetal hormone eCG. In order to study the responsiveness of the primary CL to eCG, we have examined levels of luteal equine LH/CG receptors (eLH/CG-R) mRNAs by Northern blot analysis and measured concentrations of eLH/CG binding sites on luteal membranes using 125I-eLH saturation binding assays at three stages of gestation: before the onset of eCG secretion (Days 14-31), from onset to maximum eCG s...
