| Home | << 1 >> |
|
McCann, J. S., Heird, J. C., Bell, R. W., & Lutherer, L. O. (1988). Normal and more highly reactive horses. II. The effect of handling and reserpine on the cardiac response to stimuli. Appl. Anim. Behav. Sci., 19(3-4), 215–226.
Abstract: A split-plot experiment evaluated the effect of handling and reserpine on the autonomic heart-rate response of yearling horses to various stimuli. The emotionality levels of 32 Quarter-Horse yearlings were rated by 4 experienced horsemen on a scale from 1 to 4 (1 = most nervous and erratic disposition; 4=quiet disposition). The yearlings were subsequently classified and penned based on their emotionality level; normal or nervous. Within each emotionality group, one-half the yearlings were handled daily for 14 days and the other one-half remained free in the pens. Following the handling treatment, every yearling was individually exposed to a series of stimuli, while the heart rate was monitored via a radio-telemetry system. A second treatment, reserpine, was subsequently given intramuscularly (0.005 mg/kg body weight) to one-half the yearlings of each treatment combination of emotionality and handling. The heart rate of the yearlings to the same series of stimuli previously employed was determined at 24 and 120 h and 16 days following the reserpine injection. Summarizing the results, the handled yearlings tended to exhibit lower heart rates with the handling stimulus, but the heart rate with a more novel stimulus was not affected by the previous handling treatment. Reserpine tended to suppress the heart rate of the unhandled group during the presence of a handler, but the permanency of this effect was not evident 16 days after the drug was administered. The reserpine-treated groups tended to exhibit the lowest heart-rate response to stimuli during the 120-h test-day following the administration of the drug. Heart-rate responses to the stimuli were not different between the normal and nervous yearlings.
|
|
McCann, J. S., Heird, J. C., Bell, R. W., & Lutherer, L. O. (1988). Normal and more highly reactive horses. I. Heart rate, respiration rate and behavioral observations. Appl. Anim. Behav. Sci., 19(3-4), 201–214.
Abstract: Thirty-two Quarter horse yearlings were utilized in a split-plot experiment to establish behavioral tendencies for two levels of emotionality; normal and a more highly reactive level of emotionality termed nervous. Four observers who were experienced with horses scored the yearlings on an emotionality scale from 1 to 4, with 1 representing the highly nervous yearlings and 4 representing the quiet yearlings. Emotionality evaluations were based upon the response of the yearlings to a standard regimen of standing in a chute, being identified and being released from the chute. The inter-rater reliability coefficients were 0.90 for the normal yearlings and 0.65 for the nervous yearlings, indicating that the raters agreed less when evaluating the nervous yearlings. Yearling heart rates in the chute were correlated (r = -0.54, P<0.002) with the average emotionality score. Observational data on behavior collected 2 days following the emotionality scoring procedure indicated that the normal yearlings maintained a greater (P<0.001) individual distance than the nervous yearlings. From an activity summary, the normal yearlings spent 10.9% of the time lying down (LD), 79.1% standing (S), 9.6% walking or trotting (WT) and 0.4% of the time cantering or galloping (CG). The nervous yearlings spent 5.7% of the observational periods LD, 79.2% S, 11.7% WT and 3.4% CG. The nervous yearlings tended to have a higher overall activity index level than did the normal yearlings. Results indicate horses of different emotionality levels exhibited different behavioral patterns.
|