Page 842 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 817

VetBooks.ir of rotavirus diarrhoea. Rotavirus can persist in the Large volumes of gastric reflux may be produced.
Following decompression of the stomach, horses
environment for several months.
Prognosis will often appear more depressed than painful, as
opposed to when a strangulating small-intestinal
The prognosis is very good to excellent if adequate lesion is present. Tachycardia is common and can be
supportive care can be provided. Complications are marked (80–120 bpm). Varying degrees of dehydra-
uncommon. tion, fever and toxaemia may be present. The appear-
ance of the gastric reflux is variable: a reddish colour
DUODENITIS/PROXIMAL JEJUNITIS and a foetid odour may suggest enteritis, but these
are not consistent. Laminitis is a common complica-
Definition/overview tion, occurring in up to 30% of cases.
Also termed anterior enteritis or proximal enteritis,
duodenitis/proximal jejunitis (DPJ) is an inflamma- Differential diagnosis
tory condition of the small intestine that results in The main differential diagnoses early in disease are
fluid distension of the small intestine, gastric reflux, strangulating and non-strangulating obstructive
toxaemia, colic and depression. While DPJ has been small-intestinal lesions. Less commonly, primary
reported in most regions of the USA, there is anec- ileus can produce the same clinical signs. One of the
dotal evidence that the prevalence of disease may greatest initial diagnostic challenges in these cases is
be greater in southern states. Most cases occur in determining whether a surgical or a medical lesion
the summer months; however, the reason for this is present.
is unclear. The vast majority of cases are in horses
more than 2 years old. Diagnosis
Multiple loops of distended small intestine are usu-
Aetiology/pathophysiology ally palpable p/r. Ultrasonographic examination of
The aetiology is unknown; however, an infectious the abdomen typically displays multiple loops of dis-
cause is highly suspected. Recent evidence has tended small intestine. In general, intestinal loops
implicated Clostridium difficile. Lesions tend to be are more motile than strangulating lesions; however,
restricted to the duodenum and proximal jejunum. this is not always the case. Abdominocentesis can
Inflammation of the affected areas of small intestine be useful in some cases. Abdominal fluid may have
results in increased net movement of fluid into the a high total protein (>30 g/l [3 g/dl]) with normal
lumen. While intestinal motility may be present, cell count (<5 × 10 cells/l), but results are variable.
9
motility may not be coordinated and progressive, Abdominal fluid changes are typically not as severe
and small-intestinal distension develops. Ileus may as with strangulating lesions.
occur as a result of intestinal distension, electrolyte Surgical exploration is the only definitive diag-
disturbances, toxaemia or pain. As fluid accumu- nostic test and should be considered when there is
lates in the small intestine, signs of colic develop. a reasonable suspicion of a strangulating lesion.
Eventually, gastric distension may occur. Gastric Differentiation of DPJ from a strangulating small-
distension typically causes the most severe signs of intestinal lesion is critical; however, it is not always
colic, and gastric rupture may occur if the stomach possible. Certain clinical findings, including fever,
is not decompressed. depression following gastric decompression, hyper-
motility of intestinal loops on ultrasonographic
Clinical presentation examination and an increased abdominal fluid total
Acute onset of colic is the most common presen- protein with a normal cell count, suggest DPJ.
tation. Occasionally, depression and fever may be
noted before colic signs develop. Colic signs are Management
largely attributable to gastric distension. Horses can Initial goals should be stabilisation of the patient and
be in great pain if the stomach is markedly distended. deciding whether surgical exploration is required.