Central neuropathology of equine grass sickness

• Published in: Acta neuropathologica 2001-08, Vol.102 (2), p.153-159
• Main Authors: HAHN, C. N, MAYHEW, I. G, DE LAHUNTA, A
• Format: Article
• Language: English
• Subjects: Age Factors; Animal diseases; Animal Nutritional Physiological Phenomena; Animals; Autonomic nervous system; Autonomic Nervous System Diseases - complications; Autonomic Nervous System Diseases - pathology; Autonomic Nervous System Diseases - veterinary; Biological and medical sciences; Brain stem; Brain Stem - pathology; Brain Stem - physiopathology; Cell Count; Cranial nerve nuclei; Cranial nerves; Cranial Nerves - pathology; Cranial Nerves - physiopathology; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Dysautonomia; Grass sickness; Horse Diseases - pathology; Horse Diseases - physiopathology; Horses; Linear Models; Medical sciences; Motor Neuron Disease - etiology; Motor Neuron Disease - pathology; Motor Neuron Disease - veterinary; Motor neurons; Motor Neurons - pathology; Nervous system (semeiology, syndromes); Neurology; Parasympathetic nervous system; Plant Poisoning - pathology; Plant Poisoning - physiopathology; Plant Poisoning - veterinary; Poaceae - poisoning; Reticular Formation - pathology
• ISSN: 0001-6322; 1432-0533
• DOI: 10.1007/s004010000289

Equine grass sickness (EGS) is an acquired disease of unknown aetiology affecting horses kept at grass. The disease is characterised by postganglionic sympathetic and parasympathetic neuronal pathology and is categorised as a dysautonomia. This study undertook a systematic examination of brain stem cranial nerve nuclei in 59 cases of EGS. Pathology consisting of neuronal chromatolysis was most consistently noted in the lower motor neurons of the general visceral efferent nucleus of CN III and X and the general somatic efferent nuclei of CN III, V, VII and XII. The prevalence of chromatolysis differed significantly between the diagnostic categories and was inversely related to the age of the animal. Duration of disease had a small but significant negative effect on the proportion of nuclei with chromatolytic neurons in chronic cases. The distribution of chromatolytic neurons is unlike that reported in any other equine or human disease; however, it appears to be equivalent to that in other animals with primary dysautonomias. EGS should be classified as a multisystem disease.