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Houpt, K. A. (2006). Why horse behaviour is important to the equine clinician. Equine Vet J, 38(5), 386–387.
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Houpt, K. A., Thornton, S. N., & Allen, W. R. (1989). Vasopressin in dehydrated and rehydrated ponies. Physiol. Behav., 45(3), 659–661.
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.
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Houpt, K. A., Northrup, N., Wheatley, T., & Houpt, T. R. (1991). Thirst and salt appetite in horses treated with furosemide. J Appl Physiol, 71(6), 2380–2386.
Abstract: When a preliminary experiment in sodium-replete ponies revealed an increase, but not a significant increase, in salt consumption after furosemide treatment, the experiment was repeated using sodium-deficient horses in which aldosterone levels might be expected to be elevated to test the hypothesis that a background of aldosterone is necessary for salt appetite. Ten Standardbred mares were injected intravenously with furosemide or an equivalent volume of 0.9% sodium chloride as a control to test the effect of furosemide on their salt appetite and blood constituents. Sodium intake and sodium loss in urine, as well as water intake and urine output, were measured and compared to determine accuracy of compensation for natriuresis and diuresis. Plasma protein and packed cell volume showed significant increases in response to furosemide treatment (F = 29.31, P less than 0.001 and F = 11.20, P less than 0.001, respectively). There were no significant changes in plasma sodium concentration or osmolality in response to the treatment (P greater than 0.05). The furosemide-treated horses consumed 126 +/- 14.8 g salt, significantly more than when they were given the control injection (94.5 +/- 9.8 g; t = 2.22, P = 0.05). In response to furosemide, horses lost 962 +/- 79.7 and consumed 2,170 +/- 5 meq sodium; however, compared with control, they lost 955 meq more sodium and ingested only 570 meq more sodium, so they were undercompensating for natriuresis. The furosemide-treated horses drank 9.6 +/- 0.8 kg of water, significantly more than when they received the control injection (6.4 +/- 0.8 kg; t = 6.9, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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Stahlbaum, C. C., & Houpt, K. A. (1989). The role of the Flehmen response in the behavioral repertoire of the stallion. Physiol. Behav., 45(6), 1207–1214.
Abstract: The role of the Flehmen response in equine behavior was investigated under field and laboratory conditions. In Experiment 1, a field study made of five stallions on pasture with between three and eighteen mares each during the season indicated the following: 1) The Flehmen response was most frequently preceded by nasal, rather than oral, investigation of substances; 2) The stallions' rate of Flehmen varied with the estrous cycles of the mares; 3) The rate of Flehmen response did not show a variation with time of day; and 4) The Flehmen response was most frequently followed by marking behaviors rather than courtship behaviors. The results suggest that the Flehmen response is not an immediate component of sexual behavior, e.g., courtship of the stallion but may be involved in the overall monitoring of the mare's estrous cycle. Therefore the Flehmen response may contribute to the chemosensory priming of the stallion for reproduction. In Experiment 2 stallions were presented with urine or feces of mares in various stages of the reproductive cycle as well as with their own or other males' urine or feces. The occurrence of sniffing and Flehmen was used to determine the discriminatory ability of the stallions. Stallions can differentiate the sex of a horse on the basis of its feces alone, but cannot differentiate on the basis of urine. This ability may explain the function of fecal marking behavior of stallions.
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Kharazyan, F., Hassani, A., Ahmadinejad, M., & Houpt, K. A. (2008). The response of horses to predator stimuli. In IESM 2008.
Abstract: It is unknown whether or not wild horses“ instinct has remained during their centuries of taming. The knowledge of this matter gives riders the opportunity of knowing more not only about horse behavior but also about horse and rider safety. In the current research we try to study behavior of the two Iranian horse breed (Asil & Caspian) in confrontation with stimuli from predators. We explored which kind of stimuli (olfactory stimuli accompanied by auditory stimuli) affects horses more. We groupe horses based on breed, sex and age. All horses are adult. The test area is a room that equipped with ventilator, speaker, and other facilities that needs. The time spent in the test area varies between 5 and 20 min .The experiments were designed to investigate behavioral responses (locomotive activity ( standing , walk , trot , and exploration), eliminatory behavior (defecation, urination)) and physiological responses (measure and record of adrenalin dosages in blood samples before and after facing to stimuli and measured blood”s glucose and cortisol too) of horses to novel auditory and olfactory stimuli.
We explored which kind of stimuli(Olfactory stimuli or auditory stimuli) affects horses more. The experiments were carried out under standardized conditions a total of 60 horses (30 Caspian ponies and 30 Asil horses), of different ages.
We investigated how horses respond to two predator animals" (wolf and Iranian leopard) olfactory and auditory stimulus. The olfactory stimuli were: A: Urine /feces stimuli, B: Fur-derived stimuli. And The auditory stimulus were sound of wolf and Iranian Leopard.
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Houpt, K. A., & Keiper, R. (1982). The position of the stallion in the equine dominance hierarchy of feral and domestic ponies. J. Anim Sci, 54(5), 945–950.
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Crowell-Davis, S., & Houpt, K. A. (1985). The ontogeny of flehmen in horses. Anim. Behav., 33(3), 739–745.
