Effect of Noise Stress on Heart rate and Changes in Blood Characteristics in the Horse

Abstract

The heart rate and changes in hematological characteristics were examined to determine the effect of noise on the horse . The results obtained were compared with those from experiments on epirenamine administration and exercises . The following conclusions were drawn. 1. There was a marked increase in heart rate when a horse was exposed to a big noise about 90-100 phons in loudness . 2. Red blood count, hemoglobin content, packed-cell volume, and white blood count increased after the exposure, but erythrocyte sedimentation rate, blood water content, and eosinophilis decreased. 3. Subcutaneous injection with 8 mg of epirenamine exhibited a similar effect to that of exposure to noise. It had, however, slightly less remarkable effect on the heart rate, but a slightly stronger effect on hematological characteristics, than the noise. 4. Changes in heart rate and hematological characteristics after enforced exercises were variable depending on the strength of exercises . However, they usually showed essentially the same tendency as mentioned above . 5. The above-mentioned changes observed after the epirenamine administration or enforced exercises can be assumed to indicate that the balance of the autonomic nerves is inclined more to sympathicotonia . With the same philosophy, they can also be assumed to indicate that exposure to noise leads a horse to the similar balance of the autonomic nervous system.