Extreme Heat Is Deadly for Farm Animals — and Too Often, They Receive No Mercy

One ‘solution’ employed for overheated animals on factory farms? Mass suffocation.

image of cow drinking, how does extreme heat affect farm animals

Explainer Climate Research

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Farm animals like it cold — ideally between 25 and 77F for cattle, and 50 and 75F for pigs. As record-setting summers become the norm — courtesy of climate change — the consequences for farm animals are severe. The hotter it gets, the more production drops and transportation becomes increasingly deadly

Let’s take a look at why extreme heat is deadly for farm animals and pets alike, and what can be done to better protect them.  

How Does Extreme Heat Affect Farm Animals?

Unlike pets, farm animals spend their lives outside in the elements, including extreme heat. Exposure to increasing temperatures can have severe consequences for them as they struggle to stay cool. 

Overheating becomes a much larger problem with rising temperatures.Animals can become heat-stressed to the point that they can’t even move. At such high levels of heat stress, they also become more susceptible to diseases, and may  die if they are not cooled down adequately. 

How to Identify Heat Stress in Farm Animals

Heat stress brings with it several indicators that make identifying the condition easier. 

  • Panting
  • Increased respiration rate
  • Increased water intake
  • Loss of appetite
  • Listlessness or lethargy
  • Increased salivation
  • In severe cases, unconsciousness

What Are the Effects of Heat Stress on Farm Animals?

Heat stress comes with severe consequences for animals, including reduced fertility, increased susceptibility to disease and, in particularly bad cases, death. The deadly consequences of excessive heat for chickens has led to the culling of  millions of birds in a process called “ventilation shutdown,” in which oxygen is cut off and animals inhumanely and slowly suffocate to death.  

What Is the Tolerance of Cattle to Heat Stress?

Cattle prefer it cold, and can start showing signs of heat stress at just 80F . Now, in the name of production, efforts are underway to breed cattle who are more resilient to warmer temperatures

The enduring lack of heat tolerance in cattle results in significant economic consequences for producers, since milk production goes down. 

How Does Heat Stress Affect Milk Production in Dairy Cows?

Cows who are lactating are at greater risk of heat stress due to increased internal heat. As a result, the amount of milk produced by cows in intense heat conditions decreases. 

A USDA analysis found that rising temperatures are likely to reduce dairy production by 0.60 to 1.35 percent. Though these numbers may seem small, they equate to an economic impact of $79 to 199 million. 

As production falls due to increasing temperatures, demand is likely to continue to go up. To remedy this incongruence, producers will either need to raise more cattle, or breed cows who produce a greater quantity of milk — likely further compromising their welfare. 

The Impacts of Heat Stress on Animal Reproduction and Fertility

Exposure to extreme temperatures resulting in heat stress has severe impacts on farm animal reproduction and fertility, regardless of species. Pigs provide an example of these consequences. 

Pigs lack sweat glands, which means they struggle to remain cool in hot weather, and  are highly susceptible to heat stress. Mother pigs who experience heat stress prior to being inseminated are less likely to give birth, and if they do, are likely to have smaller litters. Like dairy cattle, sows who experience heat stress produce less milk, leading to piglets with lower body weights. 

What Types of Shelter Protect Animals from Heat?

One of the best ways to prevent heat stress from developing in animals is to provide adequate shelter that provides protection from the sun’s rays. However, not all shelters are created equal.

The best types of shelters are those that provide protection from the sun, but also allow breeze to freely flow through the structure (such as the shade from trees). 

Constructed Shelters

Some common types of constructed shelters consist of tarp, iron and timber to provide a simple standing structure under which animals can seek relief from the sun. 

Trees with Large Canopies Planted Individually in Fields

In cities, trees can have a lifesaving effect by cooling down the air by as much as 10 degrees. They are no less effective for cattle and other farm animals in fields. 

In addition to providing shade, trees can also offer enrichment for farm animals. Cattle, for example, may use trees as grooming tools. However, offering only one or two trees as shade for dozens of animals is probably not going to work, due to the risk of smothering. If there isn’t enough shade, then livestock are likely to tightly pack themselves together, running the risk of smothering one another in the heat. 

Naturally Undulating Paddocks and Gullies

The natural topography of the land can also provide safe haven from the heat. Paddocks with hills or gullies can help animals stay cool. 


