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Author Williams, D.O.; Boatwright, R.B.; Rugh, K.S.; Garner, H.E.; Griggs, D.M.J.
Title Myocardial blood flow, metabolism, and function with repeated brief coronary occlusions in conscious ponies Type Journal Article
Year 1991 Publication The American journal of physiology Abbreviated Journal Am J Physiol
Volume 260 Issue 1 Pt 2 Pages H100-9
Keywords Animals; Consciousness/*physiology; Coronary Circulation/*physiology; Coronary Disease/pathology/*physiopathology; Disease Models, Animal; Hemodynamic Processes/physiology; Horses/*physiology; Hydrogen/metabolism; Lactates/metabolism; Myocardium/*metabolism/pathology; Norepinephrine/metabolism; Potassium/metabolism; Regional Blood Flow
Abstract Studies were performed in the conscious pony instrumented with a Doppler flow probe and hydraulic occluder on the left anterior descending coronary artery (LAD), sonomicrometry crystals and intraventricular micromanometer in the left ventricle, and catheters in the left atrium and anterior interventricular vein. Two-minute LAD occlusions were performed every 30 min continuously or during working hours. Data on release of catabolites (potassium, hydrogen ions, and lactate) and norepinephrine from the initially dysfunctional region were obtained periodically during a regimen of 445 +/- 56 occlusions in six animals. Regional myocardial blood flow was measured (microsphere method) before and after an occlusion regimen in four animals. Marked release of catabolites and norepinephrine from the initially dysfunctional region was noted in association with early occlusions when myocardial segment function was severely reduced. With further occlusions, release of these substances decreased while segment function improved. Blood flow was markedly decreased in the initially dysfunctional region during an early occlusion but was at the control level during a later occlusion. Although the metabolic findings are consistent with protection due to “ischemic preconditioning” and no increase in collateral perfusion, the inverse relationship noted between catabolite release and segment function is best explained by flow-dependent mechanisms. These results, together with the myocardial blood flow data, serve to validate a previous assumption that protection against regional myocardial dysfunction under these conditions is due to increased collateral perfusion.
Address Department of Physiology, University of Missouri, Columbia 65212
Corporate Author Thesis
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Language English Summary Language Original Title
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ISSN (up) 0002-9513 ISBN Medium
Area Expedition Conference
Notes PMID:1992786 Approved no
Call Number refbase @ user @ Serial 98
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Author McHugh, C.P.
Title Ecology of a semi-isolated population of adult Anopheles freeborni: abundance, trophic status, parity, survivorship, gonotrophic cycle length, and host selection Type Journal Article
Year 1989 Publication The American Journal of Tropical Medicine and Hygiene Abbreviated Journal Am J Trop Med Hyg
Volume 41 Issue 2 Pages 169-176
Keywords Aging/physiology; Animals; Anopheles/*physiology; Breeding; California; Cattle/parasitology; Dogs/parasitology; Ecology; Feeding Behavior/physiology; Female; Horses/parasitology; Host-Parasite Relations; Male; Parity; Population Density; Rabbits/parasitology
Abstract A population of adult Anopheles freeborni near Sheridan, CA was sampled daily during 13 August-7 September 1984. Data on abundance, trophic status, and gonotrophic age were recorded. Abundance and gonotrophic age data were analyzed to estimate daily survivorship and gonotrophic cycle length. Daily survivorship for unfed mosquitoes was estimated to be 0.72 with a gonotrophic cycle of 6 days duration. Daily survivorship for bloodfed mosquitoes was estimated to be 0.74 with a gonotrophic cycle of 4 days. The 2 day difference in gonotrophic cycles between unfed and bloodfed mosquitoes was the result of the period required for maturation and mating of teneral females. In 1986, an incage release of field-collected females estimated survivorship at 0.75 per day. Precipitin tests of 1,338 blood-engorged mosquito abdomens indicated that bovids, horses, rabbits, and canids comprised 92% of bloodmeals; no bloodmeals of human origin were detected.
Address Department of Entomology, University of California, Davis
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN (up) 0002-9637 ISBN Medium
Area Expedition Conference
Notes PMID:2774063 Approved no
Call Number Equine Behaviour @ team @ Serial 2673
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Author Hardy, J.L.
