FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Equine veterinary journal2026; doi: 10.1002/evj.70208

Parascaris spp. induced surgical colic in juvenile horses-A Scandinavian perspective.

Abstract: Parascaris spp. commonly infects foals, and high burdens can cause fatal small intestinal impactions. Progressive anthelmintic resistance poses a risk for an increase of Parascaris spp. related disease in juvenile horses. Objective: To investigate Parascaris-related surgical intestinal lesions, with special emphasis on ascarid impactions, in Scandinavia by exploring (1) disease occurrence and (2) short-term survival rates after laparotomy in affected foals and yearlings. Methods: Restrospective case series. Methods: A retrospective clinical record search was conducted at six Scandinavian equine hospitals during a 7-15-year period. Horses older than 1 month but less than 2 years of age that had been surgically treated for colic were included. Age, breed, surgical diagnosis, presence of Parascaris spp. infection, immediate anthelmintic history and short-term survival, defined as survival to hospital discharge, were recorded. Results: A total of 233 records were included and lesions involving the small intestine were observed in 52.8% (123/233). Fourteen foals were diagnosed with ascarid impaction at laparotomy, with an occurrence of 6.0% (14/233), encompassing 11.4% of surgical small intestinal lesions (14/123) and 9.7% of horses younger than 1 year of age (13/134). Six foals with ascarid impaction had been treated with an anthelmintic drug within 2 days of presentation. Four foals with ascarid impaction survived to discharge. Overall occurrence of Parascaris-associated intestinal lesions, including impactions, was 13.7% (32/233), encompassing 26.0% (32/123) of all small intestinal abnormalities, and with a short-term survival rate of 38% (12/32). Conclusions: Retrospective study design, hospital-dependent variations could not be controlled. No previous data to compare disease occurrence. Conclusions: Parascaris spp. related disease in juvenile horses comprises a substantial portion of small intestinal surgical lesions with a poor prognosis for survival. With the appearance of multi-drug-resistant parasite populations, it is important to develop management practices to reduce parasite infection burdens.
© 2026 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
Get Full Text
Publication Date: 2026-06-16 PubMed ID: 42304599DOI: 10.1002/evj.70208Google 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.

Overview

  • This study examined cases of intestinal disease caused by Parascaris spp. infections in foals and yearlings undergoing colic surgery in Scandinavian equine hospitals.
  • The research focused on how common these infections are in surgical cases and the short-term survival outcomes after surgery.

Background

  • Parascaris spp. are parasitic roundworms frequently infecting young horses such as foals.
  • In severe cases, heavy worm burdens can cause intestinal impactions requiring surgical intervention.
  • There is growing concern due to increasing anthelmintic resistance, meaning these parasites are becoming harder to control with standard deworming drugs, potentially leading to more frequent or severe infections.

Objectives

  • To investigate the occurrence of Parascaris-related surgical intestinal lesions in Scandinavian juvenile horses.
  • To assess the short-term survival rates of affected animals post-surgery (specifically up to hospital discharge).

Methods

  • A retrospective review was conducted, analyzing clinical cases over a 7 to 15-year period from six different equine hospitals in Scandinavia.
  • Inclusion criteria:
    • Horses aged from just over 1 month up to 2 years.
    • Horses that had undergone surgery for colic.
  • Data collected included age, breed, surgical diagnosis, presence of Parascaris infection, recent deworming history, and survival to hospital discharge.

Results

  • 233 surgical cases of juvenile horses with colic were reviewed.
  • More than half (52.8%, 123/233) had lesions involving the small intestine.
  • Parascaris-related intestinal lesions were identified in 32 horses (13.7% of all cases), including:
    • 14 cases (6.0% of all cases) had ascarid impactions, which accounted for 11.4% of all small intestinal lesions.
    • Among horses younger than 1 year, 9.7% had ascarid impactions.
  • Interestingly, six of the foals with ascarid impactions had received anthelmintic treatment within two days before hospital admission, indicating treatment failure or resistance.
  • The overall short-term survival (to hospital discharge) for horses with Parascaris-associated intestinal lesions was poor at 38% (12/32).
  • Four of the foals with ascarid impaction survived to discharge, emphasizing the severity and generally poor prognosis in these cases.

