Page 1380 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

The foal 1355

VetBooks.ir latter being a rare complication. Incarcerated bowel Aetiology/pathophysiology
The pathophysiology of all presentations of uro-
leads to colic, local swelling and palpable pain.
Differential diagnosis peritoneum is still not completely understood, but a
number of risk factors and clinical scenarios (congen-
Umbilical infection or abscess; ventral abdominal ital and acquired) are well-recognised. Many cases
wall injuries; ventral oedema; colic. of bladder rupture in otherwise healthy neonates are
thought to occur during parturition, with defects
Diagnosis most commonly found in the dorsal wall, suggest-
In the majority of cases, palpation will determine the ing a predisposing congenital weakness. This pre-
size of the umbilical defect and its contents, give an sentation was initially reported more commonly in
indication as to whether it is reducible and rule out colts (suspected to be due to the long urethra lead-
other umbilical disorders. Ultrasonographic exami- ing to increased bladder pressure with resistance to
nation can confirm the diagnosis in selected cases. emptying) but recent evidence does not support an
increased incidence in males. Congenital defects in
Management the urinary tract include failure of the dorsal blad-
Small hernias may spontaneously shrink and close der wall to close during gestation, ureteral ectopia
over time or they can be carefully treated using with rupture or ureteral/urethral atresia and rup-
elastrator bands or, in some countries, hernial ture. External trauma or strenuous exercise are also
clamps. This treatment method is not favoured reported as causes of acquired bladder avulsion from
by all clinicians but can be a good option when the urachus in older foals. Foals receiving intensive
surgery is not feasible. Larger defects (6–8 cm) or care for unrelated reasons are recognised to be at
those that persist through to 6–9 months of age higher risk for the development of uroperitoneum
should be treated surgically. Very large hernias due to prolonged recumbency or bladder disten-
may require repair via the insertion of a polypro- sion, neonatal septicaemia and improper/excessive
pylene mesh subperitoneally. handling when standing or moving the foal. Focal
necrotic cystitis and infectious urachitis second-
Prognosis ary to ascending umbilical infections can lead to
The prognosis is very good for small hernias, good uroperitoneum. These cases may have an insidious
for hernias that require simple surgical intervention onset of clinical signs and present a greater diag-
and guarded for those that have incarcerated bowel nostic challenge. Occasionally, foals with NMS are
or need mesh repairs. unable to detect distension of the bladder and initi-
ate a micturition reflex, and these foals may require
UROPERITONEUM IN THE FOAL catheterisation for up to 7 days before function
develops.
Definition/overview
Uroperitoneum (the presence of urine in the peri- Clinical presentation
toneal cavity) is a well-recognised syndrome in the In cases of uroperitoneum where the foal is normal
young foal. Ruptured bladder is the most common at birth, clinical signs are rather non-specific ini-
cause, but disruption of the urachus, urethra or tially and progress over the first 2–3 days of life. In
ureters can also cause leakage of urine into the foals with uroperitoneum of infectious aetiology,
peritoneal cavity. The onset of signs and clini- clinical signs may be insidious and only become
cal presentation depend on the size, location and obvious as late as 5–10 days of age. Characteristic
aetiology of the defect; however, affected foals are clinical signs include straining to urinate, drib-
typically 1–5 days of age. The presence of urine bling urine and frequent posturing to urinate
in the peritoneal cavity leads to severe metabolic (stretched out stance) (Fig. 14.23). Some foals may
and electrolyte abnormalities, which are fatal if be observed to pass no urine or small quantities
not corrected. of urine (defect is small), which can be deceptive.