Title The ecology of western equine encephalomyelitis virus in the Central Valley of California, 1945-1985 Type Journal Article
Year 1987 Publication The American Journal of Tropical Medicine and Hygiene Abbreviated Journal Am J Trop Med Hyg
Volume 37 Issue 3 Suppl Pages 18s-32s
Keywords Aedes/microbiology; Animals; Birds; California; Culex/microbiology; Encephalitis Virus, Western Equine/*physiology; Encephalomyelitis, Equine/*history/microbiology/transmission/veterinary; History, 20th Century; Horse Diseases/history/transmission; Horses; Humans; Insect Vectors/microbiology; Mammals
Abstract Reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. Extensive field and laboratory studies done since 1945 in the Central Valley of California have more clearly defined the specific invertebrate and vertebrate hosts involved in the basic virus transmission cycle, but the overall concept remains unchanged. The basic transmission cycle involves Culex tarsalis as the primary vector mosquito species and house finches and house sparrows as the primary amplifying hosts. Secondary amplifying hosts, upon which Cx. tarsalis frequently feeds, include other passerine species, chickens, and possibly pheasants in areas where they are abundant. Another transmission cycle that most likely is initiated from the Cx. tarsalis-wild bird cycle involves Aedes melanimon and the blacktail jackrabbit. Like humans and horses, California ground squirrels, western tree squirrels, and a few other wild mammal species become infected tangentially with the virus but do not contribute significantly to virus amplification.
Address Department of Biomedical and Environmental Health Sciences, School of Public Health, University of California, Berkeley 94720
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN (up) 0002-9637 ISBN Medium
Area Expedition Conference
Notes PMID:3318522 Approved no
Call Number Equine Behaviour @ team @ Serial 2677
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Author Spadavecchia, C.; Arendt-Nielsen, L.; Andersen, O.K.; Spadavecchia, L.; Doherr, M.; Schatzmann, U.
Title Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses Type Journal Article
Year 2003 Publication American journal of veterinary research Abbreviated Journal Am J Vet Res
Volume 64 Issue 6 Pages 700-707
Keywords Animals; Consciousness; Female; Forelimb/*physiology; Hindlimb/*physiology; Horses/*physiology; Male; Nociceptors/physiology; Pain/*physiopathology/*veterinary; Pain Threshold/physiology; Recruitment, Neurophysiological/physiology; Reflex/*physiology
Abstract OBJECTIVE: To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. ANIMALS: 20 adult horses. PROCEDURE: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold intensity was reached. The EMG signal was analyzed for quantification of the NWR. Behavioral responses accompanying the reflex were scored (scale, 0 to 5). The NWR recruitment curves were determined at 0.9, 1.1, 1.2, and 1.3 times the NWR threshold intensity. RESULTS: The NWR threshold was significantly higher for the hind limb (median value, 6.6 mA; range, 3 to 10 mA) than the forelimb (median, 3 mA; range, 1.7 to 5.5 mA). The NWR of the hind limb had a significantly longer latency (median, 122.8 milliseconds; range, 106 to 172 milliseconds), compared with the forelimb (median, 98 milliseconds; range, 86 to 137 milliseconds), and it was associated with significantly stronger behavioral reactions. Gradual increase of NWR amplitude was evident at increasing stimulation intensities and supported by the behavioral observations. CONCLUSIONS AND CLINICAL RELEVANCE: We documented NWRs evoked from the forelimb and hind limb and their recruitment with stimuli of increasing intensity in horses. These results provide a basis for use of NWRs in studies on nociceptive modulation in horses.
Address Department of Clinical Veterinary Sciences, University of Berne, Switzerland
Corporate Author Thesis
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Language English Summary Language Original Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:12828255 Approved no
Call Number refbase @ user @ Serial 93
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Author Keiper, R.; Houpt, K.
Title Reproduction in feral horses: an eight-year study Type Journal Article
Year 1984 Publication American journal of veterinary research Abbreviated Journal Am J Vet Res
Volume 45 Issue 5 Pages 991-995
Keywords Abortion, Veterinary/epidemiology; Anestrus; Animal Population Groups/*physiology; Animals; Animals, Wild/*physiology; Birth Rate; Female; Fertility; Horse Diseases/epidemiology; Horses/*physiology; Lactation; Male; Maryland; Pregnancy; *Reproduction; Seasons; Sex Ratio; Virginia
Abstract The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.
