The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness.
Abstract: Clinical evidence of motor neuron involvement in equine grass sickness (EGS) has not been reported. Objective: Quantitative electromyography (EMG) analysis can elucidate subtle changes of the lower motor neuron system present in horses with EGS, performed ante mortem. Methods: Fourteen horses diagnosed clinically with acute, subacute or chronic EGS were examined and quantitative EMG performed. Previously published data on healthy horses and horses with proven lower motor neuron disease (LMND) were used as controls. In 8 horses post mortem examination was performed, and in 7 muscle biopsies of the lateral vastus muscle underwent histopathology and morphometry. Results: Clinical electrophysiological evidence of neuropathy was present in 12 horses. Analysis of data from the first 4 horses resulted in 95% confidence intervals (CI) of nontransformed data for motor unit action potential (MUP) duration in subclavian, triceps and lateral vastus muscle of 11.0-13.7, 14.8-20.3 and 12.2-17.2 msecs, respectively, and for MUP amplitude 291-453, 1026-1892 and 957-1736 microV, respectively. For number of phases the 95% CI was 3.6-4.4, 2.9-3.6 and 2.9-3.4, respectively, and for number of turns 5.0-6.5, 4.3-5.3 and 3.7-4.6, respectively. No changes in duration of insertional activity were measured. Pathological spontaneous activity was observed in all horses. EGS as evidenced by degenerative changes in the autonomic ganglia in combination with minor degenerative changes of the spinal lower motor neurons was observed on post mortem examination in all 8 available autopsies. In muscle biopsies of 4 out of 7 horses changes consistent with slight neurogenic atrophy were found. Conclusions: EMG results demonstrated the presence of a neuropathy of skeletal muscles in all horses suspected to have EGS. The combination of clinical and electrophysiological evidence may aid differential diagnosis of neurogenic disease in cases of weight loss and colic.
Publication Date: 2006-05-19 PubMed ID: 16706277DOI: 10.2746/042516406776866309Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Autopsy
- Clinical Examination
- Clinical Findings
- Clinical Pathology
- Diagnosis
- Disease Diagnosis
- Disease Etiology
- Equine Health
- Equine Motor Neuron Disease
- Grass Sickness
- Histopathology
- Horses
- Morphometry
- Musculoskeletal System
- Myography
- Neurological Diseases
- Neuropathy
- Pathology
- Veterinary Medicine
- Veterinary Procedure
- Veterinary Research
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.
This research explores the use of quantitative electromyography (EMG) to reveal previously undetectable motor neuron changes in horses suffering from equine grass sickness (EGS). The study found that all diagnosed horses showed EMG results indicating neuropathy of skeletal muscles, providing additional evidence that may assist in the differential diagnosis of EGS in symptoms similar to weight loss and colic.
Research objectives and methods
- The study aimed to identify minute changes in the lower motor neuron system in horses suffering from EGS using quantitative EMG. The research was conducted on living horses (ante mortem).
- Fourteen horses diagnosed with EGS in its various forms (acute, subacute or chronic) underwent quantitative EMG exams.
- Control data was utilized from healthy horses and horses with diagnosed lower motor neuron disease (LMND).
- 8 of the horses also had a post-mortem exam, and 7 of them had muscle biopsies of the lateral vastus muscle to undergo histopathology and morphometry.
Research findings
- The EMG revealed clinical electrophysiological evidence of neuropathy in twelve of the horses.
- Specific data related to the motor unit action potential (MUP) duration and amplitude, number of phases, and number of turns were calculated for different muscles, providing a base of comparison for future studies.
- No changes were identified in insertional activity duration, however pathological spontaneous activity was observed in all horses.
- All 8 horses that went through post-mortem examination showed EGS evident by degenerative changes in the autonomic ganglia along with minor degenerative changes of the spinal lower motor neurons.
- Out of 7 biopsied horses, four showed changes consistent with slight neurogenic atrophy.
Conclusion
- All horses suspected of EGS displayed evidence of a neuropathy of the skeletal muscles as shown by the EMG results.
- These findings combined with clinical symptoms can potentially assist in differential diagnosis in cases showing signs of weight loss and colic, commonly associated with neurogenic diseases in horses.
Cite This Article
APA
Wijnberg ID, Franssen H, Jansen GH, van den Ingh TS, van der Harst MR, van der Kolk JH.
(2006).
The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness.
Equine Vet J, 38(3), 230-237.
https://doi.org/10.2746/042516406776866309 Publication
Researcher Affiliations
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, 3584 CM, The Netherlands.
MeSH Terms
- Action Potentials
- Acute Disease
- Animals
- Autonomic Nervous System Diseases / diagnosis
- Autonomic Nervous System Diseases / pathology
- Autonomic Nervous System Diseases / physiopathology
- Autonomic Nervous System Diseases / veterinary
- Biopsy
- Case-Control Studies
- Chronic Disease
- Diagnosis, Differential
- Electromyography / methods
- Electromyography / veterinary
- Female
- Horse Diseases / diagnosis
- Horse Diseases / pathology
- Horse Diseases / physiopathology
- Horses
- Male
- Muscle, Skeletal / physiopathology
Citations
This article has been cited 3 times.- Story MR, Haussler KK, Nout-Lomas YS, Aboellail TA, Kawcak CE, Barrett MF, Frisbie DD, McIlwraith CW. Equine Cervical Pain and Dysfunction: Pathology, Diagnosis and Treatment. Animals (Basel) 2021 Feb 6;11(2).
- Zakia LS, Palumbo MIP, Teixeira RBC, Resende LAL, Soares MP, de Oliveira-Filho JP, Amorim RM, Borges AS. Neuromyotonia in a horse. J Vet Intern Med 2019 Jan;33(1):287-291.
- McGorum BC, Davey T, Dosi MCM, Keen JA, Morrison LR, Pirie RS, Shaw DJ, Harris JB. Equine grass sickness is associated with major abnormalities in the ultrastructure of skeletal neuromuscular junctions. Equine Vet J 2025 Jan;57(1):193-202.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
