FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Equine veterinary journal2025; doi: 10.1111/evj.14506

Motor pathway evaluation by transcranial magnetic stimulation in Swedish horses with acquired equine polyneuropathy.

Abstract: Acquired equine polyneuropathy in Nordic horses (AEP) is the most prevalent equine polyneuropathy in Norway, Sweden, and Finland and is characterised by pelvic limb knuckling due to metatarsophalangeal extension dysfunction. Objective: To evaluate the function of descending motor pathways in AEP using transcranial magnetic stimulation (TMS). Methods: An analytical, observational cohort design. Methods: Clinical findings and TMS results of 20 horses from an AEP outbreak in Sweden were evaluated at 5-month intervals. Latency time (LT) in milliseconds (ms) between coil discharge and onset of muscle potential was recorded for thoracic and pelvic limbs. Results: Fourteen affected horses showed knuckling, 2 horses showed lameness, and 6 horses were neurologically sound and showed no clinical signs at the first visit. Thirteen of 14 neurologically affected horses had improved clinically 5 months later, four no longer showed knuckling. Motor neurological dysfunction with increased LT was confirmed by TMS in all 14 affected horses at both visits. Mean difference in LT from normalised reference values (ΔLT) in the pelvic limbs of affected horses was +12.95 ms (+38%) at the first examination (1.9-29.6 ms; SD 1.23; n = 14), and +8.1 ms (+24%) 5 months later (1.0-18.9 ms; SD 1.21; n = 14), cutoff >0.8 ms. Eleven of 14 affected horses also presented delayed TMS responses in the thoracic limbs, with up to 14% ΔLT increase. Neurologically sound, non-lame horses (n = 8) showed mean ΔLT -0.5 ms (-1.8 to 0.2 ms; SD = 0.64) in pelvic, and -0.35 ms (range, -0.7 to 0 ms; SD = 0.26; n = 8) in thoracic limbs, cutoff >0.2 ms. Conclusions: Examinations were only repeated once. Conclusions: This study confirms the involvement of motor pathways in AEP and adds to the previously established involvement of sensory nerve fibres. Sensory and motor involvement contributes to the mismatch of ascending and descending nerve signals and to the clinical manifestations. TMS may be useful in evaluating clinical and subclinical cases of AEP.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
Get Full Text
Publication Date: 2025-04-21 PubMed ID: 40257381DOI: 10.1111/evj.14506Google 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.
LinkedInCopy
  • Journal Article

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 study investigates the function of motor pathways in horses affected by Acquired Equine Polyneuropathy (AEP), a condition prevalent in the Nordic region. It uses Transcranial Magnetic Stimulation (TMS) to analyze 20 horses from an outbreak in Sweden.

Research Methodology

  • This study undertakes an analytic, observational cohort design.
  • The researchers conducted clinical examinations and TMS assessments on 20 horses affected by an AEP outbreak over a period of five months.
  • They utilized TMS to measure the latency time (LT) between the coil discharge and the onset of the potential muscular response within the horses.
  • The study evaluated these readings in both thoracic and pelvic limbs.

Results

  • Of the 20 horses evaluated, 14 demonstrated signs of knuckling, 2 showed lameness, and 6 showed no clinical signs at the initial visit.
  • After five months, 13 of the 14 horses affected neurologically showed clinical improvements, with 4 no longer showing signs of knuckling.
  • All 14 neurologically affected horses, however, exhibited increased LT confirmed by TMS in both visits.
  • There was an increase of 38% in LT in the initial examination and 24% in the follow-up examination for the affected horses’ pelvic limbs.
  • Eleven of the 14 affected horses also showed delayed TMS responses in their thoracic limbs, with up to 14% ΔLT increase.
  • The neurologically sound horses, who demonstrated no lameness or clinical signs, showed minuscule variations in their LT response.

Conclusions

  • The study confirmed the involvement of motor pathways in AEP.
  • This research adds to the existing knowledge about the involvement of sensor nerve fibers, indicating a discrepancy in the transmission of ascending and descending nerve signals, which contributes to the observed clinical symptoms in AEP.
  • The use of TMS can be valuable in evaluating clinical and subclinical cases of AEP.