Abstract: Flehmen behaviour in Welsh pony (Equus caballus) mares and foals living on pasture was observed during 807 h of focal sampling. A series of flehmens performed at one site was defined as a flehmen incident. Colts exhibited flehmen incidents and performed flehmen more frequently during an incident than did fillies or mares. Filies exhibited flehmen incidents more frequently than did mares, but did not flehmen more frequently during an incident. Colts exhibited a peak frequency of performing flehmen and of flehmen incidents during weeks 1-4 with a subsequent linear decrease in frequency up to weeks 17-20. Usually, flehmen occurred without the subject having had direct contact of the nostrils, lips, or tongue with a possible stimulant. Twenty-six per cent of the flehmen incidents occurred during or after urination by another pony. Seven per cent of the incidents occurred during or after urination by the pony showing flehmen.
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Laut, J. E., Houpt, K. A., Hintz, H. F., & Houpt, T. R. (1985). The effects of caloric dilution on meal patterns and food intake of ponies. Physiol. Behav., 35(4), 549–554.
Abstract: In order to determine if horses will increase their intake in response to caloric dilution, four pony geldings were fed ad lib a mixed grain diet either undiluted (3.4 Mcal/kg of digestible energy) or diluted (wt/wt) with 25% sawdust (2.6 Mcal/kg) or with 50% sawdust (1.7 Mcal/kg). The mean daily caloric intake was 17,457 kcal (3.4 Mcal diet), 17,546 kcal (2.6 Mcal diet) and 12,844 kcal (1.7 Mcal). The mean time spent eating was 246 (3.4 Mcal), 351 (2.6 Mcal), and 408 (1.7 Mcal) minutes/day. Meal size increased and meal frequency decreased with increasing dilution. The median long survivorships of intermeal intervals were 6.4 min (3.4 Mcal), 3.95 min (2.6 Mcal) and 4.91 min (1.7 Mcal). Ponies responded to caloric dilution by increasing the volume of intake to maintain caloric intake when the diet had 25% diluent. When the diet was diluted by 50%, intake was increased, but not at a rate adequate to maintain caloric intake. However, the ponies were able to maintain body weight.
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Hogan, E. S., Houpt, K. A., & Sweeney, K. (1988). The effect of enclosure size on social interactions and daily activity patterns of the captive Asiatic wild horse (Equus przewalskii). Appl. Anim. Behav. Sci., 21(1-2), 147–168.
Abstract: Two herds of Przewalski horses at the Minnesota Zoological Garden were observed during 1980 in each of 2 enclosures that differed in size. The larger enclosure was a 3.4-ha pasture; the smaller enclosure was a 17 x 30-m grass-less pen. One herd was composed of a stallion, 3 adult mares and 2 foals. The other consisted of a stallion and 2 mares. All occurrences of aggression, mutual grooming and snapping were recorded, and 5-min scan-samples of the activity state of each horse were taken. The time budgets, frequency of aggression and frequency of mutual grooming differed significantly with enclosure size for both herds. More time was spent pacing and milling in the smaller enclosure, and the frequency of aggressions and of mutual grooming was also higher. Only the foals exhibited snapping; frequency of snapping did not vary with enclosure size. More time was spent feeding in the larger enclosure. Provision of hay in the smaller enclosure eliminated the differences in time spent feeding. A second study was conducted during the spring of 1984 in an intermediate-sized enclosure, 0.4 ha, a sub-division of the pasture on which the horses were kept in 1980. One herd consisted of a stallion, 2 mares and 2 yearlings; the other consisted of a stallion, 3 mares and a foal. One of the stallions and all of the mares were those studied in 1980, but that stallion and one of the mares were in different herds than they had been in 1980. The frequency of aggression was similar to that observed in 1980.
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Boyd, L. E., Carbonaro, D. A., & Houpt, K. A. (1988). The 24-hour time budget of Przewalski horses. Appl. Anim. Behav. Sci., 21(1-2), 5–17.
Abstract: A herd of 8 Przewalski horses were observed on pasture in summer. Fifteen-minute focal animal samples were used to determine the time budget of the horses during the periods 00.00-04.00, 04.00-08.00, 08.00-12.00, 12.00-16.00, 16.00-20.00 and 20.00-24.00 h EDT. The behavioral states recorded were feeding (grazing and eating grain), nursing, drinking, standing, stand-resting, self-grooming, mutual grooming, locomoting, playing, and lying laterally and sternally. The average number of behavioral states occurring per hour, and the defecation, urination, aggression and vocalization rates were also determined. Overall, the horses spent 46.4 +/- 5.9% of their time feeding, 1.3 +/- 0.1% nursing, 0.5 +/- 0.1% drinking, 20.6 +/- 5.4% standing, 15.7 +/- 3.2% stand-resting, 1.7 +/- 0.2% self-grooming, 2.2 +/- 0.7% mutual grooming, 7.4 +/- 1.0% locomoting, 1.2 +/- 0.3% playing, 1.2 +/- 0.5% lying laterally and 4.1 +/- 3.0% lying sternally. The horses averaged 45.2 +/- 5.8 behavioral states per hour, and 0.2 +/- 0.0 defecations, 0.3 +/- 0.0 urinations, 1.5 +/- 0.3 aggressions and 0.7 +/- 0.1 vocalizations per hour. The horses spent the greatest amount of time foraging between 20.00 and 04.00 h, when the temperatures were lower. They spent 68.2 +/- 2.2% of their time between 20.00 and 24.00 h feeding, but only 31.2 +/- 2.1% of their time feeding between 08.00 and 12.00 h. Recumbent rest was most common between 00.00 and 04.00 h. As temperatures rose during the daylight hours, the horses spent more time drinking and standing, rather than grazing. Stand-resting was the most common form of rest during the day. The horses exhibited the greatest number of activities per hour from 08.00 to 20.00 h. While standing in close proximity to one another during these hours, the horses exhibited the highest number of aggressions per hour (1.9-2.4).
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