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Author Sivak, J.G.; Allen, D.B.
Title An evaluation of the “ramp” retina of the horse eye Type Journal Article
Year 1975 Publication Vision Research Abbreviated Journal Vision Res
Volume 15 Issue 12 Pages 1353-1356
Keywords Accommodation, Ocular; Animals; Aqueous Humor/physiology; Cornea/physiology; Freezing; Horses/*anatomy & histology; Lens, Crystalline/anatomy & histology/physiology; Refraction, Ocular; Retina/*anatomy & histology; Vitreous Body/physiology
Abstract Using a rapid freezing and sectioning technique, the distance between the lens and retina of the horse eye was measured. There is no indication of a ramp retina that could serve accommodation. The pupil axis of the eye coincides with the maximum lens to retina distance. The changes in the lens-retina distance are greater below the axis than above it. Calculations were made of refractive power of the horse eye from measurements of curvature and refractive indices of the ocular tissues. These calculations agree both qualitatively and quantitatively with retinoscopic measurements on live horses. Both show that the refractive state shifts in the direction of hyperopia above and below the axis and that this shift is greater below the axis than above it. Some dynamic accommodative ability in the living eye was observed.
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Language English Summary Language Original Title
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ISSN 0042-6989 ISBN Medium (down)
Area Expedition Conference
Notes PMID:1210017 Approved no
Call Number Equine Behaviour @ team @ Serial 3647
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Author Rhodin, M.; Johnston, C.; Holm, K.R.; Wennerstrand, J.; Drevemo, S.
Title The influence of head and neck position on kinematics of the back in riding horses at the walk and trot Type Journal Article
Year 2005 Publication Equine Veterinary Journal Abbreviated Journal Equine Vet J
Volume 37 Issue 1 Pages 7-11
Keywords Acceleration; Animals; Back/*physiology; Biomechanics; Exercise Test/veterinary; Female; Gait/*physiology; Head/*physiology; Horses/*physiology; Male; Movement/physiology; Neck/*physiology; Walking/physiology
Abstract REASONS FOR PERFORMING STUDY: A common opinion among riders and in the literature is that the positioning of the head and neck influences the back of the horse, but this has not yet been measured objectively. OBJECTIVES: To evaluate the effect of head and neck position on the kinematics of the back in riding horses. METHODS: Eight Warmblood riding horses in regular work were studied on a treadmill at walk and trot with the head and neck in 3 different predetermined positions achieved by side reins attached to the bit and to an anticast roller. The 3-dimensional movement of the thoracolumbar spine was measured from the position of skin-fixed markers recorded by infrared videocameras. RESULTS: Head and neck position influenced the movements of the back, especially at the walk. When the head was fixed in a high position at the walk, the flexion-extension movement and lateral bending of the lumbar back, as well as the axial rotation, were significantly reduced when compared to movements with the head free or in a low position. At walk, head and neck position also significantly influenced stride length, which was shortest with the head in a high position. At trot, the stride length was independent of head position. CONCLUSIONS: Restricting and restraining the position and movement of the head and neck alters the movement of the back and stride characteristics. With the head and neck in a high position stride length and flexion and extension of the caudal back were significantly reduced. POTENTIAL RELEVANCE: Use of side reins in training and rehabilitation programmes should be used with an understanding of the possible effects on the horse's back.
Address Department of Anatomy, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
Corporate Author Thesis
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0425-1644 ISBN Medium (down)
Area Expedition Conference
Notes PMID:15651727 Approved no
Call Number Equine Behaviour @ team @ Serial 3657
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Author Bailey, A.; Williams, N.; Palmer, M.; Geering, R.
