Enteric neuropathy in horses with grass sickness

Scholes, S. F. E.; Vaillant, Camille; Peacock, P. R.; Edwards, Glenn S.; Kelly, D. F.

doi:10.1136/vr.132.26.647

Cited by 45 publications

(46 citation statements)

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“…It is not known whether neuronal function differs between the two parts of the small intestine and, if so, whether those neurons with one particular function are mainly in the jejunum or the ileum. This may be of importance in dysautonomia, in which ileal neurons appear to be more extensively damaged than jejunal neurons (Scholes et aL, 1993;Doxey et aL, 1995).…”

Section: Discussionmentioning

confidence: 98%

“…Equine dysautonomia is a disease of unknown aetiology which results in destruction of large numbers of neurons in both the myenteric and submucosal plexuses (Scholes et aL, 1993). Investigation of this important disease requires that the enteric nerve cells are examined in detail to discover how their morphology, number and distribution have been altered.…”

Section: Introductionmentioning

confidence: 99%

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The equine enteric nervous system — Neuron characterization and distribution in adults and juveniles

et al. 1995

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A study of myenteric and submucosal plexuses was undertaken in the jejunum and ileum of horses and ponies in which no clinical or pathological evidence of intestinal abnormality was apparent. Complete transverse sections of the intestine, stained by a modified haematoxylin and eosin method, were examined using up to 20 sequential sections per animal. Information was gathered from adult, juvenile and fetal equidae. In adults, the longitudinal muscle layers were thinner than the circular muscle layers and the ileum had thicker layers compared to the jejunum. In adults, the submucosal plexus had more neurons per section than the myenteric plexus by mean ratios of 1:3 in the jejunum and 1:1.9 in the ileum. In juveniles, the ratios were respectively 1:1.8 and 1:1.5 and in the fetus 1:2.5 and 1:1.3. The three-dimensional distribution of neurons in both plexuses varied from animal to animal and no consistent pattern was observed. Groups of neurons contained between one and 42 cells per section examined and their length in a cranio-caudal direction varied from 10 to over 100 microns. There were few statistical differences observed between the cranial, middle and caudal portions of either the jejunum or the ileum when neuron groups or neuron numbers per section were examined in 10 adult animals.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

The equine enteric nervous system — Neuron characterization and distribution in adults and juveniles

et al. 1995

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“…Histological examination of autonomic ganglia shows evidence of neuronal degeneration and ultimately depletion (Obel, 1955;Gilmour, 1973), and it is thought that a neurotoxin may be involved in the aetiology (Pollin and Griffiths, 1992). Neuronal damage is also observed in the enteric nervous system (Sabate et al, 1983) with the greatest damage to neurons in the ileum (Scholes et al, 1993). Motility of equine small intestine from clinically normal tissues has previously been studied by Ruckebusch and colleagues (1971).…”

Section: Introductionmentioning

confidence: 94%

Cholinergic activity of intestinal musclein vitro taken from horses with and without equine grass sickness

Murray¹,

Cottrell²,

Woodman

1994

Vet Res Commun

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Equine grass sickness (EGS) is a pan-dysautonomia of horses that involves central and peripheral neuronal degeneration and ultimately depletion. This is the first reported functional study on the motility of equine intestine taken immediately post mortem from horses with EGS. Strips of smooth muscle from the small intestine of healthy and EGS-affected horses were suspended in an organ bath and their motility was measured isometrically. The activity of the cholinergic system was studied. Physostigmine enhanced the motility of all muscle strips. Tissues taken from horses suffering from acute grass sickness (AGS) had the longest latency before a measurable response could be obtained (p < 0.05). The ileum appeared to be damaged by EGS to a greater extent than the duodenum. For the duodenal strips the enhanced rate of spontaneous contractions was significant (p < 0.05) for both normal tissue and that affected by grass sickness but this was not the case for the ileal strips. Muscarinic receptor sensitivity investigation using bethanecol suggested a hypersensitivity of receptors with AGS material.

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“…4,5 Equine dysautonomia is characterized by neuronal degeneration resembling chromatolysis and a reduction in the number of neurons in the prevertebral and paravertebral autonomic ganglia and the enteric plexuses. 3,6 Neuronal damage in the gastrointestinal tract is not uniform, and although the ileum is usually the most severely affected, 8 the jejunum can be more severely affected than the ileum in a minority of cases. 3 Histopathologic examination of the autonomic ganglia postmortem is considered the gold standard method for diagnosis.…”

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confidence: 99%

Evaluation of Formalin-Fixed Ileum as the Optimum Method to Diagnose Equine Dysautonomia (Grass Sickness) in Simulated Intestinal Biopsies

et al. 2010

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Abstract. Equine dysautonomia, or grass sickness, is a frequently fatal disease of unknown etiology, manifested as poor gastrointestinal motility and colic as a result of degenerative changes in the autonomic nervous system. Examination of ileal biopsies collected at laparotomy is currently the best antemortem diagnostic method to distinguish equine dysautonomia from colic cases, which can present with similar signs, but their value has not been previously critically evaluated. Using simulated biopsies collected postmortem from 23 cases of equine dysautonomia and 11 of colic, the sensitivity and specificity of 1-cm long, formalinfixed ileal biopsies was 100% for the diagnosis of equine dysautonomia. There was therefore no advantage to using larger biopsies or examining jejunum either in addition to or instead of ileal biopsies. Furthermore, although cryostat sections of ileum, 1-cm long, had a sensitivity of 100%, the specificity was only 73%, meaning that 27% of cases would have been misclassified, resulting in unnecessary euthanasia. Increasing the size of the cryostat or examining jejunum in addition to ileum cryostat sections did not significantly improve the specificity. Results of the current study indicate that in diagnostic practice, 1-cm long, formalin-fixed biopsies are likely to be the most suitable for accurate diagnosis, despite the slower turnaround time compared with cryostat sections.

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Enteric neuropathy in horses with grass sickness

Cited by 45 publications

References 0 publications

The equine enteric nervous system — Neuron characterization and distribution in adults and juveniles

The equine enteric nervous system — Neuron characterization and distribution in adults and juveniles

Cholinergic activity of intestinal musclein vitro taken from horses with and without equine grass sickness

Evaluation of Formalin-Fixed Ileum as the Optimum Method to Diagnose Equine Dysautonomia (Grass Sickness) in Simulated Intestinal Biopsies

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