Conclusions

  • Parascaris spp. infections contribute significantly to small intestinal surgical lesions in juvenile horses in Scandinavia.
  • The prognosis for survival following such infections complicated by intestinal impactions is generally poor.
  • The presence of multi-drug resistant Parascaris populations reinforces the need to develop improved parasite management strategies beyond standard anthelmintic treatments.
  • The study was limited by:
    • Its retrospective nature, making it reliant on existing clinical records.
    • Variability across hospitals which could not be controlled.
    • Lack of previous comparable data on disease occurrence in this specific region and age group.
  • Overall, the research highlights an important and emerging challenge in equine veterinary medicine related to parasite control and surgical outcomes in young horses.

Cite This Article

APA
Tydén E, Risnes Hellings I, Toft Nielsen K, Bergren A, Holmgren I, Attin S, Pihl T, Kendall A, Hedberg Alm Y. (2026). Parascaris spp. induced surgical colic in juvenile horses-A Scandinavian perspective. Equine Vet J. https://doi.org/10.1002/evj.70208

Publication

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

Researcher Affiliations

Tydén, E
  • Department of Animal Biosciences, Swedish University of Agriculture, Uppsala, Sweden.
Risnes Hellings, I
  • Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Ås, Norway.
Toft Nielsen, K
  • Department of Veterinary Clinical Sciences, University of Copenhagen, Denmark.
Bergren, A
  • Bjerke Dyrehospital, Oslo, Norway.
Holmgren, I
  • Mälaren Equine Clinic, Sigtuna, Sweden.
Attin, S
  • Evidensia Equine Hospital, Helsingborg, Sweden.
Pihl, T
  • Department of Veterinary Clinical Sciences, University of Copenhagen, Denmark.
Kendall, A
  • Mälaren Equine Clinic, Sigtuna, Sweden.
Hedberg Alm, Y
  • Department of Animal Biosciences, Swedish University of Agriculture, Uppsala, Sweden.

