Page 867 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

842 CHAPTER 4

VetBooks.ir Diagnosis of questionable benefit. A discussion of management
practices with the owner is important.
A history of exposure to sand, or sandy soils, and
clinical signs should raise the clinical index of sus-
picion. Although commonly recommended, faecal Prognosis
sand content evaluation by letting a suspension of Overall, the prognosis is excellent. In a small pro-
faeces and water settle out in a rectal sleeve is not portion of cases, severe colon irritation may result
recommended as the quantity of sand in the faeces in chronic diarrhoea and ill-thrift. Management
correlates poorly with large colon accumulation. changes may be required to prevent further cases.
Palpation p/r is unremarkable unless there is a con-
current large colon impaction. Sand accumulation RIGHT DORSAL COLITIS
may be evident radiographically (Fig. 4.166) or
ultrasonographically, particularly in the cranioven- Definition/overview
tral abdomen. Haematology should be unremark- Right dorsal colitis is an uncommon syndrome char-
able, apart from changes consistent with the degree acterised by ulcerative inflammation of the right
of dehydration, although mild neutropenia is occa- dorsal colon.
sionally present. Total protein levels do not tend to
decrease as is usually observed with enterocolitis. Aetiology/pathophysiology
Peritoneal fluid is usually unremarkable. Chronic or excessive administration of NSAIDs is
the most common risk factor; however, a history
Management of NSAID use is not always present. Concurrent
Enteral fluid therapy is useful in mild cases. Psyllium dehydration or hypotension increases the risk.
(1.0 g/kg) combined with magnesium sulphate (1.0 g/ Phenylbutazone use is most commonly reported, but
kg) daily via NG tube has been shown to be effec- it is unclear whether this drug is of higher risk or
tive in the removal of sand accumulations. Treatment whether it is used more often. Performance horses
is continued for 3–5 days followed by repeat radio- are most commonly affected because of the heavy
graphic or ultrasonographic examination. Following use of NSAIDs in this group.
resolution, periodic evaluation (every 3–6 months) via NSAID administration results in decreased pros-
abdominal radiography or ultrasonography should be taglandin levels and prostaglandins are involved in
considered, particularly if management changes are local protection in the colon. With NSAID use,
not feasible. particularly at high levels and for prolonged periods
Intermittent administration of psyllium may of time, or with concurrent dehydration or hypo-
help reduce sand accumulation, but the response is tension, mucosal inflammation and ulceration may
highly variable between individuals. Administration develop if local protective effects are overwhelmed.
of 0.25 kg of psyllium/500 kg once daily for 7 days, The inflammatory response that is generated fur-
performed monthly, has been recommended but is ther damages the intestinal mucosa. Clinical signs
can result from intestinal inflammation, damage to
the mucosal barrier with subsequent absorption of
4.166 bacterial toxins and exudation of plasma proteins.

Clinical presentation
Two general syndromes are observed. In the acute
form, colic is the predominant clinical sign and is
often accompanied by fever, depression, lethargy
and signs of endotoxaemia. Diarrhoea may also be
Fig. 4.166 Radiograph demonstrating sand present. In the chronic form, weakness, weight loss,
accumulation in the ventral abdomen. (Photo courtesy depression, lethargy, intermittent colic and peripheral
K Niinistö) oedema may be observed. Diarrhoea is less common.