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Author Houpt, K.A.; Thornton, S.N.; Allen, W.R.
Title Vasopressin in dehydrated and rehydrated ponies Type Journal Article
Year 1989 Publication Physiology & behavior Abbreviated Journal Physiol. Behav.
Volume 45 Issue 3 Pages 659-661
Keywords Animals; Behavior, Animal/*physiology; Dehydration/*blood; Drinking Behavior/*physiology; Female; Horses/*blood; Osmolar Concentration; Reaction Time; Time Factors; Vasopressins/*blood
Abstract Six pony mares deprived of water for 24 hours showed significant increases in plasma vasopressin (2.8 pg/ml) and osmolality (9 mosmol/kg). When water was made available the ponies drank rapidly (5 of 6 drank to satiety within 90 seconds) and corrected their fluid deficits precisely. Vasopressin did not return to predehydration levels until osmolality did after 15 minutes of access to water. The horse differs from rodents and humans, but is similar to pigs in that vasopressin levels do not fall before osmolality returns to normal. Oropharyngeal factors, therefore, may not be as important in vasopressin release in horses as in other species.
Address New York State College of Veterinary Medicine, Cornell University, Ithaca 14853-6401
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 0031-9384 ISBN Medium
Area Expedition Conference
Notes PMID:2756059 Approved no
Call Number refbase @ user @ Serial (down) 45
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Author Houpt, K.A.; Eggleston, A.; Kunkle, K.; Houpt, T.R.
Title Effect of water restriction on equine behaviour and physiology Type Journal Article
Year 2000 Publication Equine veterinary journal Abbreviated Journal Equine Vet J
Volume 32 Issue 4 Pages 341-344
Keywords Animals; *Behavior, Animal; Blood Proteins/analysis; Energy Intake; Female; Horse Diseases/physiopathology; Horses/*physiology; Osmolar Concentration; Pregnancy; Stress/veterinary; Video Recording; Water Deprivation/*physiology
Abstract Six pregnant mares were used to determine what level of water restriction causes physiological and/or behavioural changes indicative of stress. Nonlegume hay was fed ad libitum. During the first week of restriction, 5 l water/100 kg bwt was available, during the second week 4 l/100 kg bwt and, during the third week, 3 l/100 kg bwt. Ad libitum water intake was 6.9 l/100 kg bwt; at 3 l/100 kg bwt water intake was 42% of this. Daily hay intake fell significantly with increasing water restriction from 12.9 +/- 0.75 kg to 8.3 +/- 0.54 kg; bodyweight fell significantly for a total loss of 48.5 +/- 8.3 kg in 3 weeks. Daily blood samples were analysed; osmolality rose significantly with increasing water restriction from 282 +/- 0.7 mosmols/kg to 293.3 +/- 0.8 mosmols/kg bwt, but plasma protein and PCV did not change significantly. Cortisol concentrations fell from 8.1 ng/ml to 6.4 ng/ml over the 3 week period. Aldosterone fell from 211.3 +/- 74.2 pg/ml to 92.5 +/- 27.5 pg/ml at the end of the first week. The behaviour of 4 of the 6 mares was recorded 24 h/day for the duration of the study. The only significant difference was in time spent eating, which decreased with increasing water restriction from 46 +/- 3% to 30 +/- 3%. It is concluded that water restriction to 4 l/100 kg bwt dehydrates pregnant mares and may diminish their welfare, but is not life- or pregnancy-threatening.
Address Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, 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
Area Expedition Conference
Notes PMID:10952384 Approved no
Call Number refbase @ user @ Serial (down) 32
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