Heat Stress in Sheep

(Updated: Aug. 29, 2024, 12:23 p.m.)

We are in the dogs days of summer now and with that can mean additional stress on our livestock, like heat. Sheep can be challenged by the increased temperatures that we typically experience during a South Eastern Summer. Heat stress simply means the environmental conditions exceed an animal’s ability to mitigate heat effectively. Animals have a temperature range where they are most comfortable known as the Thermoneutral Zone (TNZ). We as people have it too – my thermostat is set to 74! The TNZ is an environmental range that requires the least amount of effort by an animal to regulate body temperature. For sheep, age, fleece, body condition, housing conditions, and physiological status can all influence TNZ. Sheep are often most productive when they are in their TNZ. Decreased animal welfare is a major concern for a heat stressed sheep, but heat stress can also lead to decreased animal productivity. This decrease in productivity can be displayed as reduced feed intake, growth, milk production, meat quality, health, and reproduction.

Signs of heat stress in sheep include:
  • Crowding in shade or around waterers
  • Open-mouth breathing/panting
  • Lethargy
  • Reduced feed intake/off feed
  • Increased respiration and heart rate
  • Elevated rectal temperatures 105-107. Normal temperature is 100.9- 103.8
  • Aimless walking/clumsiness
  • Death may possible if treatment is not provided
Below are several suggested ways to help your sheep mitigate heat stress:
  • Shear in early spring if you have wool breeds. Shearing can significantly influence sheep comfort
  • Avoid handling (working) animals on extremely hot days, if possible. If you must work them, try for early morning or evening
  • Clean, cool water. Sheep are picky!
  • Keep good ventilation in barns
  • Provide shade – trees, lean-tos, temporary or permanent shade
  • Transportation – avoid overcrowding
  • Breed selection – Hair sheep tend to tolerate heat better than wooled breeds
Incorporating management practices that reduce heat stress from occurring in your flocks are encouraged. However, if you suspect a sheep is displaying signs of heat stress it is best to consult your local veterinarian as soon as possible.

For more information on managing heat stress in your flocks contact your local County Livestock Agent.