Shelterbelts are long rows of trees, often behind a fence. Like individual canopy trees, they can help reduce air temperatures and provide shade for animals in a field. 

Forestry Blocks 

Forestry blocks are exactly what they sound like: groups of trees that help block the sun’s rays and cool the air, which can provide temporary shelter from extreme heat. 

Outdoor Poultry Houses

Outdoor poultry houses, or chicken coops, can act as ovens if they’re not constructed with high temperatures in mind. Some ways to consciously construct a coop include insulating the walls, especially the east and west walls, and constructing it in a well-shaded area. 

How to Care for Farm Animals in Hot Weather

In addition to providing adequate shelter, there are several other ways to prevent animals from falling victim to heat stress, as well as ways to treat livestock who have started getting too hot. 


Some general tips for handling farm animals in hot weather are to provide plenty of water, and to avoid moving them around during the hottest parts of the day. It’s also important to provide plenty of natural resources, such as water and shade, so that they are not overcrowded, and so more docile individuals are not prevented from accessing them. 


Horses areoften called upon to exert themselves in the heat, making overheating a serious concern. Though the best prevention is not to exercise a horse during the hottest part of the day, if caught early enough, overheating is treatable with rest, hydration and some water applied to their coat. 

Dairy Cattle

On hot days, misting cattle with water — or better yet, allowing them to wade into shallow bodies of water — can help prevent them from overheating. In addition, certain diets, such as those made up of grasses, will help them stay cooler.


It only takes 80 degrees Fahrenheit for conditions to become critical for some pigs; they don’t sweat and, as a result, are especially vulnerable to heat stress. In factory farms, producers can adjust ventilation and use sprinklers to keep pigs alive. However, transporting them to the slaughterhouse in the first place is more of an issue. When transporting pigs at higher temperatures, morbidity is likely to increase to  1.4 times its already-high rate.


In large part due to the ongoing avian flu pandemic, ventilation shutdown — or raising temperatures to fatal levels where animals can no longer breathe — has become an increasingly popular way of “depopulating” flocks. Birds killed this way have been recorded thrashing, vocalizing, slumping and lunging at their enclosure’s walls — seemingly searching for a way out. 


Just like livestock, common pets are susceptible to heat stress and stroke. Because they play integral roles in society and accompany people everywhere, they are often exposed to excessively hot temperatures. 

In extreme temperatures, pets should be kept indoors in a cool environment in order to prevent heat stroke. If you are taking animals out and about with you, never leave them unattended in a car that isn’t air conditioned, as it only takes a few minutes for temperatures to climb to potentially lethal levels. 


On hot days, dogs can fall victim to severely burned paws from hot pavement or heat stroke, indicated by panting, lethargy and other symptoms also seen in livestock. Generally, a good rule is to avoid walking dogs in the middle of the day to avoid causing distress. 


So long as they have access to plenty of fresh water, cats are great at making sure they don’t become dehydrated and regulating their body temperature. Unlike most livestock, they also enjoy warmer temperatures. However, that doesn’t mean they’re impervious to heat stress. Older cats especially are at risk of dehydration. To keep them healthy, offer a water fountain, and keep an eye out for reduced urine output. 

Other Pets

“Pocket pets” such as guinea pigs, hamsters and rabbits are also susceptible to heat stress. As with other animals, signs of heat stress are heavy respiration and lethargy. Breeds of rabbit with flat faces are especially susceptible to overheating.

 Risks of Transporting Animals During Extreme Heat

When it comes to heat exposure, transport provides significant risk. In the United States, millions of animals die every year on their way from the farm to the slaughterhouse. During transport, animals are tightly packed together and are often not provided with water or breaks to ensure their survival. 

How to Reduce the Risk of Heat Stress During Transport

The best way to reduce the risk of heat stress during transport is to simply stop transporting animals to slaughterhouses. However, scheduling transport for overnight, early morning or late in the evening – and reducing the number of animals on each truck to avoid overcrowding – can at least help reduce the risk of heat stress. 

The Bottom Line

All animals are at risk of heat stress, including livestock. In fact, livestock may be at greater risk than other animals, as they tend to prefer cooler temperatures and, in the case of pigs, don’t sweat to thermoregulate. Worse, heat stress has severe consequences for livestock, ranging from reductions in production, to death. 

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