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10 simple ways to recognise heat exhaustion in chickens.

Why it's potentially fatal, how to spot it in time and what to do.

When we're in the depths of winter, it's easy to forget how hot it can get in the summer.

But learning about how heat affects chickens is a potential life-saver - and it's never too early to start thinking about it.

Because the fact is that heat exhaustion and heat stroke are killers which can creep up very quickly if you're not clued into what the signs are.

So in this article, we'll look at how you can tell if your flock is becoming badly affected by the heat.

From there are some easy steps you can take to make sure that you care for your girls (and boys) equally as well in the heat of summer as the cold of winter.

Why is recognising heat exhaustion important?

A chicken's normal body temperature is between 40ºC and 41ºC (104ºF and 107ºF)^{(1, 3)}. They don't have sweat glands, so there are limits to a chicken's ability to regulate its body temperature.

Cold isn't really a problem for chickens - they have feathers to protect them - and tend to do well in the winter - even in very cold climates.

But heat can be a very serious issue.

• In areas of high humidity (above 50%), temperatures above just 20ºC (68ºF) will cause some mild heat stress.
• Above 25ºC (77ºF), heat exhaustion will increase rapidly.
• At 30ºC (86ºF) the bird will not be able to lose heat fast enough and is likely to suffer a stroke brought on by the heat.
• In areas where humidity is not an issue chickens can survive (but not necessarily be comfortable) until the temperature reaches 40ºC (104ºF).
• At that point, problems can become severe and quickly lead to heat stroke. And heat stroke in chickens generally proves fatal, if not managed properly. 

It's in those circumstances you should be aware of the signs of heat exhaustion and know how to deal with it.

Why does it happen?

Some breeds can deal with extremes of temperature better than others⁽²⁾. 

Breeds originating in cooler, more temperate climates have more difficulty in dealing with extremes of temperature. This is an important factor when considering ways of managing heat stress.

Older chickens can sometimes adapt if the temperature rise is gradual, but if it's quick they won't be able to. They're likely to suffer most.

Heavy breeds will be next in line. Broilers - birds bred for their meat - will show signs of heat exhaustion much more quickly than layers.

And broiler chicks (between 6 and 8 weeks old) have been shown to be even more badly affected by heat exhaustion than adults⁽⁴⁾.

How to tell if your flock is suffering from heat exhaustion.

These ten symptoms are given in order of seriousness, 10 being the worst. The further along your flock is, the worse the outcome is likely to be. 

1.  Panting

The first and most obvious sign of heat stress.

When the environment is hot the chicken needs to lose heat or its body just keeps heating up. The feathers, which are so efficient at keeping warmth in the body in the winter, also prevent heat escaping in the summer. 

The chicken needs to cool off by evaporation.

Because a chicken has no sweat glands, it loses the water from its respiratory system - in other words it pants to keep cool.

A panting bird will be very obvious - there is no noise coming from its beak, only moist air.

2.  Rapid breathing. 

This is related to panting and happens particularly when humidity levels are high. 

Because the air the hen is breathing out is full of moisture, it becomes harder to expel it if humidity levels are high. To compensate, the hen's breathing increases from about 20 to as much as 240 breaths per minute.

This then becomes a kind of vicious circle. As breathing becomes quicker, the bird is using up more energy and that itself produces more heat.

So the problem can escalate very, very quickly.

3.  Loss of electrolytes. 

This one is the silent killer - it's not something which can be seen, but loss of moisture from the body results in a loss of electrolytes which the chicken needs to remain healthy. 

Think of them as the energy in the battery which keeps your chicken going -  a kind of chicken Gatorade. 

Depletion of electrolytes can cause the kidneys to malfunction, the immune system to weaken and diseases to take hold - in particular respiratory disease.

It also depletes calcium stores, and can create related problems - including soft-shelled eggs (see no. 8 below).

For all those reasons - and also because electrolytes can help weak baby chicks - I keep a ready store in my chicken first aid kit and add it to drinking water when temperatures soar.

4.  Wings are outstretched and feathers more erect. 

This happens as the bird tries to expose more skin to cooler air, rather than have feathers trap the heat.

