EQUINE | Proceedings
instestinal surgery in horses. To an aggressive surgeon,
any single indicator of intestinal strangulation makes a
horse with colic a surgical candidate until proven other-
wise. Conservative surgeons in the same situation prefer
to wait until one or two additional physical parameters
of strangulation support the initial assessment of intes-
tinal hypoperfusion before committing to laparotomy.
The exact effect of a brief delay in decision making, long
enough to allow early signs of impending cardiovascu-
lar shock to develop and support the choice for surgical
intervention, is hard to quantify but certainly helps the
decision-making process.
Contraindications for surgical intervention are mostly
clinical parameters indicative of enteritis. These include
the absence of pain, the presence of depression, fever (>
102.5 F), neutrophilia or neutropenia and the presence
of progressive intestinal sounds on auscultation. The
absence of pain must however be interpreted with cau-
tion. This is particularly true in cases of small intestinal
obstruction where horses with bowel incarceration in
internal hernias (in particular epiploic foramen entrap-
ment and strangulating lipomas) can appear normal for
a period of time after the initial episode of colic, until
intestinal distension occurs oral to the obstruction and
later become pain-free again when the bowel becomes
necrotic and the horse becomes depressed due to en-
dotoxaemia.
In recent years, abdominal ultrasonography in particu-
lar has proved complementary to the established clini-
cal examination in evaluating bowel for distension, mu-
ral thickness and motility. It has been mainly helpful in
identifying small intestinal obstruction and was found
to be more accurate than rectal palpation with a sen-
sitivity of 98% and a specificity of 84% for small intes-
tinal strangulating obstructions compared to 50% and
98% respectively for rectal examination (Klohnen et al.
1996). Ultrasonography from a ventral transabdominal
window was also helpful in detecting increased large
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colon wall thickness in horses with large colon torsion
with a sensitivity of 67% and a specificity of 98% (Pease
et al. 2004). Ultrasonography has further been reliable
for the identification of nephrosplenic entrapment of
the large colon, acquired inguinal or scrotal hernias and
sand accumulations in the large colon. Current practice
suggests that a technique referred to as FLASH (fast
localized abdominal sonography of horses), a 7-site,
10-minute transabdominal ultrasound protocol for
evaluation of the acute abdomen can be used by vet-
erinarians without extensive ultrasound experience to
detect major intra-abdominal abnormalities in horses
with colic. Busoni et al (2011) showed that FLASH was
able to show free abdominal fluid and abnormal intes-
tinal loops. The positive and negative predictive values
of the need for surgery of dilated turgid small intestinal
loops using FLASH were 89% and 81%, respectively.
Recent attention to blood plasma and peritoneal fluid
lactate levels have indicated that these parameters can
be used as prognostic indicators in horses with colic.
One study established the BPL reference range as 0.59
+ 0.22 mM and the PFL reference range as 0.49 + 0.27
mM. With each 1 mM increase in BPL or PFL, the respec-
tive odds ratios for required abdominal surgery increase
to 1.23 (BPL) and 1.58 (PFL), odds ratios for a required
intestinal resection increase to 1.20 (BPL) and 1.41 (PFL),
and odds ratios for developing ileus increase by 1.33
(BPL) and 1.36 (PFL). PFL concentrations of 1, 6, 12, and
16 mM corresponded to a probability of death of 11, 29,
63, and 82%, respectively, in horses without strangulat-
ing obstruction and of 25, 52, 82, and 92%, respectively,
in horses with strangulating obstruction (Delesalle et al.
2007).
The physical examination should be as complete as pos-
sible before administration of any diagnostic/therapeu-
tic analgesic medication is considered. Important clini-
cal signs may be masked by analgesic medication, the
degree of which depends on the particular drug’s po-
• Equine Health Update •