Cite This Article

APA
May A, Hanche-Olsen S, Goehring LS, Matiasek K, Jäderlund KH, Zablotski Y, Gröndahl G. (2025). Motor pathway evaluation by transcranial magnetic stimulation in Swedish horses with acquired equine polyneuropathy. Equine Vet J. https://doi.org/10.1111/evj.14506

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

May, Anna
  • Equine Clinic, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University, Munich, Germany.
Hanche-Olsen, Siv
  • Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Ås, Norway.
Goehring, Lutz S
  • Gluck Equine Research Center, University of Kentucky, Lexington, Kentucky, USA.
Matiasek, Kaspar
  • Section of Clinical & Comparative Neuropathology, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University, Munich, Germany.
Jäderlund, Karin Hultin
  • Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Ås, Norway.
Zablotski, Yury
  • Clinic for Ruminants, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University, Munich, Germany.
Gröndahl, Gittan
  • Department of Animal Health and Antimicrobial Strategies, Swedish Veterinary Agency, Uppsala, Sweden.

Grant Funding

  • Swedish Association for the Protection of Animals (Svenska Djurskyddsfu00f6reningen)

References

This article includes 28 references
  1. Gröndahl G, Hanche‐Olsen S, Bröjer J, Ihler CF, Jäderlund KH, Egenvall A. Acquired equine polyneuropathy in Norway and Sweden: a clinical and epidemiological study.. Equine Vet J 2012;44(S43):36–44.
  2. Hanche‐Olsen S, Teige J, Skaar I, Ihler CF. Polyneuropathy associated with forage sources in Norwegian horses.. J Vet Intern Med 2008;22(1):178–184.
  3. Telama H, Alho J, Virtala A‐M, Tulamo R‐M. Acquired equine polyneuropathy – a review and an account of Finnish outbreaks.. Suomen Eläinlääkärilehti 2011;117(5):301–308.
  4. Wolff C, Egenvall A, Hanche‐Olsen S, Gröndahl G. Spatial and temporal distribution of incidence of acquired equine polyneuropathy in Norway and Sweden, 1995–2012.. BMC Vet Res 2014;10:265.
  5. Hahn CN, Matiasek K, Syrja P, Jokinen TS, MacIntyre N, Tulamo RM. Polyneuropathy of Finnish horses characterised by inflammatory demyelination and intracisternal Schwann cell inclusions.. Equine Vet J 2008;40(3):231–236.
  6. Gustafsson K, Roneus M. Outbreaks of neurological disorders in horses.. Svensk Veterinärtidning 2000;52:253–259.
  7. Hanche‐Olsen S, Kielland C, Ihler CF, Hultin JK. Long‐term follow‐up of Norwegian horses affected with acquired equine polyneuropathy.. Equine Vet J 2017;49(5):577–583.
  8. Hanche‐Olsen S, Matiasek K, Molin J, Rosati M, Hahn C, Hultin Jaderlund K. Acquired equine polyneuropathy of Nordic horses – a conspicuous inclusion body schwannopathy.. Neuromuscul Disord 2017;27(10):931–941.
  9. Hanche‐Olsen S. Acquired equine polyneuropathy – clinical, pathological and epidemiological aspects [Philosophiae Doctor].. Oslo, Norway: Norwegian University of Life Sciences; 2017.
  10. Tracy JA, Dyck PJB. The spectrum of diabetic neuropathies.. Phys Med Rehabil Clin N Am 2009;19(1):1.
  11. Griffin JW, Li CY, Ho TW, Tian M, Gao CY, Xue P. Pathology of the motor‐sensory axonal Guillain–Barre syndrome.. Ann Neurol 1996;39(1):17–28.
  12. Matsumoto H, Hanajima R, Terao Y, Ugawa Y. Magnetic‐motor‐root stimulation: review.. Clin Neurophysiol 2013;124:1055–1067.
  13. Schriefer TN, Mills KR, Murray NM, Hess CW. Evaluation of proximal facial nerve conduction by transcranial magnetic stimulation.. J Neurol Neurosurg Psychiatry 1988;51:60–66.
