Preventing and Managing Heat Stress

Have you ever unloaded a group of pigs that are heat stressed following transportation? How do you manage transportation during months of high heat and humidity to prevent or minimize heat stress and transport losses? Here are a few tips to help your pigs weather summer heat and humidity.  It all comes down to managing these three basics: water, air, and feed.


Water is a critically important nutrient for normal body function and growth and thus needs to be monitored daily. Regardless of pig age, shortly after pigs are unloaded our focus should turn to getting the pigs rehydrated. Running electrolytes through the water lines is an inexpensive way to encourage water intake and replenish the water needs in their body.  Producers should have approximately one nipple water to every 10 pigs in each pen. Before pigs arrive, check that all water sources are in working order.  A flow rate at a minimum of two cups per minute (pigs less than 50 pounds) and 1 quart per minute (market pigs over 50 pounds) is recommended.

Isoweans can be hesitant drinkers.  A great tip to helping iso-wean pigs find the water is to set the nipples to slowly drip the first six hours after arrival.  Lower the water pressure to avoid pigs being sprayed in the face when trying to get a drink. Clean cup waters frequently if they become dirtied. Nipple bars or nipple waters should be adjusted to approximately shoulder height of the pig. Keep in mind, water is a critically important resource and it needs to be checked daily.


Improper ventilation on hot days could easily become a nightmare so proper preparation before the hot days of summer is a must. Curtains and fans must be running properly to exhaust the hot, humid air inside a building and replace it with cooler, dryer air. Be sure fans are cleaned, plugged in, and are running when called for by the controller. Finally, verify that all emergency curtain drops, emergency dial out settings, backup equipment, and generators are tested and working appropriately.

In addition to maximizing fan capacity in the summer, stir fans and sprinklers are two commonly used tools in finisher buildings containing pigs at least 15 weeks of age or older. These two methods are used to take advantage of the evaporative cooling principle to keep pigs in finisher buildings more comfortable in the summer. Keep in mind that these are common recommendations—and sometimes changes specific for your barn are optimal. Make sure stir fans are on and are blowing across the room. Misters or sprinklers should be set on timers that will kick on when the room temperature is 15-20 degrees over set point.  Misters or sprinklers commonly run for a short period of time—typically only on for 10-15% of the time to allow the water to evaporate off the pigs prior to turning on again.

Avoid stressing pigs during the hottest hours on warm humid days. Thus chore the buildings, mark loads, sort pigs, etc. early in the morning and late at night. Let the pigs rest during the hottest periods of the day.


Regardless of the time of the year, water intake and feed intake go hand-in-hand. In the first 72 hours after weaning, producers should focus to make sure that an adequate supply of water is available to encourage pigs to start on feed.  However, warm weather presents some challenges in keeping nursery phase 1 and 2 diets fresh and appealing to pigs. Nursery phase 1 and 2 diets should be ordered so they can be consumed quickly to keep them fresh and appealing to young pigs. One strategy to minimize market transport losses is to take pigs off of feed 12 hours prior to shipment. If your building allows, sort pigs away from feed 12 hours prior to shipment.

There are several touchpoints during pig care where we can effectively minimize heat stress during these hot months.  Proper water access and flow rates are critically important to getting pigs rehydrated. Ensuring curtains, fans, and emergency settings are working appropriately is a must, as well as keeping nursery phase 1 and 2 diets fresh.  In summary, keep the three basis of water, air, and feed in mind when preventing or reacting to heat stressed pigs.

For any questions or concerns regarding this topic please do not hesitate to contact our Pipestone team of veterinarians and swine specialist at 507-562-PIGS.

Emily McDowell, DVM

Pipestone Veterinary Service