For the first time in a week, Evan Zimmerman of Schaumburg finally should be able to sweat like a pig.
Pigs don't sweat, and with today's temperatures expected to plunge into the tolerable 80s, Zimmerman, the farm operations coordinator at the Volkening Heritage Farm in the Schaumburg Park District, won't be sweating as much either. But it was a rough week leading up to today -- for the swine and for their caretaker.
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Water is the savior.
"I'll use my thumb and spray it up like rain and let a little bit get on me and a little bit on them," says Zimmerman, 29, who lets the hose run a half-hour or so to make a nice mud pit for his two sows, one boar and 10 piglets. "With the way the heat is now, we're doing it about every other day."
While humans sweat like race horses, pigs need mud.
"They are not big sweaters," Janeen L. Salak-Johnson, an associate professor at the University of Illinois at Urbana-Champaign, says. "They do have sweat glands. They are just not functional. They do not sweat through glands on the skin."
As refreshing as humans find a dip in the pool, pigs get even more benefit from a wallow in a mud pit. In addition to the water evaporating from their skin and cooling them down, the mud acts as protection against insects and as sunscreen.
"Believe it or not, pigs are very susceptible to sunburns," says Salak-Johnson, who teaches classes and conducts research in the department of animal sciences.
"Pigs don't have a lot of pigmentation," says the professor, bringing to mind the irony of the pig nation lacking pigmentation. "Even with pigs that are dark in color, it's not their skin, it's their hair."
"You have to have some shade for them to cool," says Zimmerman, as he rounds up the piglets that often can be found frolicking in the shade of a nearby shed.
The adult pigs spend a lot of time inside their shady housing units or lying in one of the mud holes Zimmerman made for them.
"It's like us," Zimmerman says, comparing the behavior of hogs and humans in the heat. "The big ones, they're not going to be running around like those little ones."
Commercial farmers use giant fans and "snout drippers" that drop water onto the pigs' noses to help cool the animals, Salak-Johnson says.
"It's very easy to heat stress your older animals," she says.
Even if they can't sweat, pigs are very good at "behavioral thermal regulation," meaning they wallow, spread out to catch a breeze, stay in the shade, eat less and drink more during hot weather, the professor notes.
"They're not only good sweaters," Salak-Johnson says of cattle, "but they can pant."
Zimmerman sprays water on the cows and horses at the farm during the heat spell. The horses need extra care.
"We walked them over to the nature center and back, and they were sweating," Zimmerman says, pausing before grinning and adding, "like hogs."
The history of that "sweating like a pig" phrase is debatable, with some linguists arguing that it refers to the drops of moisture that appear as the hot metal known as pig iron cools. Even if living pigs don't sweat, the phrase "eat like a pig" still rings true, says Zimmerman, who says his hogs are pigging out on cracked corn and a special hog feed even in hot weather.
Pigs generally have a body temperature of 102 or 103, about four or five degrees warmer than humans, Salak-Johnson says. But extreme heat with high humidity can push a pig into dangerously hot internal temperatures.
"Then," she says, "it essentially will cook its body."
Given the number of rib fests and barbecues that went on despite the heat, that is a pig trait with which suburbanites are familiar.