| Females: |
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First estrus occurs as early as 3 mo of age in gilt piglets. The lack of estrus or a distended abdomen in a young gilt may be due to pregnancy if she has been exposed to littermate boars. If the female does not cycle, the abortifacient prostaglandin F2a, given as 2 injections (8 mg and 5 mg in a 25-kg pig) 12 hr apart, can be administered when corpora lutea have become susceptible to luteolysis after day 13 after estrus.
Estrus should occur 3-7 days later. |
| Dystocia is another reproductive problem in PBP. Because the birth canal is too small for inspection for unborn pigs via palpation, radiography or ultrasound may be indicated to reveal undelivered piglets. Oxytocin (5-10 U) may be used to aid delivery if the vaginal canal is patent. The decision to perform a cesarean section, if indicated, should be made promptly, before the sow becomes toxic and has friable uterine tissue and vessels. Cesarean section may be performed by
several approaches, but the right flank approach has 2 advantages: the piglets nurse away from the incision, and gravity pulls the incision shut, minimizing the chance of dehiscence. However, regardless of surgical approach, surviving piglets will probably require hand-raising. |
| Ovariohysterectomy ideally should be done in PBP at 4-6 mo of age. Older female PBP generally display irritable behavior for 2-3 days of estrus out of every 21 days of the estrous cycle. Performing an ovariohysterectomy during estrus is a formidable task because of the tremendous vasculature in the broad ligaments of the horns of the uterus, and surgery should be delayed until ~7-10 days after estrus. Early spaying may also reduce the risk of ovarian cysts, uterine tumors, and
cystic endometrial hyperplasia. An obviously distended abdomen accompanies large ovarian or uterine masses (≥20-30 lb). Vulvar hemorrhage may be a sign of uterine tumor and can be life-threatening. Although most ovarian or uterine masses can be surgically removed, some are so extensive and invasive that euthanasia is required. A distal midline approach, as if performing a cystotomy, has been routinely used for ovariohysterectomy because it is more difficult to expose the cervical
end of the reproductive tract than the ovarian end. Penetration of the cervix by sutures should be avoided when ligating the uterine stump to prevent intermittent postsurgical hemorrhage from the vulva. A right flank approach may be used in extremely obese PBP, in which wound dehiscence could be a complication. Isoflurane anesthesia provides excellent muscle relaxation. Malignant hyperthermia (
Malignant Hyperthermia : Introduction) has been reported only once in a PBP under
isoflurane gas anesthesia, so it is thought to be rare in PBP. Because some PBP may become apneic when placed in prolonged dorsal recumbency, intubation is preferred to masking; however, PBP may be difficult to intubate, and prolonged efforts at intubation may cause laryngeal edema and postsurgical complications. |
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| Males: |
| PBP boars retained for breeding should be kept in secure pens; they should not be kept as pets because of the unpredictable behavior of boars around other animals or people. Neutering is usually performed at 8-12 wk of age, using injectable or isoflurane anesthesia. One protocol for injectable anesthesia is xylazine at 2.2 mg/kg, IM, followed by tiletamine-zolazepam at 6.6 mg/kg, IM, both injections in the hams. Determining whether both testicles are descended before surgery is
important because cryptorchidism is seen in PBP. An inguinal hernia is another possible complicating factor. The midline skin incision is made cranial to the scrotum, and structures such as the vas deferens and blood vessels are ligated and excised similar to the procedure in dogs. Both inguinal ring areas should be closed to prevent herniation after surgery. Removal of tunic, cremaster muscle, and extraneous subcutaneous tissue, followed by closure to obliterate empty space,
will help prevent seroma formation. At the time of castration, the preputial diverticulum or “scent gland” may be removed by eversion and excision to minimize the pooling and discharge of foul-smelling preputial fluid after castration. Umbilical hernia may complicate removal. Tetanus antitoxin (if no current tetanus toxoid vaccination) and antibacterial injection are given after surgery of the reproductive tract.
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