Address
Corporate Author Thesis
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:6732036 Approved no
Call Number refbase @ user @ Serial 665
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Author Kurvers, C.M.H.C.; van Weeren, P.R.; Rogers, C.W.; van Dierendonck, M.C.
Title Quantification of spontaneous locomotion activity in foals kept in pastures under various management conditions Type Journal Article
Year 2006 Publication American journal of veterinary research Abbreviated Journal Am J Vet Res
Volume 67 Issue 7 Pages 1212-1217
Keywords Aging; Animal Husbandry; Animals; Female; Horses/*physiology; Male; Motor Activity/*physiology; Sex Characteristics
Abstract OBJECTIVE: To describe spontaneous locomotion activity of foals kept under various management conditions and assess the suitability of global positioning system (GPS) technology for recording foal activity. Animals-59 foals. PROCEDURES: During the foals' first 4 months of life, 921 observation periods (15 minutes each) were collected and analyzed for locomotion activities. The GPS system was evaluated by simultaneously carrying out field observations with a handheld computer. RESULTS: Foals spent 0.5% of total observed time cantering, 0.2% trotting, 10.7% walking, 32.0% grazing, 34.8% standing, and 21.6% lying down. Total observed daytime workload (velocity x distance) in the first month was approximately twice that in the following months. Locomotion activity decreased with increasing age. Colts had more activity than fillies in certain periods, and foals that were stabled for some portion of the day had compensatory locomotion activity, which was probably insufficient to reach the level of foals kept continually outside. The GPS recordings and handheld-computer observations were strongly correlated for canter, trot, and walk and moderately correlated for standing and lying. Correlation for grazing was low. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that domestically managed foals, when kept 24 h/d at pasture, will exercise at a level comparable with feral foals. High workload during the first month of life might be important for conditioning the musculoskeletal system. The GPS technique accurately quantified canter, trot, and walk activities; less accurately indexed resting; and was unsuitable for grazing because of the wide array of velocities used while foraging.
Address Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
Corporate Author Thesis
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Language English Summary Language Original Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:16817745 Approved no
Call Number Serial 1786
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Author McDonnell, S.M.; Freeman, D.A.; Cymbaluk, N.F.; Schott, H.C. 2nd; Hinchcliff, K.; Kyle, B.
Title Behavior of stabled horses provided continuous or intermittent access to drinking water Type Journal Article
Year 1999 Publication American Journal of Veterinary Research Abbreviated Journal Am J Vet Res
Volume 60 Issue 11 Pages 1451-1456
Keywords Aggression; Animal Husbandry; Animals; Behavior, Animal/*physiology; Drinking Behavior; Feeding Behavior; Female; Horses/*physiology/*psychology; Housing, Animal; Pregnancy; Pregnancy, Animal/physiology/*psychology; Social Behavior; Videotape Recording; *Water Supply
Abstract OBJECTIVE: To compare quantitative measures and clinical assessments of behavior as an indication of psychologic well-being of stabled horses provided drinking water continuously or via 1 of 3 intermittent delivery systems. ANIMALS: 22 Quarter Horse (QH) or QH-crossbred mares and 17 Belgian or Belgian-crossbred mares (study 1) and 24 QH or QH-crossbred mares and 18 Belgian or Belgian-crossbred mares (study 2). PROCEDURE: Stabled horses were provided water continuously or via 1 of 3 intermittent water delivery systems in 2 study periods during a 2-year period. Continuous 24-hour videotaped samples were used to compare quantitative measures and clinical assessments of behavior among groups provided water by the various water delivery systems. RESULTS: All horses had clinically normal behavior. Significant differences in well being were not detected among groups provided water by the various delivery systems. CONCLUSIONS AND CLINICAL RELEVANCE: Various continuous and intermittent water delivery systems can provide adequately for the psychologic well-being of stabled horses.