You'll often see this in hens who are dust-bathing. In lower temperatures birds will just hold the wings out from the body. As temperatures rise it can look as though they're dragging one or both wings on the ground.

5.  The bird stops eating, and drinks large amounts of water.  

A panting bird can't eat as much as it should - it's as simple as that.

Chickens (like most animals) tend to eat less in hot weather anyway. But watch out for your feed not being used in anything like the same quantities as usual. And keep an eye on individual birds to make sure they're getting some food.

In terms of drinking, if you use a product like The Chicken Fountain this won't be an issue since it provides a constant supply of water direct from your mains.

But if your waterers are the more usual type then you will see them empty very rapidly. Chickens who are over-heated will drink somewhere between four and five times their usual amount.

6.  Diarrhea. 

This is directly related to drinking more - the birds' output is likely to be much more liquidy than usual.

Why does this matter? More liquid loss equals yet more electrolyte loss, weakening of the immune system and consequently more susceptibility to disease.

7. The chicken becomes listless, droopy and disinterested.

It's hardly surprising really, is it? Think about how you feel when the weather is very hot.

Your hens are losing electrolytes, not eating much - if anything - and expelling a lot of waste products which are dehydrating them even more. 

At this point chickens are certainly showing fairly severe symptoms of heat exhaustion.

8.  Egg production is reduced or stops, and the shells are thinner than usual.

By now, the body's balance is disturbed. Food consumption is down, the chicken is working harder to breathe and expelling more waste products than usual. The body needs to use its own stores of protein, fats and carbohydrates to get by. 

The hen no longer has enough calcium supplies to lay - or if she does, you'll see the number of thin- or soft-shelled eggs increase.

And that, of course, carries its own dangers.

Never seen a soft-shelled egg? Here's a short video from a friend of mine, Tim Daniels of PoultryKeeper.com, showing what they look like.

9.  Staggering, disorientation and seizures. 

By this stage, a chicken will be very severely dehydrated. Immediate action is required if there is to be any hope of saving her. 

The bird's system is collapsing and death will not be far away.

10. Collapse of system and death.

By this stage there is no helping a chicken suffering from heat exhaustion. The loss of water and electrolytes disturbs the chemical balance so badly that the heart and lungs cannot cope and stop functioning. 

Clearly, your aim is to look for and treat symptoms long before this point is reached.

Can heat exhaustion in chickens be prevented?

Of course. Here's a quick guide of easy steps to help prevent the problem.

1. Always provide lots of water in different places around the chicken run.

2. Starting the day with a block of ice in the waterer means it will keep the liquid cool longer.

3. Provide lots of shade. Plant trees and, while they're growing, add a tarpaulin to your run where the flock can cool off.

4. Help them keep cool by providing a dust-bathing area.

5. Keep a store of poultry electrolytes, or make your own.

6. Avoid high protein foods, and do not use apple cider vinegar in the heat. Both increase metabolism and will add to the problem rather than helping it.

7. Provide low fat food with a high water content such as watermelon, and make up some frozen treats to make sure your chickens stay well hydrated.

Other summer problems with chickens?

Summer time can bring other problems with our flocks. These articles may help you sort some of them out. Just click on the pics.

Sources.

I make every effort to provide readers of my site with information which has been confirmed by scientific, peer-reviewed research, particularly where health issues are concerned.

For this article, some of the most helpful sources are:

1. Borges, S.A., et al: 'Physiological responses of broiler chickens to heat stress and dietary electrolyte balance'.  Pub.  Oxford Journal of Poultry Science, 2004.

2. Gail Damerow: The Chicken Encycolpaedia: an Illustrated Reference.

3. Rural Chemical Industries Ltd: 'Thermoregulation in poultry'. Pub. Heatstress in Livestock.

4. Tirawattanawanich, C., et al: 'The effects of tropical environmental conditions on the stress and immune responses of commercial broilers, Thai indigenous chickens, and crossbred chickens'.  Pub. The Journal of Applied Poultry Research, 2011.