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When, Why & How to Induce a Sow

Thursday, August 13, 2015

Breeding Stock Health & Nutrition

By Rhonda McCurry

It’s farrowing time and you’re anxiously waiting for your favorite sow to begin showing signs of labor. You know the due date and you’re keeping watch to help her pigs arrive safely.

It’s normal to be anxious just before a sow’s due date.  Todd Price, a veterinarian in practice at North Central Veterinary Services in Upper Sandusky, Ohio, says knowing the sow’s exact breeding date is the key.  He raised pigs in high school and by the time he finished vet school in Ohio in 1992 he had grown his business to 100 sows in a farrow to finish operation. Price has since expanded his hog operation to a production system that finishes 22,000 head of commercial pigs annually, as well as having 30 show sows.

“In the show pig world it’s not difficult to know the breeding date because they typically AI,” Price says.

Here is Price’s advice on when, why and how to induce a sow.

Only induce a sow when you absolutely have to.

Farrowing pigs means being there in person while the sow’s giving birth. If you’re going to be out of town or have a commitment away from the barn then it might be justifiable to induce the sow so she farrows before you leave, but don’t do it unless it is the only option.

Never induce more than three days before her normal due date.

While some sows vary most are 113 to 115-day gestation and some are as long as 117 days. Price says if she has passed her first lactation then you’ll know what her normal gestation length is. If she went 114 days as gilt then it will be within a day of that when she farrows as a sow.

Use a Prostaglandin F2 Alpha drug like Lutalyse or Estrumate.

Price says he uses Estrumate most often because it is more natural and there are not as many reactions by the sow. He says he likes the drug because it induces sows more calmly and predictably but Lutalyse is also a choice for inducing females.  Estrumate is dosed at 1 cc IM while Lutalyse is dosed at 2cc IM.

Be watchful of normal signs of labor.

Look for signs of labor to start at 20 to 26 hours after the induction injection. The sow should stop eating, drop her udder, lay down and begin having abdominal contractions. Her mucus plug and fluids will be expelled just as the birthing process starts. If the sow doesn’t start labor within 26 hours after giving Estrumate and she has milk then give her 1 cc of oxytocin. If she does not have milk then wait two hours and reinject her with one CC of Estrumate.

Induction does not come without problems.

It was common in the commercial industry several years ago to induce the majority of sows in order to attend the farrowings. However, these litters were found to have a mild increase in the number of stillborn pigs and an increase in scours that led to lighter pigs at weaning. This increase in scours was attributed to lower colostrum intake on day 1 and thought to be from pigs being slower to get up and moving shortly after birth.

Misconception in the industry. 

Price says there is a misconception that pigs will get too big if the sow goes five days over.

“It’s just not true,” he says. “Pigs do not grow a significant amount inside the sow those last seven days. Instead they are actually getting ready to be born. They are developing and maturing their lungs, and other organs, not growing in size. Two-thirds of fetal growth is in the last trimester of pregnancy, but virtually none of it is in that last week.”

Have backup or second shift help so you don’t have to induce.

Many commercial sow operations have a second shift crew on hand to farrow sows. Price says when the pigs come out it’s very important to get the pig dry and keep it warm. The simple act of drying the pigs off with a towel will help immensely.  Then, place them under a heat lamp that is 95 degrees at floor mat level in the farrowing crate. He even likes to use a hot box with a drying agent like Mistral on the bottom so they can be warm and get their feet under them.