Hematology, biochemistry, and physiology of environmentally stressed horses

This study involved a group of horses that were snowbound during winter in the Alaska Mountain Range. The severe nutritional and environmental stresses offered a unique opportunity to study the effects of these stressors on the physiology of the horse. The horses were characterized for their basic hematologic, biochemical, and physical condition. Body water contents, body water kinetics, blood volumes, and plasma iron clearance rates were determined using radioisotope methods. These analyses were repeated after the horses were given liquid water, as opposed to snow, and once again after they were given liquid water and feed ad libitum. No significant differences in the measured physiological parameters were found between groups of horses on liquid water versus snow or limited feed versus ad libitum feed except that body water kinetics were directly related to feed intake. Physiological values obtained in this study were compared with literature values for non-stressed horses and no deviation from the normal ranges were found. The results may be interpreted as indicating a remarkable physical stamina for the horse.

Electromyoenterography during normal gastro-intestinal activity, painful or non-painful colic and morphine analgesia, in the horse

The electrical potentials were recorded from the antrum, the duodenum, the ileum and the first part of the colon of ponies under (a) normal resting conditions, (b) during nonpainful colic and (c) after intravenous morphine administration. The normal pony, at rest, had five contractions of the antrum per minute. On the small intestine, the basal electrical activity decreased from the duodenum (14-15/min) to the ileum (10-11/min). The small bowel also had three types of motility: peristaltic waves, rhythmic segmentations and random contractions. On the colon, bursts of potentials indicating intense motor activity occurred at the rate of 20 to 30 per hour. Morphine given intravenously (IV) greatly increased the frequency of the electrical potentials of the antrum and the longitudinal bands of the colon. During non-painful colic, hyperactivity of the cranial small intestine was continuous. Spasms of the jejunum occurred every minute and could not be relieved by morphine (IV). When colic was painful, jejunal spasms announced the crisis of intense abdominal pain. After morphine (IV) the spasms and pain disappeared; the jejunum remained hyperactive, the motility of the colon was increased while the antrum became quiet.