Page 1372 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

The foal 1347

VetBooks.ir 14.13 14.14

Fig. 14.13 The use of squeeze-induced somnolence Fig. 14.14 A foal with atresia ani.
to treat a foal with clinical signs of NMS.

interact with the environment and finally suck from condition may be due to vascular anomalies in the
the mare takes considerable patience, time and skill. fetus. Defects are most commonly found between
the left ventral and dorsal colon. Atresia ani is asso-
Prognosis ciated with the absence of an anus and variable parts
The prognosis for foals with NMS is usually very of the rectum. Concurrent urinary tract defects may
good with appropriate supportive care. Reported be present (rare).
survival rates range widely but can be as high as
80–90%. The prognosis for foals that experience Clinical presentation
significant severe hypoxic injury is generally poorer. Foals are normal at birth and usually stand and suck
Signs of uncontrollable seizures, anuric renal failure normally. They usually present within 4–24 hours
and severe cardiovascular dysfunction are generally with a progressive moderate to severe colic, due to
associated with a poor prognosis. physical obstruction of the passage of gas and faeces.
The more caudal the defect in the gut, the slower
ATRESIA COLI/RECTI/ANI the onset of signs. In atresia ani, no anus is observed,
or it appears grossly abnormal. In obstructions else-
Definition/overview where, digital examination p/r reveals no faeces pres-
Atresia coli, atresia recti and atresia ani are rare con- ent or palpable. Abdominal distension, anorexia and
genital abnormalities where part of the hindgut fails to colic develop and progress over a period of hours.
develop in utero. Obstruction of the passage of faeces
leads to clinical signs of colic, usually manifest in the Differential diagnosis
first 1–2 days of life. In most cases the condition is fatal. Meconium retention; abdominal crisis (e.g. small
intestinal volvulus); ruptured bladder; ileocolonic
Aetiology/pathophysiology aganglionosis (lethal white syndrome); ileus.
These are developmental abnormalities of one or
more segments of the GI tract. Atresia coli and, to Diagnosis
a lesser extent, atresia ani are the most commonly Diagnosis is based on clinical signs, physical and dig-
seen (Fig. 14.14). Atresia coli is characterised by ital examination, which is diagnostic for atresia ani,
membranous occlusion of the lumen, remnants of and diagnostic imaging. Ultrasound examination may
gut connecting two blind ends (cord atresia) or the confirm colonic obstruction or possible narrowing.
presence of blind ends with no connection. The Plain radiographs of the abdomen may demonstrate