Address New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square 19348, USA
Corporate Author Thesis
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:10566826 Approved no
Call Number refbase @ user @ Serial 1928
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Author Clayton, H.M.
Title Comparison of the stride kinematics of the collected, medium, and extended walks in horses Type Journal Article
Year 1995 Publication American Journal of Veterinary Research Abbreviated Journal Am J Vet Res
Volume 56 Issue 7 Pages 849-852
Keywords Analysis of Variance; Animals; *Gait; Horses/*physiology; *Locomotion; Motion Pictures; Physical Conditioning, Animal; Walking
Abstract Six horses, highly trained for dressage competition, were used to study the stride kinematics of the walk, and to compare the kinematics of the collected, medium, and extended walks. Horses were filmed in a sagittal plane at a rate of 150 frames/s; temporal, linear, and angular data were extracted from the films. Results of ANOVA and Duncan's multiple range test indicated that the speed of the collected walk (1.37 m/s) was significantly (P < 0.01) slower than that of the medium (1.73 m/s) and extended (1.82 m/s) walks, values for which were not significantly different from each other. The increase in speed was associated with a significant increase in stride length, from 157 cm in the collected walk to 193 cm in the extended walk. This was a result of an increase in the over-tracking distance, whereas there was no significant difference in the distance between lateral placements of the limbs. Stride duration decreased (P < 0.01) from the collected walk (1,159 ms) to the extended walk (1,064 ms). Angles of the metacarpal and metatarsal segments, measured on the palmar/ plantar aspect, were higher at impact and lower at lift off in the collected than in the extended walk (P < 0.01). This indicated greater range of angular motion of this segment during the stance phase in the extended walk. Only 1 of the 6 horses had a regular 4-beat rhythm of the footfalls, with equal time elapsing between the lateral and diagonal footfalls.
Address Department of Veterinary Anatomy, Western College of Veterinary Medicine, Canada
Corporate Author Thesis
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Language English Summary Language Original Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:7574149 Approved no
Call Number Equine Behaviour @ team @ Serial 3743
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Author Santamaria, S.; Bobbert, M.E.; Back, W.; Barneveld, A.; van Weeren, P.R.
Title Variation in free jumping technique within and among horses with little experience in show jumping Type Journal Article
Year 2004 Publication American Journal of Veterinary Research Abbreviated Journal Am J Vet Res
Volume 65 Issue 7 Pages 938-944
Keywords *Acceleration; Analysis of Variance; Animals; Biomechanics; Forelimb/physiology; Gait/*physiology; Hindlimb/physiology; Horses/*physiology; Locomotion/*physiology; Models, Biological; Video Recording
Abstract OBJECTIVE: To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses. ANIMALS: Fifteen 4-year-old Dutch Warmblood horses. PROCEDURE: The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m. RESULTS: Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff (r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb push-off. However, all horses cleared the fence successfully, independent of jumping technique. CONCLUSIONS AND CLINICAL RELEVANCE: Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses.
Address Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, NL-3584 CM Utrecht, The Netherlands
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Language English Summary Language Original Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:15281652 Approved no
Call Number Equine Behaviour @ team @ Serial 3772
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Author Santamaria, S.; Bobbert, M.F.; Back, W.; Barneveld, A.; van Weeren, P.R.
Title Effect of early training on the jumping technique of horses Type Journal Article
Year 2005 Publication American Journal of Veterinary Research Abbreviated Journal Am J Vet Res
Volume 66 Issue 3 Pages 418-424
Keywords Age Factors; Analysis of Variance; Animals; Biomechanics; Forelimb/physiology; Gait/*physiology; Hindlimb/physiology; Horses/growth & development/*physiology; Locomotion/*physiology; Models, Biological; Physical Conditioning, Animal/*methods
Abstract OBJECTIVE: To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally. ANIMALS: 40 Dutch Warmblood horses. PROCEDURE: The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance. RESULTS: Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition. CONCLUSIONS AND CLINICAL RELEVANCE: Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent.
Address Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, NL-3584 CM Utrecht, The Netherlands
Corporate Author Thesis
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN (up) 0002-9645 ISBN Medium
Area Expedition Conference
Notes PMID:15822585 Approved no
Call Number Equine Behaviour @ team @ Serial 4037
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