Nonstrangulating intestinal infarctions associated with Strongylus
vulgaris: Clinical presentation and treatment outcomes of 30
T. H. PIHL
* , M. K. NIELSEN
, S. N. OLSEN
, P. S. LEIFSSON
and S. JACOBSEN
Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Denmark
M. H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, USA
Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark.
*Correspondence email: email@example.com; Received: 06.12.16; Accepted: 29.10.17
Background: Strongylus vulgaris is re-emerging in horses kept under surveillance-based parasite control regimens. Information on nonstrangulating
intestinal infarction associated with S. vulgaris is needed to improve recognition of the condition.
Objective: To describe the typical clinical presentation, laboratory ﬁndings, gross pathology, treatment and outcome of horses with nonstrangulating
Study design: Retrospective case series.
Methods: Nonstrangluating intestinal infarction was diagnosed in 30 horses with a localised intestinal infarction with concurrent signs of S. vulgaris
migration and no signs of intestinal strangulation or enterocolitis. Data were obtained from medical records in the period 2008–2016. Long-term follow-
up information was obtained by telephonic interviews. Levels of S. vulgaris-speciﬁc antibodies were retrospectively assessed. Associations between
nonstrangulating intestinal infarction and selected variables were evaluated using Fisher
s exact and Mann–Whitney U tests.
Results: The most consistent ﬁndings at admission were mild colic of >24 h duration without signs of shock or strangulated intestine, increased
peritoneal ﬂuid WBC (>5 9 10
/L), increased serum amyloid A (SAA) concentration and a positive S. vulgaris-speciﬁc antibody titre. Medical treatment
was attempted in nine horses with none surviving. Exploratory laparotomy was performed in 21 horses. Eleven horses were subjected to euthanasia
intraoperatively due to the presumed poor prognosis. Of the nine horses, three (33%) undergoing intestinal resection survived to discharge. The
surviving horses were alive and returned to athletic function for at least 2 years following discharge.
Main limitations: Only nine of the 30 horses underwent resection of the infarcted intestine, and the prognosis for surgical intervention in
nonstrangulating intestinal infarction is, therefore, difﬁcult to estimate.
Conclusions: In areas where S. vulgaris is prevalent, nonstrangulating intestinal infarction should be considered as a differential diagnosis in horses
presenting with mild colic and peritonitis. Survival of nonstrangulating intestinal infarction is possible in cases where surgical intervention with resection
of the infarcted intestine is feasible.
The summary is available in Spanish – see Supporting Information.
Keywords: horse; colic; large strongyle; thromboembolic
Nonstrangulating intestinal infarction in horses is associated with migration
of the larval stages of the helminth Strongylus vulgaris [1–5]. Infarctions
may occur in segments of the intestinal wall when arteries or arterioles are
occluded by thrombi produced as a consequence of larval migration in the
main branches of the cranial mesenteric artery [1,2,4,6].
Descriptions of clinical and laboratory ﬁndings in horses presented with
nonstrangulating intestinal infarction are mainly derived from older case
series [2,7,8] or studies using experimental inoculation [1,4,6,9].
Information on how these cases present today in modern equine practice
is lacking. Gerber et al.  described nonstrangulating intestinal infarction
as colic with an initial phase of acute and violent pain followed by a quiet
phase which could last for several days, followed by endotoxaemia, shock
and death. More recently, a similar presentation was described in a pony
with verminous arteritis . Other studies have described varying degrees
of abdominal pain at admission with no consistent laboratory ﬁndings [2,7].
Larger studies of colic and peritonitis in horses have, however, described
pyrexia, peritonitis and palpation per rectum of a painful and thickened
mesenteric root in horses with S. vulgaris-associated colic [11–13].
Experimental infections of parasite-na
ıve foals with high doses of infective
larvae [1,4,14] have resulted in signs of severe colic and a fatal outcome.
On post-mortem examination, nonstrangulating intestinal infarction of the
small and large intestine was described as clearly demarcated areas that
were black to red in colour and raised above the level of the healthy
intestine. Fibrin deposits on the sites of infarction and peritonitis were also
The surveillance-based parasite control strategies, so called selective
therapy, implemented in several European countries since 1999 as a
consequence of the prescription-only anthelmintic policy have been
associated with an increased prevalence of S. vulgaris [18,19]. Recently, a
Danish study showed signiﬁcantly increased concentrations of S. vulgaris-
speciﬁc antibodies in horses diagnosed with nonstrangulating intestinal
infarction compared with a group of matched controls . Thus,
S. vulgaris is endemic in the Danish equine population and has the
potential to cause severe disease. As similar situations might occur in
other countries, where restrictions of anthelmintic usage are being
adopted, it is pertinent to maintain focus on the pathological potential of
this parasite, the clinical presentation and laboratory ﬁndings of
nonstrangulating intestinal infarction, and to stay updated about
diagnostic methods and treatment options at hand. The aim of this study
was thus to describe the clinical presentation, laboratory ﬁndings,
treatment and outcome of 30 cases diagnosed with nonstrangulating
intestinal infarction during 2008–2016.
Materials and methods
All data and samples from client-owned horses were collected with the
owner’s consent as part of the routine diagnostic evaluation.
Equine Veterinary Journal 50 (2018) 474–480 © 2017 EVJ Ltd
Equine Veterinary Journal ISSN 0425-1644