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The Pros And Cons Of Spaying

There is no doubt in my mind if spaying heifers was easier on veterinarians arms, was less costly for producers, and the death loss could be all but eliminated, there would be much more of it performed in the cattle sector.

Since BSE, we are seeing bulls left out longer and more unwanted pregnancies showing up in the feedlots, which is creating issues with calving-related problems. Spaying does eliminate these problems.

Historically, at the turn of the last century, spaying was done through the midline just ahead of the udder with heifers either pulled up with ropes or strung out like team ropers now do at rodeos. Even then they recognized the need to prevent certain females from cycling and getting pregnant. These pioneers spawned the modern spaying techniques in the veterinary profession.

Spaying next evolved to a small flank incision, whereby long scissors, through this flank incision, were used to cut and remove the ovaries. To be efficient and humane, animals were prepped in one chute and the surgery performed in the next. The advantages were the total removal of ovaries and nothing was done blindly. The procedure was slow (20 head per hour was considered fast) and scarring was left in the flank creating trimming losses at slaughter. Usually one or two large sutures closed the incision.

Spaying next progressed to where we are today with devices used through the vagina and the ovaries cut off blindly. Heifers need to be starved for at least 24 hours and the procedure needs only one chute. Speed of the procedure approaches double the flank technique (up to 40 head per hour in experienced hands).

The two instruments, which can be used, are the Kimberly-Rupp spay instrument and the Willis spay instrument. The first is a tube-like instrument, which is popped into the abdomen through the vagina. A chamber is opened the ovary is popped into it cut off and removed. This is repeated on the other side and the chamber is checked to make sure both ovaries have been removed and there is no gut present. Seeing part of the intestine means the gut has been perforated, which is not a good thing. The starving shrinks the rumen and intestines pulling them out of the pelvis area and minimizes the chances of gut perforation. We always cover with antibiotics in case any infection has been introduced.

The Willis instrument is a simple tool, light and well machined, which has a slot opening in the end. The object is to pop it through the vagina just above the cervix. With the instrument free in the abdomen, one hand manipulates the instrument and the other gloved arm in the rectum guides each ovary through the drop slot. The Willis spay instrument is pulled back, the ovary is held and cut off. The ovary subsequently drops off into the abdomen. This procedure only has the instrument being introduced into the abdomen once, so infection is reduced. The drawback is that the procedure is all done blind and the bowel can be lacerated.

The major advantages to spaying include increased gains, especially if the spayed heifer is also given a steer implant at the same time. No cycling can also increase gains if the whole group, whether at pasture or in the feedlot, have been done. In instances where breeding heifers and feeder heifers are run together, only the replacement heifers will get bred. The gains carry over to the feedlot by eliminating undesirable pregnancies coming into the yard.

Spayed heifers can also be run with steers at pasture. Studies done in the early 1990’s showed up to a $75 per head advantage with implanted spayed heifers over controls.

Spaying has become somewhat of a lost art, as very few veterinarians did them or did enough to become very proficient. With less experience, the death loss might creep up from lows of 0.25 per cent up to two per cent, which creates a huge difference in the overall profit picture. Most deaths were due to perforated bowels, but occasionally animals would bleed to death.

I know when I spayed pregnant cattle years ago, we still went ahead and spayed them as long as they weren’t greater than six months pregnant. They all aborted uneventfully. The one animal death from blood loss, occurred in an open heifer. With greater proficiency came greater speed, but even then with small heifers there were limits to how many could be done in a day. The procedure was hard on palpator’s shoulders and wrists, as a great deal of dexterity was needed to perform this procedure. A few heifers could become “poor doers,” due to chronic infection, although this was rare as the procedure was covered with antibiotics.

Other countries such as Australia even spay feeder cows successfully and a classmate of mine developed a longer instrument to be used on cows, but found death loss higher.

This article will hopefully refresh some facts about spaying. If anyone wants females spayed, the big task would be finding a veterinarian, as today all the veterinarians, who used to do it to any degree in Alberta, have retired. If the need is there perhaps the new generation of veterinarians will take up the task.

Roy Lewis is a practicing large animal veterinarian at the Westlock Veterinary Center, north of Edmonton, AB. His main interests are bovine reproduction and herd health.

About the author


Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.



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