Grant Funding

  • H-22-47-712 / The Swedish-Norwegian Foundation for Equine Research

References

This article includes 40 references
  1. Laugier C, Sevin C, Ménard S, Maillard K. Prevalence of infection in foals on French stud farms and first report of ivermectin‐resistant populations in France.. Vet Parasitol 2012;188(1–2):185–189.
    doi: 10.1016/j.vetpar.2012.02.022google scholar: lookup
  2. Armstrong SK, Woodgate RG, Gough S, Heller J, Sangster NC, Hughes KJ. The efficacy of ivermectin, pyrantel and fenbendazole against infection in foals on farms in Australia.. Vet Parasitol 2014;205(3–4):575–580.
    doi: 10.1016/j.vetpar.2014.08.028google scholar: lookup
  3. Relf VE, Lester HE, Morgan ER, Hodgkinson JE, Matthews JB. Anthelmintic efficacy on UK thoroughbred stud farms.. Int J Parasitol 2014;44(8):507–514.
    doi: 10.1016/j.ijpara.2014.03.006google scholar: lookup
  4. Alanazi AD, Mukbel RM, Alyousif MS, AlShehri ZS, Alanazi IO, Al‐Mohammed HI. A field study on the anthelmintic resistance of spp. in Arab foals in the Riyadh region, Saudi Arabia.. Vet Q 2017;37(1):200–205.
    doi: 10.1080/01652176.2017.1334981google scholar: lookup
  5. Lind EO, Christensson D. Anthelmintic efficacy on Parascaris equorum in foals on Swedish studs.. Acta Vet Scand 2009;51:45.
    doi: 10.1186/1751-0147-51-45google scholar: lookup
  6. Hautala K, Nareaho A, Kauppinen O, Nielsen MK, Sukura A, Rajala‐Schultz PJ. Risk factors for equine intestinal parasite infections and reduced efficacy of pyrantel embonate against Parascaris spp.. Vet Parasitol 2019;273:52–59.
    doi: 10.1016/j.vetpar.2019.08.004google scholar: lookup
  7. Clayton HM, Duncan JL. Development of immunity to Parascaris‐Equorum infection in the foal.. Res Vet Sci 1979;26(3):383–384.
    doi: 10.1016/s0034-5288(18)32899-6google scholar: lookup
  8. Clayton HM, Duncan JL. Clinical signs associated with Parascaris‐equorum infection in worm‐free pony foals and yearlings.. Vet Parasitol 1978;4(1):69–78.
    doi: 10.1016/0304-4017(78)90037-7google scholar: lookup
  9. Cribb NC, Cote NM, Boure LP, Peregrine AS. Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985‐2004).. N Z Vet J 2006;54(6):338–343.
    doi: 10.1080/00480169.2006.36721google scholar: lookup
  10. Southwood LL, Baxter GM, Bennett DG, Ragle CA. Ascarid impaction in young horses.. Comp Cont Educ Pract Vet 1998;20(1):100–106.
  11. Alm YH, Tydén E, Riihimäki M, Anlén K, Nyman S, Hedenby J. Hästens mag‐tarmparasiter—Att förebygga och behandla (in Swedish). [The horse's gastrointestinal parasites—to prevent and treat] [Folder].. 2022.
  12. Pyatt A, Stratford C, Perrett J, Austin C, Rendle D, Gilby DE. The CANTER Guidelines—for sustainable parasite control.. 2024.
  13. Nielsen MK, Mittel L, Grice A, Erskine M, Graves E, Vaala W. AAEP Parasite Control Guidelines.. American Association of Equine Practitioners 2019.
  14. . A Guide to the Treatment and Control of Equine Gastrointestinal Parasite Infections. Second Edition.. European Scientific Counsel Companion Animal Parasites (ESCCAP) 2019.
  15. Lyons ET, Tolliver SC, Ionita M, Collins SS. Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate in horse foals with emphasis on ascarids (Parascaris equorum) in field studies on five farms in Central Kentucky in 2007.. Parasitol Res 2008;103(2):287–291.
    doi: 10.1007/s00436-008-0966-8google scholar: lookup
  16. Martin F, Hoglund J, Bergstrom TF, Karlsson Lindsjo O, Tyden E. Resistance to pyrantel embonate and efficacy of fenbendazole in Parascaris univalens on Swedish stud farms. Vet Parasitol 2018;264:69–73.
    doi: 10.1016/j.vetpar.2018.11.003google scholar: lookup
  17. Martin F, Halvarsson P, Alm YH, Tyden E. Occurrence of fenbendazole resistance in Parascaris spp. on breeding farms in Sweden. Vet Parasitol 2024;331:110272.
    doi: 10.1016/j.vetpar.2024.110272google scholar: lookup
  18. Schougaard H, Nielsen MK. Apparent ivermectin resistance of Parascaris equorum in foals in Denmark. Vet Rec 2007;160(13):439–440.
    doi: 10.1136/vr.160.13.439google scholar: lookup
  19. Sallé G, Guillot J, Tapprest J, Foucher N, Sevin C, Laugier C. Compilation of 29 years of postmortem examinations identifies major shifts in equine parasite prevalence from 2000 onwards. Int J Parasitol 2019;50(2):125–132.
    doi: 10.1016/j.ijpara.2019.11.004google scholar: lookup
  20. Tydén E, Dahlberg J, Karlberg O, Höglund J. Deep amplicon sequencing of preselected isolates of in β‐tubulin codons associated with benzimidazole resistance in other nematodes. Parasit Vectors 2014;7:410.
    doi: 10.1186/1756-3305-7-410google scholar: lookup
  21. Martin F, Halvarsson P, Delhomme N, Höglund J, Tydén E. Exploring the β‐tubulin gene family in a benzimidazole‐resistant population. Int J Parasitol Drugs Drug Resist 2021;17:84–91.
