Page 892 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 867

VetBooks.ir the volume of blood loss. In general, about three common cause of penetrating wounds. Occasionally,
a horse may sustain a penetrating wound (see
times the estimated volume of blood loss should
be replaced with crystalloids. Replacement of
object over which it is jumping, such as in equestrian
intravascular volume may also be accomplished Fig. 13.1) to the abdomen when landing on an
with hypertonic saline (4–6 ml/kg of 5.0–7.5% sports. There have also been reports of shotgun and
NaCl), followed by administration of isotonic flu- crossbow wounds to the abdomen.
ids. However, when blood loss is not controlled, The pathophysiology associated with penetrating
hypertonic saline administration is contraindi- abdominal wounds will vary depending on the extent
cated. When the haematocrit is 0.15 l/l (15%) or of damage to the underlying abdominal organs and
lower or when the haemoglobin concentration is whether the inciting object has left debris or is still
<50 g/l (5 g/dl), whole blood transfusion is usually contained within the wound. Although the skin
required; however, with chronic blood loss horses wound may be fairly insignificant, there is often a
may better tolerate a low haematocrit. Clinical significantly larger amount of damage to the under-
signs and blood lactate concentrations should be lying organs.
taken into consideration when deciding whether Most of the damage created by deeply penetrating
transfusion is required. The volume of blood wounds affects the spleen and GI tract. Splenic dam-
transfusion will depend on the rate and quantity age is usually associated with marked haemorrhage
of blood loss. Autologous transfusion has been and subsequent cardiovascular compromise. There
described in the horse. is potential for intestinal perforation and leakage
Abdominal surgery may be required to control with subsequent peritonitis, and a large rent in the
haemorrhage from tumours, rupture of a viscus or abdominal wall may lead to evisceration. The pene-
leaking GI vessels. The opioid antagonist naloxone trating object is usually contaminated and, therefore,
(one treatment of 8 mg i/v) or 10% buffered neu- even if the acute trauma is overcome, there is a high
tral formalin (10–30 ml added to 500 ml of 0.09% probability of infection during the healing process.
NaCl) has been anecdotally reported as being used Any foreign material left in the wound may cause a
to control haemorrhages in horses; however, objec- persistent infection and draining sinus or may result
tive evaluation of efficacy is unavailable, and some in abscess formation.
clinicians oppose the rather drastic measure of for-
malin administration. Clinical presentation
There are usually obvious signs of an open abdomi-
Prognosis nal wound; however, the severity of the clinical signs
The prognosis is variable but often poor and depends may not correspond with the size of the external
on the cause of the haemorrhage. wound. There may be abdominal contents visible or
palpable through the wound. When associated with
PENETRATING ABDOMINAL WOUNDS damage to major abdominal organs, there are usu-
ally accompanying signs of shock. Even with severe
Definition/overview internal damage such as intestinal perforation,
A wound that breaches the abdominal skin, muscula- affected horses may not initially appear significantly
ture and peritoneum, potentially causing damage to compromised. Signs of hypovolaemic shock, endo-
the underlying abdominal organs, may be classified toxaemia, sepsis or peritonitis may develop hours
as a penetrating abdominal wound. The behaviour after the incident.
of horses makes penetrating wounds more common
compared to other species. Differential diagnosis
Penetrating abdominal wounds may be confused
Aetiology/pathophysiology with deep wounds to the abdominal musculature
Impalement of the horse’s abdomen on a sharp object that have failed to penetrate the peritoneum and
such as a fence post or part of a tree branch is a have therefore not penetrated the abdomen.