Title The farmer as service provider: the demand for agricultural commodities and equine services Type Journal Article
Year 2000 Publication Agricultural Systems Abbreviated Journal
Volume 66 Issue 3 Pages 191-204
Keywords Income and price elasticity of demand; Farm diversification; Horses
Abstract In recent years there has been much interest in alternative sources of income for farmers. This is because economic theory suggests that demand for agricultural commodities is inelastic so that, as incomes in society as a whole increase, those of farmers do not necessarily keep pace — hence the current problems with falling real farm incomes. In contrast the demand for services is relatively elastic. Thus it is logical to divert agricultural resources into service provision. One such service is provided by equine enterprises. We have estimated the own price and income elasticities of demand for selected agricultural commodities and for ‘equine services’. Our results confirm that demand for equine services is more elastic than for agricultural commodities. Thus diversification into horse enterprises is likely to have long term benefits for farmers vis á vis traditional agricultural production.
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ISSN 0308-521x ISBN Medium (down)
Area Expedition Conference
Notes Approved no
Call Number Equine Behaviour @ team @ Serial 5713
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Author Boyd, L.; Bandi, N.
Title Reintroduction of takhi, Equus ferus przewalskii, to Hustai National Park, Mongolia: time budget and synchrony of activity pre- and post-release Type Journal Article
Year 2002 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.
Volume 78 Issue 2-4 Pages 87-102
Keywords Equids; Przewalski's horses; Takhi; Behaviour patterns; Time budgets; Behavioural synchrony; Reintroduction
Abstract A harem of takhi (Equus ferus przewalskii) was observed during introduction to the Hustain Nuruu Steppe Reserve of Mongolia. The goals were to examine whether the harem exhibited significant behavioural synchrony, whether release had an effect on time budget, and what the implications might be regarding acclimatisation to the wild. Behaviours were scan sampled every 10 min between the hours of 06:00 and 22:00, twice before release, twice immediately after release, and twice 2 years after reintroduction. Time budgets were constructed from these data. Considerable behavioural synchrony was evidenced both before and after release. Crepuscular grazing and midday resting were typical, regardless of the date relative to release. Upon release, the amount of time spent moving doubled for all age classes. It is suggested that this increase resulted from exploration. The amount of time spent grazing and standing remained unchanged; the increased amount of time spent moving came at the expense of resting. Two years later, the horses still spent more time moving than when captive. Somewhat less time was spent grazing, although the difference was not significant. More time was spent resting in 1996 than immediately after release. These time budgets provide evidence of successful acclimatisation to the wild. Trekking between favoured sites could account for the persistent increase in time spent moving, with concomitantly less time needed to meet nutritional needs by grazing and more time available for resting. Housing captive takhi in large enclosures is evidently insufficient to permit the amount of movement exhibited by this wild harem. The time budget of the 1- and 2-year olds was more similar to that of adults than foals, indicating approaching adulthood. That 1- and 2-year olds were nursed, without loss of body condition by the dam, provided additional evidence that the takhi achieved excellent nutritional status in the wild.
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Notes Approved no
Call Number Equine Behaviour @ team @ Serial 3690
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Author Anderson, T.M.; McIlwraith, C.W.; Douay, P.