  14. Voitenkov VV, Klimkin A, Skripchenko N, Aksenova A. Transcranial magnetic stimulation as an additional diagnostic tool in children with acute inflammatory demyelinating polyneuropathy.. J Pediatr Neurosci 2017;12(2):144–148.
  15. Journée SL, Journée HL, Berends HI, Reed SM, de Bruijn CM, Delesalle CJG. Comparison of muscle MEPs from transcranial magnetic and electrical stimulation and appearance of reflexes in horses.. Front Neurosci 2020;14:570372.
    doi: 10.3389/fnins.2020.570372google scholar: lookup
  16. Rapisarda G, Bastings E, Maertens de Noordhout A, Pennisi G, Delwaide PJ. Can motor recovery in stroke patients be predicted by early transcranial magnetic stimulation?. Stroke 1996;27:2191–2196.
  17. McCombe PA, Pollard JD, McLeod JG. Chronic inflammatory demyelinating polyradiculoneuropathy. A clinical and electrophysiological study of 92 cases.. Brain 1987;110:1617–1630.
  18. Nollet H, Van Ham L, Deprez P, Vanderstraeten G. Transcranial magnetic stimulation: review of the technique, basic principles, and applications.. Vet J 2003;166(1):28–42.
  19. Nollet H, Van Ham L, Dewulf J, Vanderstraeten G, Deprez P. Standardization of transcranial magnetic stimulation in the horse.. Vet J 2003;166(3):244–250.
  20. Walendy L, Goehring LS, Zablotski Y, Weyh T, Matiasek K, May A. Evaluation and utility of submaximal stimulation intensity in transcranial magnetic stimulation in the standing horse.. J Equine Vet Sci 2022;112:103912.
  21. Nollet H, Deprez P, Van Ham L, Dewulf J, Decleir A, Vanderstraeten G. Transcranial magnetic stimulation: normal values of magnetic motor evoked potentials in 84 normal horses and influence of height, weight, age, and sex.. Equine Vet J 2004;36(1):51–57.
  22. Mayhew IGJ. Large animal neurology.. Ames, IA: Wiley‐Blackwell; 2009. p. 11–46.
  23. De Lahunta A, Glass E, Kent M. Veterinary neuroanatomy and clinical neurology.. 4th ed. Philadelphia, PA: Elsevier, Saunders; 2014.
  24. Coggeshall RE, Ito H. Sensory fibres in ventral roots L7 and S1 in the cat.. J Physiol 1977;267:215–235.
  25. Phillips LH, Park TS, Shaffrey ME, Shaffrey CL. Electrophysiological evidence for afferent nerve fibers in human ventral roots.. Muscle Nerve 2000;23:410–415.
  26. Rijckaert J, Pardon B, Saey V, Van Ham L, Ducatelle R, van Loon G. Determination of magnetic motor evoked potentials latency time cutoff values for detection of spinal cord dysfunction in horses.. J Vet Intern Med 2019;33(5):2312–2318.
  27. Varadarajan SG, Hunyara JL, Hamilton NR, Kolodkin AL, Huberman AD. Central nervous system regeneration.. Cell 2022;185(1):77–94.
  28. Journée SL, Journée HL, Bergmann W, Chantziaras I, Vanderperren K, Raes E. Evaluation of the diagnostic value of transcranial electrical stimulation (TES) to assess neuronal functional integrity in horses.. Front Neurosci 2024;11(18):1342803.

Citations

This article has been cited 1 times.
  1. Björnsdóttir S, Sigurðardóttir ÓG, Oddsdóttir C, Reynisdóttir I, Hanche-Olsen S, Gröndahl G. Outbreak of digital extensor dysfunction compatible with acquired equine polyneuropathy observed for the first time in Iceland. Acta Vet Scand 2025 Nov 26;67(1):50.
    doi: 10.1186/s13028-025-00835-4pubmed: 41299546google scholar: lookup
Subscribe to our newsletter
Join 99,780 horse owners like you who receive our email updates on horse health and nutrition.