COLUMBIA, Mo. – As temperatures inch upward, it’s not uncommon to hear rural folks say they are “sweating like a pig.”

But pigs can’t sweat, says University of Missouri Extension swine nutritionist Marcia Shannon. Pigs would probably think they are in hog heaven if they could cool themselves by perspiring like other livestock and humans.

Producers should give pigs priority when temperatures soar, says Shannon. Pigs have few working sweat glands to remove body heat and rely on their caretakers for heat relief.

Heat stress can happen quickly in pigs over 100 pounds when temperatures exceed 80 F and relative humidity is above 50%.

Shannon offers ways to improve pig comfort:

• Feed during morning or late evening hours when there is less severe sunlight and heat.

• Provide a constant supply of fresh drinking water at room temperature or lower. Water flow should be at least 1 gallon per minute for sows with litters and 0.5-0.6 gallons per minute for finishing pigs.

• Use a hose or sprinkler to run cool water over the pigs’ skin. Let skin dry before wetting again.

• Shade and mud holes provide relief to outside pigs. When pigs roll in mud, the mud cools and coats their skin to prevent sunburn.

• Move overheated pigs away from other pigs. Wet their skin with cool but not ice-cold water. Let them dry. Repeat as needed. Pigs will lie in cool areas and seek space away from other pigs when hot. They also move less.

• Watch for stressed breathing patterns or panting, one of the first signs of heat stress. More than 50 breaths per minute indicates stress.

• Eating and digestion generate heat, so pigs eat less when it’s hot to control their internal body temperature. Add more fat to rations. This reduces heat increment and boosts energy. When doing so, increase protein in diets and add cool water to feed to stimulate intake.

High temperatures affect pigs in other ways. Heat stress reduces semen production in boars, and pigs breed less, resulting in lower conception rates.

Confinement operators also can take simple steps to reduce heat, says Joe Zulovich, MU Extension agricultural engineer. First, clean building fans with brooms or power washers. Dirty exhaust fan systems can reduce airflow by half.

Inside temperatures should be no more than 3-5 degrees higher than outside temperatures when the ventilation is adequate. If not, check and clean fans, grilles and shutters, and call a ventilation system professional.