(www.ivis.org), Last updated: 21-Oct-2007. Pros and Cons of Neutering

Spaying (ovariectomy or ovariohysterectomy) has been shown to reduce unwanted pregnancies, prevent pyometra and decrease the risk of mammary gland tumors in female dogs and cats. However, increased tendency to develop obesity may occur in either species. In dogs, an increased incidence of certain cancers, aggressiveness, sedentary behavior, and urinary incontinence may develop after spaying. The ideal spay would result in positive effects from spaying with the least risk of developing negative effects. It would also result in minimal pain and immediate postoperative complications. Controversy thus continues to surround the best time and method of spaying. A major controversy is whether ovariohysterectomy or ovariectomy is the preferable surgery. The rationale for removing the uterus is that stump pyometra may develop if the uterus is not removed. The rationale for ovariectomy is that the surgery is less invasive and the risk of pyometra is minimal once the animal is no longer cycling. In several long term studies of dogs and cats under going ovariectomy, stump pyometra did not occur in any animal after surgery. Studies have also shown that there is no difference in the incidence of urinary incontinence after ovariectomy or ovaraiohysterectomy in the dog. A second controversy surrounds whether or not a midline approach or a flank approach is preferable. The advantages of the midline approach are that it is technically easier to perform an ovariohysterectomy from this approach, the incision can be quickly opened if needed, and both sides of the reproductive tract are easily accessible from one approach. The advantag