Title The role of conformation in musculoskeletal problems in the racing Thoroughbred Type Journal Article
Year 2004 Publication Equine Veterinary Journal Abbreviated Journal Equine Vet J
Volume 36 Issue 7 Pages 571-575
Keywords Animals; Carpus, Animal/anatomy & histology/physiology; Horse Diseases/etiology/*pathology/surgery; Horses/*anatomy & histology/injuries/physiology; Likelihood Functions; Logistic Models; Muscle, Skeletal/*anatomy & histology/pathology; Musculoskeletal Diseases/pathology/surgery/*veterinary; Tarsus, Animal/anatomy & histology/physiology; Treatment Outcome
Abstract REASONS FOR PERFORMING STUDY: The relationship of conformation to future potential injury is a standard approach in practise but, at present, is largely based on subjective observations. OBJECTIVE: To measure conformation in 3-year-old Thoroughbreds and objectively test its relationship with the occurrence of musculoskeletal problems. METHODS: Conformation measurements were taken from photographs using specific reference points marked on the horses and processed on the computer. Clinical observations were recorded for each horse on a regular basis. Stepwise (forward) logistic regression analysis was performed to investigate the relationship between the binary response of the clinical outcomes probability and the conformation variables by the method of maximum likelihood. RESULTS: Clinical outcomes significantly (P<0.05) associated with conformational variables included effusion of the front fetlock, effusion of the right carpus, effusion of the carpus, effusion of the hind fetlock, fracture of the left or right carpus, right front fetlock problem and hind fetlock problem. CONCLUSIONS: Offset knees (offset ratio) contributed to fetlock problems. Long pasterns increased the odds of a fracture in the front limb. An increase in the carpal angle as viewed from the front (carpal valgus) may serve as a protective mechanism, as the odds for a carpal fracture and carpal effusion decreased with an increase in the carpal angle. POTENTIAL RELEVANCE: This study demonstrates relationships between conformation and musculoskeletal disease in the racehorse. The information may be useful in selection and management of the racing Thoroughbred.
Address Colorado State University, Equine Science and Equine Orthopaedic Research Programs, Fort Collins, Colorado 80523, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0425-1644 ISBN Medium (down)
Area Expedition Conference
Notes PMID:15581320 Approved no
Call Number Equine Behaviour @ team @ Serial 3697
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Author Gomez Alvarez, C.B.; Rhodin, M.; Bobber, M.F.; Meyer, H.; Weishaupt, M.A.; Johnston, C.; Van Weeren, P.R.
Title The effect of head and neck position on the thoracolumbar kinematics in the unridden horse Type Journal Article
Year 2006 Publication Equine Veterinary Journal. Supplement Abbreviated Journal Equine Vet J Suppl
Volume Issue 36 Pages 445-451
Keywords Animals; Biomechanics; Head/*physiology; Horses/*physiology; Lumbar Vertebrae/physiology; Male; Neck/*physiology; Physical Conditioning, Animal/physiology; Posture/*physiology; Sports; Thoracic Vertebrae/physiology; Weight-Bearing
Abstract REASONS FOR PERFORMING STUDY: In many equestrian activities a specific position of head and/or neck is required that is dissimilar to the natural position. There is controversy about the effects of these positions on locomotion pattern, but few quantitative data are available. OBJECTIVES: To quantify the effects of 5 different head and neck positions on thoracolumbar kinematics of the horse. METHODS: Kinematics of 7 high level dressage horses were measured walking and trotting on an instrumented treadmill with the head and neck in the following positions: HNP2 = neck raised, bridge of the nose in front of the vertical; HNP3 = as HNP2 with bridge of the nose behind the vertical; HNP4 = head and neck lowered, nose behind the vertical; HNP5 = head and neck in extreme high position; HNP6 = head and neck forward and downward. HNP1 was a speed-matched control (head and neck unrestrained). RESULTS: The head and neck positions affected only the flexion-extension motion. The positions in which the neck was extended (HNP2, 3, 5) increased extension in the anterior thoracic region, but increased flexion in the posterior thoracic and lumbar region. For HNP4 the pattern was the opposite. Positions 2, 3 and 5 reduced the flexion-extension range of motion (ROM) while HNP4 increased it. HNP5 was the only position that negatively affected intravertebral pattern symmetry and reduced hindlimb protraction. The stride length was significantly reduced at walk in positions 2, 3, 4 and 5. CONCLUSIONS: There is a significant influence of head/neck position on back kinematics. Elevated head and neck induce extension in the thoracic region and flexion in the lumbar region; besides reducing the sagittal range of motion. Lowered head and neck produces the opposite. A very high position of the head and neck seems to disturb normal kinematics. POTENTIAL RELEVANCE: This study provides quantitative data on the effect of head/neck positions on thoracolumbar motion and may help in discussions on the ethical acceptability of some training methods.
