Topic:Autonomic Nervous System
The autonomic nervous system (ANS) in horses is a component of the peripheral nervous system responsible for regulating involuntary physiological functions, including heart rate, respiratory rate, digestion, and thermoregulation. It consists of two main divisions: the sympathetic nervous system, which prepares the body for 'fight or flight' responses, and the parasympathetic nervous system, which supports 'rest and digest' activities. The ANS helps maintain homeostasis and allows horses to respond to environmental changes and stressors. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and impact of the autonomic nervous system on equine behavior, performance, and health.
Clinical equine dysautonomia and autonomic neuron damage. Damage to the neurons of selected autonomic ganglia was quantified in relation to the severity of the clinical signs shown in acute, subacute and chronic cases of dysautonomia (grass sickness). No connection between the clinical severity of acute or subacute dysautonomia and the amount of neuronal damage in the superior cervical, stellate and coeliaco-mesenteric ganglia could be demonstrated. However, a higher proportion of normal neurons were found in chronic cases. Jejunal submucosal neuronal damage was correlated with clinical severity but further work is required to confirm this finding an...
Long term ECG recording with Holter monitoring in clinically healthy horses. The electrocardiogram of 9 horses was continuously recorded for 24 h with Holter monitoring to examine the variations in heart rate and rhythm during daily routine procedures and at night. Three horses had transient sinus bradycardia, and 3 had periods of sinus tachycardia. Heart blocks were detected in 3 horses, and all horses had periods of sinus arrhythmia. These changes in the heart rate and rhythm were apparently caused by variations in autonomic nervous system tone and they are probably "normal" findings in resting, undisturbed horses. Ventricular premature depolarisations were not obser...
Naloxone-induced abdominal distress in the horse. Endogenous opioid peptides have been implicated in the regulation of pain perception, behaviour, gastrointestinal activity and other physiological responses. However, the functional role of these peptides in the horse has yet to be elucidated. The opioid antagonist, naloxone, is often administered to infer endogenous opioid effects. In the present study, naloxone (0.75 mg/kg bodyweight) was administered to eight Thoroughbred racehorses and a number of behavioural and autonomic responses were measured. Naloxone produced rapid onset diarrhoea, restlessness, abdominal checking, tachycardia, tachy...
The immunocytochemical distribution of seven peptides in the spinal cord and dorsal root ganglia of horse and pig. The distribution of calcitonin gene-related peptide (CGRP), enkephalin, galanin, neuropeptide Y (NPY), somatostatin, tachykinins and vasoactive intestinal polypeptide (VIP) was compared in cervical, thoracic, lumbar and sacral segmental levels of spinal cord and dorsal root ganglia of horse and pig. In both species, immunoreactivity for the peptides under study was observed at all segmental levels of the spinal cord. Peptide-immunoreactive fibres were generally concentrated in laminae I-III, the region around the central canal, and in the autonomic nuclei. A general increase in the number of i...
Relation of intrinsic heart rate and autonomic nervous tone to resting heart rate in the young and the adult of various domestic animals. Intrinsic heart rate (IHR) and autonomic nervous tone (ANT) were measured using the young and the adult of horses, cows, pigs, goats and chickens in order to elucidate species differences in a decrease of resting heart rate (RHR) with growth or age. The IHR and ANT were estimated from the changes in heart rate after the administration of atropine and/or propranolol. The IHR in all species decreased progressively with an increase in body weight from young to adult, and moreover the ANT altered toward the direction of parasympathetic predominance by a decrease in sympathetic tone and/or an incre...
Dose-related effects of detomidine on autonomic responses in the horse. 1. Detomidine is a novel veterinary sedative analgesic which is thought to act by stimulation of alpha 2 adrenoreceptors. The present study was undertaken to determine the direction, time course, and dose-response relationship of detomidine on specific autonomic responses in the unanaesthetized horse. 2. Detomidine was administered intravenously to eight adult thoroughbred racehorses at doses of 0.010-0.040 mg kg-1, according to a double-blind Latin square crossover design. Cardiac and respiratory rates, pupil diameter and rectal temperature were monitored for 180 min postinjection. 3. Detomid...
Dose-related effects of fentanyl on autonomic and behavioral responses in performance horses. The dose-related effects of intravenously administered fentanyl (0.010, 0.005, 0.0025 mg/kg) and saline were studied in mature performance horses using a rigorous experimental protocol. Fentanyl produced a dose-related prolongation of the skin twitch reflex latency but did not increase the hoof withdrawal reflex latency. Dose related increases in stepping frequency, cardiac and respiratory rats were observed following fentanyl, while changes in rectal temperature and pupil area were not. These data indicate that fentanyl, a prototypic mu-agonist, produces a syndrome characterized by analgesia,...
[Motor goals of therapeutic horseback riding for cerebral palsied children (author’s transl)]. The article reviews in a critical survey the current opinions on the possibilities of improving the motor functions of cerebral palsied children with the help of riding therapy. Furthermore, the essential motor difficulties with spasm, athetosis and ataxia are described. It is demonstrated that only a small number of these typical difficulties can be tackled by means of riding therapy and that some key problems, particularly encountered by the spastics, cannot be solved. If, despite these facts, the favourable effects of riding on the cerebral palsied cannot be denied, then this must be attrib...
Hemodynamics and myocardial function during acute hypoxia in the pony. Hemodynamics and myocardial contractility were evaluated in 6 unanesthetized ponies during hypocapnic and isocapnic hypoxia and during hypocapnic hypoxia after beta adrenergic blockade with propranolol. Hypocapnic hypoxia, with a mean arterial oxygen pressure (PaO2) of 41.9 mm of Hg, produced a decrease in stroke index and an increase in heart rate, with no change of cardiac index. A moderate increase in left ventricular contractility occurred during hypocapnic hypoxia. Beta adrenergic blockade abolished changes in nearly all indices of left ventricular contractility during hypocapnic hypoxia,...