Objective—To compare plasma endothelin (ET)- like
immunoreactivity between healthy horses and those
with naturally acquired gastrointestinal tract disorders.
Animals—29 healthy horses and 142 horses with
gastrointestinal tract disorders.
Procedure—Blood samples were collected from
healthy horses and from horses with gastrointestinal
tract disorders prior to treatment. Magnitude and
duration of abnormal clinical signs were recorded, and
clinical variables were assessed via thorough physical
examinations. Plasma concentrations of ET-like
immunoreactivity were measured by use of a radioimmunoassay
for human endothelin-1, and CBC and
plasma biochemical analyses were performed.
Results—Plasma ET-like immunoreactivity concentration
was significantly increased in horses with gastrointestinal
tract disorders, compared with healthy
horses. Median plasma concentration of ET-like
immunoreactivity was 1.80 pg/ml (range, 1.09 to 3.2
pg/ml) in healthy horses. Plasma ET-like immunoreactivity
was greatest in horses with strangulating largeintestinal
obstruction (median, 10.02 pg/ml; range, 3.8
to 22.62 pg/ml), peritonitis (9.19 pg/ml; 7.89 to 25.83
pg/ml), and enterocolitis (8.89 pg/ml; 6.30 to 18.36
pg/ml). Concentration of ET-like immunoreactivity was
significantly associated with survival, PCV, and duration
of signs of pain. However, correlations for associations
with PCV and duration of pain were low.
Conclusions and Clinical Relevance—Horses with
gastrointestinal tract disorders have increased plasma
concentrations of ET-like immunoreactivity, compared
with healthy horses. The greatest values were detected
in horses with large-intestinal strangulating
obstructions, peritonitis, and enterocolitis. This suggests
a potential involvement of ET in the pathogenesis
of certain gastrointestinal tract disorders in horses.
(Am J Vet Res 2002;63:454–458)