Address Department of Equine Sciences, Utrecht University, Yalelaan 12, 3584 CM Utrecht, The Netherlands
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Notes PMID:17402464 Approved no
Call Number Equine Behaviour @ team @ Serial 3702
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Author Weishaupt, M.A.; Wiestner, T.; von Peinen, K.; Waldern, N.; Roepstorff, L.; van Weeren, R.; Meyer, H.; Johnston, C.
Title Effect of head and neck position on vertical ground reaction forces and interlimb coordination in the dressage horse ridden at walk and trot on a treadmill Type Journal Article
Year 2006 Publication Equine Veterinary Journal. Supplement Abbreviated Journal Equine Vet J Suppl
Volume Issue 36 Pages 387-392
Keywords Animals; Biomechanics; Exercise Test/instrumentation/methods/*veterinary; Forelimb/physiology; Gait; Head/physiology; Hindlimb/physiology; Horses/*physiology; Locomotion/*physiology; Male; Neck/physiology; Physical Conditioning, Animal/methods/*physiology; Posture; Statistics, Nonparametric; Walking/*physiology
Abstract REASONS FOR PERFORMING STUDY: Little is known in quantitative terms about the influence of different head-neck positions (HNPs) on the loading pattern of the locomotor apparatus. Therefore it is difficult to predict whether a specific riding technique is beneficial for the horse or if it may increase the risk for injury. OBJECTIVE: To improve the understanding of forelimb-hindlimb balance and its underlying temporal changes in relation to different head and neck positions. METHODS: Vertical ground reaction force and time parameters of each limb were measured in 7 high level dressage horses while being ridden at walk and trot on an instrumented treadmill in 6 predetermined HNPs: HNP1 – free, unrestrained with loose reins; HNP2 – neck raised, bridge of the nose in front of the vertical; HNP3 – neck raised, bridge of the nose behind the vertical; HNP4 – neck lowered and flexed, bridge of the nose considerably behind the vertical; HNP5 – neck extremely elevated and bridge of the nose considerably in front of the vertical; HNP6 – neck and head extended forward and downward. Positions were judged by a qualified dressage judge. HNPs were assessed by comparing the data to a velocity-matched reference HNP (HNP2). Differences were tested using paired t test or Wilcoxon signed rank test (P<0.05). RESULTS: At the walk, stride duration and overreach distance increased in HNP1, but decreased in HNP3 and HNP5. Stride impulse was shifted to the forehand in HNP1 and HNP6, but shifted to the hindquarters in HNP5. At the trot, stride duration increased in HNP4 and HNP5. Overreach distance was shorter in HNP4. Stride impulse shifted to the hindquarters in HNP5. In HNP1 peak forces decreased in the forelimbs; in HNP5 peak forces increased in fore- and hindlimbs. CONCLUSIONS: HNP5 had the biggest impact on limb timing and load distribution and behaved inversely to HNP1 and HNP6. Shortening of forelimb stance duration in HNP5 increased peak forces although the percentage of stride impulse carried by the forelimbs decreased. POTENTIAL RELEVANCE: An extremely high HNP affects functionality much more than an extremely low neck.
Address Equine Hospital, University of Zurich, CH-8057 Zurich, Switzerland
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Notes PMID:17402453 Approved no
Call Number Equine Behaviour @ team @ Serial 3704
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Author Balakrishnan, G.; Hu, Y.; Spiro, T.G.
