Anesthetic management in the pediatric patient can be safe, provided appropriate attention is paid to a few basic principles and to the unique concerns associated with pediatric patients.
Given that metabolic development is largely complete by 6 weeks of age, the same anesthetic protocols that are used in adults can be safely used in pediatric patients.9,19 However, pediatric patients have lower body fat percentages, a decreased ability to shiver, and a larger surface-area-to-volume ratio. Each of these factors makes attention to the maintenance of body temperature critical. Pediatric patients are also at a greater risk of hypoglycemia. Body temperature and blood glucose concentration can be easily managed, allowing surgical anesthesia with minimal risk.9
Preoperative and intraoperative recommendations. Perform a preoperative physical examination on all patients.19 It is at the veterinarian's discretion whether the packed cell volume, total solids, blood urea nitrogen concentration, and glucose concentration are measured; however, these tests are usually not performed in the shelter environment.
According to the Association of Shelter Veterinarians guidelines for spay and neuter programs: "Warmth is best preserved by reducing contact with cold surfaces, limiting body cavity exposure, and providing carefully protected contact with circulating warm water or heated containers, such as carefully monitored water bottles or rice bags. Forced hot air or convective warming can also be an effective means of maintaining body temperature perioperatively."19 These measures in conjunction with a short surgical time and the reversal of anesthetic agents at the completion of surgery minimize hypothermia.20
Hypoglycemia can be avoided or minimized by restricting preoperative fasting to two to four hours, avoiding preoperative excitement, and feeding the patient a small amount of its regular food immediately upon anesthetic recovery.20,21
Anesthetic and analgesic protocol. Many anesthetic protocols have been recommended for pediatric surgery. Most recommend multimodal analgesia and avoid the administration of barbiturates, likely because these patients have minimal fat.22
In our experience, an intramuscular injection of a dexmedetomidine, ketamine, butorphanol combination (Tables 1 & 2) followed by maintenance with oxygen through either a face mask or an endotracheal tube and supplemented with isoflurane, if needed, is safe and effective. Following the injection, a surgical plane of anesthesia is achieved within five minutes and will last for up to 30 minutes.
Table 1: Anesthetic Drug Doses for Cats*
The dexmedetomidine can be reversed with atipamezole immediately after surgery and will frequently result in the patient being mobile within five to 10 minutes (Tables 1 & 2). We recommend administering a nonsteroidal anti-inflammatory drug, such as meloxicam, after induction of anesthesia and before the start of surgery for postoperative analgesia according to the labeled dosages for cats and dogs.23
ORCHIECTOMY IN PEDIATRIC CATS
Feline pediatric orchiectomy is performed essentially the same as castration in adult cats. For a surgeon just starting to perform pediatric surgery, the most difficult aspect is localizing and securing the testicles for incision. The choice of an open or closed orchiectomy technique depends on the surgeon's preference. We prefer a scrotal approach and a closed orchiectomy technique, which are described here.10 A closed technique is no more difficult to perform than an open technique in pediatric patients and it does not require entry into the peritoneal cavity.
Table 2: Anesthetic Drug Doses for Dogs*
Place the anesthetized patient in dorsal recumbency with the rear legs pulled forward. Clip the scrotum and perineal area of hair, and perform a surgical scrub. Grasp the first testicle between the thumb and index finger, and secure it within the scrotum.
Make a scrotal incision over the testicle, and exteriorize the testicle from the scrotum with digital pressure. Apply gentle traction to the testicle and spermatic cord while stripping the fat and fascia from the spermatic cord with a gauze sponge. Use a hemostat tie for hemostasis and excise the testicle. To perform a hemostat tie, place the tip of the hemostat under the cord and then rotate the tip around the cord. Open the jaws of the hemostat as the distal (testicle) end of the cord is advanced around and into the hemostat jaws and clamped. Next, transect the cord between the clamp and testicle by using a scalpel blade or scissors.
After removing the testicle, push the knot off of the tip of the hemostat. Tighten the knot to ensure its security, but leave about 5 mm of tissue distal to the knot to ensure that it does not unravel.
Perform the identical technique on the second testicle, and leave the incisions open to heal by second intention.10
ORCHIECTOMY IN PEDIATRIC DOGS
Canine pediatric orchiectomy is performed essentially the same as feline pediatric orchiectomy is. The surgical incision is made in the scrotum just as in the cat. In most patients, only one scrotal incision is needed. We prefer a scrotal approach and a closed orchiectomy technique, which are described here.
Place the anesthetized patient in dorsal recumbency. Clip the scrotum of hair, and perform a surgical scrub. Grasp the first testicle between the thumb and index finger, and secure it within the scrotum.
Make a scrotal incision over the testicle, and exteriorize the testicle with digital pressure. Apply gentle traction to the testicle and spermatic cord while stripping the fat and fascia from the spermatic cord with a gauze sponge. Use a hemostat tie for hemostasis, and excise the testicle.
Move the second testicle into the surgical wound and incise the fascia overlying the testicle. The excision and hemostasis of the second testicle is performed in a manner identical to that of the first testicle, and the incision is left open to heal by second intention.