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Journal of veterinary internal medicine2019; 33(5); 2302-2311; doi: 10.1111/jvim.15567

A study of residual lesions in horses that recovered from clinical signs of chronic equine dysautonomia.

Abstract: Equine dysautonomia (ED) causes degeneration and loss of autonomic neurons. Approximately 50% of chronic cases recover, but it is unclear how they survive neuronal loss. Objective: To assess lesions, autonomic neuron numbers, interstitial cells of Cajal (ICC), and neurodegeneration in recovered cases. Methods: Thirteen cases (group ED), euthanized 10.3 ± 5.2 (1-16) years from diagnosis and 6 age-matched controls (group C). Methods: Prospective, case control; routine post mortem examination, neuron counts in peripheral and enteric ganglia and immunohistochemical assessment of neural networks (Protein gene product [PGP] 9.5), ICC (c-kit), and neurodegeneration (beta-amyloid precursor protein and ubiquitin) in intestine. Results: Postmortem findings in group ED were small intestinal dilation (4/12, 33%) and muscular hypertrophy (4/12, 33%), and gastric mucosal hypertrophy (3/11, 27%) and ulceration (4/11, 36%). Neuron density was lower in group ED (mean 39% lower for cranial cervical ganglion [P < .001], median 44% lower in celiacomesenteric ganglion [P = .01]). In intestine, neuronal depletion was worst in ileum (median 100% lower in submucosal plexus [P < .001], 91% lower in myenteric plexus [P = .004]). Group ED had less PGP 9.5 staining in ileal myenteric plexus (mean 66% lower [P = .04]) and circular muscle (median 75% lower [P = .006]). In ileum, there was less c-kit staining in myenteric plexus (median 57% lower [P = .02]) but not muscularis externa. Beta-amyloid precursor protein and ubiquitin results were not indicitive of neurodegeneration. Conclusions: Intact ICC in muscularis externa might help maintain motility after neuronal loss. Treatment supporting ICC function warrants investigation.
© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2019-07-22 PubMed ID: 31332854PubMed Central: PMC6766533DOI: 10.1111/jvim.15567Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Equine dysautonomia (ED), a condition that leads to the deterioration and loss of neurons responsible for regulating involuntary bodily functions in horses, was examined to understand how some horses recover despite significant neuron loss. This research uncovered evidence of incomplete recovery in horses that survived ED, with the nervous system still showing signs of damage.

Overview of the Research

The research utilized a prospective, case control design and included thirteen horses (group ED) that recovered from clinical signs of ED and six healthy, age-matched control horses (group C). The recovered horses had been diagnosed with ED roughly 10.3±5.2 years prior. The methods used in this research involved post-mortem examination, with the goal to assess lesions, autonomic neuron counts, interstitial cells of Cajal (ICC), and signs of neurodegeneration.

Methods

  • Post mortem examination: Routine examination of deceased animals to understand underlying issues.
  • Neuron counts: Counting of neurons in peripheral and enteric ganglia to gauge the extent of neuron loss.
  • Immunohistochemical assessment: Study of protein markers to trace neural networks and identify ICC and neurodegeneration within the intestine. Specifically, the protein gene product (PGP) 9.5, ICC (c-kit), and markers of neurodegeneration (beta-amyloid precursor protein and ubiquitin) were assessed.

Result Findings

The results showed several post-mortem findings in the ED group, including small intestinal dilation, muscular hypertrophy, and gastric mucosal hypertrophy and ulceration. Neuron density was significantly lower in the ED group compared to the control group, with the density decrease particularly dramatic in the ileum portion of the intestine.

Outcome and Conclusion

Despite neuronal loss, the ICC in the muscularis externa, which are involved in maintaining gut motility, remained intact. This possibly explains how horses are able to survive and maintain gastrointestinal function after experiencing ED. However, the researchers did caution that beta-amyloid precursor protein and ubiquitin results did not indicate active neurodegeneration. This study suggested that further investigation into treatments that support the function of ICC may be beneficial for horses recovering from ED.

Cite This Article

APA
Milne EM, Pirie RS, Hahn CN, Del-Pozo J, Drummond D, Moss S, McGorum BC. (2019). A study of residual lesions in horses that recovered from clinical signs of chronic equine dysautonomia. J Vet Intern Med, 33(5), 2302-2311. https://doi.org/10.1111/jvim.15567

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 33
Issue: 5
Pages: 2302-2311

Researcher Affiliations

Milne, Elspeth M
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
Pirie, R Scott
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
Hahn, Caroline N
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
Del-Pozo, Jorge
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
Drummond, Dawn
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
Moss, Sharon
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.
McGorum, Bruce C
  • Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Midlothian, United Kingdom.

MeSH Terms

  • Amyloid beta-Protein Precursor / analysis
  • Animals
  • Biomarkers
  • Case-Control Studies
  • Disease Progression
  • Enteric Nervous System / pathology
  • Horse Diseases / pathology
  • Horses
  • Interstitial Cells of Cajal
  • Intestines / cytology
  • Intestines / innervation
  • Neurons / pathology
  • Primary Dysautonomias / pathology
  • Primary Dysautonomias / veterinary
  • Prospective Studies
  • Proteins / analysis
  • Proto-Oncogene Proteins c-kit / analysis
  • Ubiquitin / analysis

Conflict of Interest Statement

Authors declare no conflict of interest.

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Citations

This article has been cited 1 times.
  1. Atkins CN, Hahn CN, McGorum BC. Comparison of Dysautonomia Across Species: Current Knowledge and Future Research Opportunities. J Vet Intern Med 2025 Jul-Aug;39(4):e70140.
    doi: 10.1111/jvim.70140pubmed: 40525668google scholar: lookup
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