Cats are much more sensitive than dogs to the toxic effects of lidocaine, so particular attention must be paid to the
dose and route administered (not to exceed 2 mg/kg if used locally; 1 mg/kg if given intravenously).
If there is evidence of fetal distress (i.e., fetal heart rates drop below 180 beats/min, confirmed with ultrasound or Doppler),
the local anesthetic should be performed after the hysterotomy.
Technique
There must be two teams present at every hysterotomy: one team to perform the surgery and monitor the anesthetized mother,
the other to receive and resuscitate the babies.
Due to the deleterious effects of anesthesia on the fetus(es), speed and precision are paramount to achieving a good surgical
outcome. The patient is positioned in dorsal recumbency with restraints placed on all limbs. A ventral midline laparotomy
is made from the umbilicus to just cranial to the pubis. The linea alba should be elevated before incising it to avoid accidental
penetration of the uterine wall. One gravid uterine horn and the uterine body are exteriorized.
The gravid uterus must be handled gently and with minimal traction to avoid avulsing the uterine vessels or tearing the uterine
wall. The abdominal cavity is protected from spillage of uterine contents with moistened laparotomy pads placed under and
around the uterus. A stab incision is made in the ventral aspect of the uterine body, and extended with Metzenbaum scissors.
This incision should be large enough to fit each puppy through without tearing of the wall. (Photo 2) The puppies are then
"milked" out of the hysterotomy, from cranial to caudal. Each puppy should still be in its amniotic sac, and its placenta
may be attached to the uterine wall. It is important to detach the placenta with gentle caudal traction, so as not to rupture
any of the many blood vessels located superficially in the uterine wall (Photo 3). If the placenta does not detach readily,
it is left in place until the end of the procedure. Each puppy is handed off to the recovery team as it is delivered (see, Addressing the puppies).
When all the puppies are removed from the first horn, it is replaced into the abdomen and the other exteriorized. The puppies
are then removed from the second horn via the same uterine body incision. Palpate the pelvic canal to ensure that no puppies
remain at that site. When all the puppies have been removed and before closing the hysterotomy, any remaining placentas are
removed. It is preferable that the number of placentas removed equal the number of pups. Otherwise, complications associated
with retained fetal membranes can later arise, such as acute metritis. (It is possible that they would pass naturally, but
the incidence of complications related to retained placenta following hysterotomy is not known.)
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Once all the puppies are out, the anesthetic gas can be increased. If not previously administered, an opioid may be given
at this point. The uterus should begin to contract once all the fetuses have been removed. If it does not, oxytocin is administered
IM or IV (dogs: 1-5 units; cats: 0.5-2 units).
A variety of techniques have been employed to close the hysterotomy, and all seem equally efficacious (Photo 4). It can be
closed in one or two layers, with either interrupted or continuous-suture patterns. A two-layer closure entails an appositional
closure of the mucosa and submucosa, followed by an appositional or inverting pattern in the seromuscular layers.
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