Title Temperature-jump apparatus with Raman detection based on a solid-state tunable (1.80-2.05 microm) kHz optical parametric oscillator laser Type Journal Article
Year 2006 Publication Applied Spectroscopy Abbreviated Journal Appl Spectrosc
Volume 60 Issue 4 Pages 347-351
Keywords Animals; Cytochromes c/analysis; Horses; Lasers; Myoglobin/metabolism; Spectrum Analysis, Raman/*instrumentation/*methods; *Temperature
Abstract The operating characteristics of a pulsed (10 ns) tunable near-infrared (NIR) laser source are described for temperature-jump (T-jump) applications. A Q-switched Nd:YLF laser (approximately 10 ns pulses) with a 1 kHz repetition rate is used to pump a potassium titanyl arsenate (KTA) crystal-based optical parametric oscillator (OPO), producing approximately 1 mJ NIR pulses that are tunable (1.80-2.05 microm) across the 1.9 microm vibrational overtone band of water. This T-jump source has been coupled to a deep ultraviolet (UV) probe laser for Raman studies of protein dynamics. T-jumps of up to 30 degrees C, as measured via the O-H stretching Raman band of water, are readily achieved. Application to cytochrome c unfolding is demonstrated.
Address Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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ISSN 0003-7028 ISBN Medium (down)
Area Expedition Conference
Notes PMID:16613628 Approved no
Call Number Equine Behaviour @ team @ Serial 3764
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Author Hagen, S.J.; Eaton, W.A.
Title Two-state expansion and collapse of a polypeptide Type Journal Article
Year 2000 Publication Journal of Molecular Biology Abbreviated Journal J Mol Biol
Volume 301 Issue 4 Pages 1019-1027
Keywords Animals; Computer Simulation; Cytochrome c Group/*chemistry/*metabolism; Horses; Kinetics; Lasers; Models, Chemical; Peptides/*chemistry/*metabolism; Protein Conformation; Protein Denaturation; *Protein Folding; Spectrometry, Fluorescence; Temperature; Thermodynamics
Abstract The initial phase of folding for many proteins is presumed to be the collapse of the polypeptide chain from expanded to compact, but still denatured, conformations. Theory and simulations suggest that this collapse may be a two-state transition, characterized by barrier-crossing kinetics, while the collapse of homopolymers is continuous and multi-phasic. We have used a laser temperature-jump with fluorescence spectroscopy to measure the complete time-course of the collapse of denatured cytochrome c with nanosecond time resolution. We find the process to be exponential in time and thermally activated, with an apparent activation energy approximately 9 k(B)T (after correction for solvent viscosity). These results indicate that polypeptide collapse is kinetically a two-state transition. Because of the observed free energy barrier, the time scale of polypeptide collapse is dramatically slower than is predicted by Langevin models for homopolymer collapse.
Address Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Building 5, Bethesda, MD, 20892-0520, USA
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ISSN 0022-2836 ISBN Medium (down)
Area Expedition Conference
Notes PMID:10966803 Approved no
Call Number Equine Behaviour @ team @ Serial 3790
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Author Kihara, H.; Nakatani, H.; Hiromi, K.; Hon-Nami, K.
Title Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide Type Journal Article
Year 1977 Publication Biochimica et Biophysica Acta Abbreviated Journal Biochim Biophys Acta
Volume 460 Issue 3 Pages 480-489
Keywords Animals; Bacteria; *Cytochrome c Group; *Ferrocyanides; Horses; Kinetics; Mathematics; Oxidation-Reduction; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; Thermodynamics
Abstract The oxidation-reduction reaction of horse heart cytochrome c and cytochrome c (552, Thermus thermophilus), which is highly thermoresistant, was studied by temperature-jump method. Ferrohexacyanide was used as reductant. (Formula: see text.) Thermodynamic and activation parameters of the reaction obtained for both cytochromes were compared with each other. The results of this showed that (1) the redox potential of cytochrome c-552, + 0.19 V, is markedly less than that of horse heart cytochrome c. (2) deltaHox of cytochrome c-552 is considerably lower than that of horse heart cytochrome c. (3) deltaSox and deltaSred of cytochrome c-552 are more negative than those of horse heart cytochrome c. (4) kred of cytochrome c-552 is much lower than that of horse heart cytochrome c at room temperature.
Address
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Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0006-3002 ISBN Medium (down)
Area Expedition Conference
Notes PMID:195599 Approved no
Call Number Equine Behaviour @ team @ Serial 3815
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