Protect livestock and pets during heat wave, WSU experts warn

Closeup of a cow drinking from a water trough.
WSU experts advise to provide animals with a continuous supply of cool, clean water.

In the historic heat wave expected to roll across the Pacific Northwest next week, daytime temperatures are predicted to spike above 100 degrees from Spokane to Seattle. Livestock and pets are at risk from extreme heat, Washington State University Extension experts warn.

“Our animals depend on us,” said Don Llewellyn, WSU associate professor and livestock extension specialist. “Livestock owners, farmers, and youth raising animals for 4‑H and similar projects should prepare for heat and dangerous conditions.”

While different livestock and pet species have specific needs, Extension experts share general suggestions to keep animals safe.

Avoid stressful handling of livestock. If necessary, only do so in the early morning hours or late in the evening.

Ensure animals in barns or sheds have proper ventilation and air circulation.

Provide shade to animals kept outside, if possible.

Provide a continuous supply of cool, clean water. Water is very important, allowing animals’ bodies to cool off and stay cool. Sufficient water is particularly important for animals that are lactating or pregnant, to ensure health of nursing young as well as newborn animals.

Watch for signs of dehydration, such as lethargy, drying of the mucous membranes and eyes, or eyes that appear sunken and dull.

Clean water is also important. Excessive heat and stagnant water can promote blue-green algae growth, which has shown to be toxic to livestock, wildlife, and humans.

In times of heat stress, it may be necessary to reduce energy intake, such as from grains and concentrates, and increase fiber in the diets of animals such as 4‑H steers and lambs. This can help mitigate heat stress.

In addition, endophyte-infected forages, such as fescue or infected crop residues, should be avoided, as they may exacerbate heat stress in cattle. Endophytes are organisms such as fungi and bacteria that live on forage crops.

Heat stress is made worse by high humidity. Animals find it more difficult to cool off in humid conditions. While the Inland Northwest does not experience high humidity during summer, the west-Cascade marine environment is more prone to higher humidity. East of the Cascades, areas of irrigated farmland are an exception and can experience higher humidity.

During and following heat stress, watch for signs of respiratory disease and digestive disorders in livestock. Wide temperature swings of 40 degrees or more between day and night can predispose livestock to infection.

High temperatures with low humidity also increase the likelihood of wildfires. Homeowners should make an emergency plan for disaster preparedness.

For assistance with livestock questions during the heat wave, contact your WSU Extension specialists, County Extension educators, Extension veterinarians, or your local veterinarian.

Media contacts:

  • Don Llewellyn, Livestock Extension Specialist, WSU Extension, 509‑335‑8759,
  • Craig McConnel, Veterinary Medicine Extension, WSU Extension, 509‑335‑0766,

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