    doi: 10.1016/j.ijpddr.2021.08.004google scholar: lookup
  22. Boersema JH, Eysker M, Maas J, van der Aar WM. Comparison of the reappearance of strongyle eggs on foals, yearlings and adult horses after treatment with ivermectin or pyrantel. Vet Q 1996;18(9):7–9.
    doi: 10.1080/01652176.1996.9694602google scholar: lookup
  23. Craig TM, Diamond PL, Ferwerda NS, Thompson JA. Evidence of ivermectin resistance by on a Texas horse farm. J Equine Vet Sci 2007;27(2):67–71.
    doi: 10.1016/j.jevs.2006.12.002google scholar: lookup
  24. Tatz AJ, Segev G, Steinman A, Berlin D, Milgram J, Kelmer G. Surgical treatment for acute small intestinal obstruction caused by infection in 15 horses (2002‐2011). Equine Vet J 2007;2012:111–114.
    doi: 10.1111/j.2042-3306.2012.00607.xgoogle scholar: lookup
  25. Santschi EM, Slone DE, Embertson RM, Clayton MK, Markel MD. Colic surgery in 206 juvenile thoroughbreds: survival and racing results. Equine Vet J 2000;32(S32):32–36.
    doi: 10.1111/j.2042-3306.2000.tb05331.xgoogle scholar: lookup
  26. Cable CS, Fubini SL, Erb HN, Hakes JE. Abdominal surgery in foals: a review of 119 cases (1977‐1994). Equine Vet J 1997;29(4):257–261.
    doi: 10.1111/j.2042-3306.1997.tb03120.xgoogle scholar: lookup
  27. Vatistas NJ, Snyder JR, Wilson WD, Drake C, Hildebrand S. Surgical treatment for colic in the foal (67 cases): 1980‐1992. Equine Vet J 1996;28(2):139–145.
    doi: 10.1111/j.2042-3306.1996.tb01606.xgoogle scholar: lookup
  28. Adams R, Koterba AM, Brown MP, Cudd TC, Baker WA. Exploratory celiotomy for gastrointestinal disease in neonatal foals: a review of 20 cases. Equine Vet J 1998;20(1):9–12.
    doi: 10.1111/j.2042-3306.1988.tb01442.xgoogle scholar: lookup
  29. MacKinnon MC, Southwood LL, Burke MJ, Palmer JE. Colic in equine neonates: 137 cases (2000‐2010). J Am Vet Med Assoc 2013;243(11):1586–1595.
    doi: 10.2460/javma.243.11.1586google scholar: lookup
  30. van Loon J, Visser EMS, de Mik‐van Mourik M, Kerbert P, Huppes T, Menke ES. Colic surgery in horses: a retrospective study into short‐ and long‐term survival rate, complications and rehabilitation toward sporting activity. J Equine Vet Sci 2020;90:103012.
    doi: 10.1016/j.jevs.2020.103012google scholar: lookup
  31. Clayton HM, Duncan JL, Dargie JD. Pathophysiological changes associated with Parascaris equorum infection in the foal.. Equine Vet J 1980;12(1):23–25.
    doi: 10.1111/j.2042-3306.1980.tb02292.xgoogle scholar: lookup
  32. Alm YH, Tydén E, Martin F, Lerna J, Halvarsson P. Farm size and biosecurity measures associated with Strongylus vulgaris infection in horses.. Equine Vet J 2025;57(3):703–711.
    doi: 10.1111/evj.14212google scholar: lookup
  33. Joó K, Trúzsi RL, Lengyel DA, Jakab S. Evaluation of risk factors affecting strongylid egg shedding on Hungarian and Transylvanian horse farms.. Magy Allatorv Lap 2022;144(1):31–44.
    doi: 10.1016/j.vprsr.2021.100663google scholar: lookup
  34. Tzelos T, Morgan ER, Easton S, Hodgkinson JE, Matthews JB. A survey of the level of horse owner uptake of evidence‐based anthelmintic treatment protocols for equine helminth control in the UK.. Vet Parasitol 2019;274:108926.
    doi: 10.1016/j.vetpar.2019.108926google scholar: lookup
  35. Dauparaitė E, Kupčinskas T, Hoglund J, Petkevičius S. A survey of control strategies for equine small strongyles in Lithuania.. Helminthologia 2021;58(3):225–232.
    doi: 10.2478/helm-2021-0031google scholar: lookup
  36. Elghryani N, Duggan V, Relf V, de Waal T. Questionnaire survey on helminth control practices in horse farms in Ireland.. Parasitology 2019;146(7):873–882.
    doi: 10.1017/s0031182019000271google scholar: lookup
  37. Lindgren K, Ljungvall Ö, Nilsson O, Ljungström BL, Lindahl C, Höglund J. Parascaris equorum in foals and in their environment on a Swedish stud farm, with notes on treatment failure of ivermectin.. Vet Parasitol 2008;151(2–4):337–343.
    doi: 10.1016/j.vetpar.2007.10.014google scholar: lookup
  38. DiPietro JA, Hutchens DE, Lock TF, Walker K, Paul AJ, Shipley C. Clinical trial of moxidectin oral gel in horses.. Vet Parasitol 1997;72(2):167–177.
    doi: 10.1016/s0304-4017(97)01108-4google scholar: lookup
  39. Ihler KF. Kontroll av innvolls parasitter hos hest (in Norwegian). [Control of gastrointestinal parasites in the horse].. NVT 2017;6:366–367.
  40. . Viden om hestens indvoldsorm (in Danish). [Knowledge about horse intestinal worms] [Folder].. Den Danske Dyrlægeforening 2024. 1–9.

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 106,596 horse owners like you who receive our email updates on horse health and nutrition.