Can't find what you're looking for?
Search this site!

Sudden Chicken Death Syndrome: Why chickens sometimes seem to die randomly.

Sudden chicken death syndrome: what it is, why it happens, and what you can do about it.#backyardchickens #chickenproblems #backyardchickencare #suddenchickendeath #raisinghappychickens

One minute you have what seems like a perfectly healthy, happy chicken running round the yard eating normally and enjoying life.

The next thing you know she has suddenly died.

What's all that about? 

In this article I look at the evidence about Sudden Chicken Death Syndrome: what it is, why it happens and whether there's anything we can do about it.

If you've lost a chicken in what seems to be a strange, unexplained way, this information might help you come to terms with your loss a little more easily.

I lost a chicken today.

So what?

It's not that unusual, is it?  I mean, everyone loses chickens. It's the way of the world, part of the normal cycle of life and death, something that happens to us all.

And it happens to chickens more than most species. They get killed by predators, or taken by disease, or become egg bound, or get mites, or Marek's disease, or any one of a number of other things.

Except - this one didn't.  This one was what many veterinarians and scientists in the poultry health world refer to as "Sudden Chicken Death Syndrome"(1).

The Sad Story of Sophia Lor-hen.

My Golden Laced Wyandotte hen who became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.Meet Sophia Lor-hen - a victim of Sudden Chicken Death Syndrome.

Like most Golden Laced Wyandottes, this hen was a great beauty. So I called her Sophia Loren after the great Italian film-star. 

But, as she was her own chicken-personality, we changed that to Lor-hen.  I also have a very handsome Golden Laced rooster called Spartacus and the two of them were inseparable.

Together, they ruled the roost with a rod of iron. 

My Wyandotte rooster - inseparable from the hen who became a victim of 'Sudden Chicken Death' Syndrome. Find out what it is, why it happens and what, if anything, you can do to prevent it.Spartacus - he was Sophia's constant companion and protector.

She was a young hen who I'd hatched myself in February. Even then, she stood out from the crowd. 

This Golden Laced Wyandotte chick became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.Even as a tiny chick Sophia Lor-hen stood out from the rest (she's the brown-tinged one at the front).

She was only nine months old when she died.  

She was laying well. She was fit, healthy, a good weight and showed no obvious signs of distress.

So why did I find her body in my chicken run this morning?

I'd let her out first thing and she was fine, just like any other day.  But by lunchtime she had died.  At first I thought she was asleep.  Then I realised she wasn't breathing.

But - I would have known about it had she been ill - wouldn't I?

At the time, i was in the middle of training my Livestock Guardian Dog, Luce, how to behave with my flock. For the last several weeks I'd been spending at least three hours a day in the run - usually more.

None of the flock, including Sophia,  showed the slightest signs of any illness.  No coughing, no rasping, no foaming at the beak, no dull or runny eyes, no limping, no mites, no impacted crop, nothing around the vent area, no signs of runny or bloody poop - nothing. 

She was, at least to my eye, fit and healthy.

My Golden Laced Wyandotte hen who became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.This picture was taken the day before she died - fit, healthy, pecking around with the rest of the flock, eating and drinking as normal.

Could it have been a predator attack?  Nope.  I've had a few of those so I know what that would look like.  Feathers everywhere. No signs of a body.  Or, if the attack was by a member of the weasel family (we have pine martens here in Italy) the scene would be of total devastation.

Any remaining chickens would be terrified out of their little chicken minds.

This was different.  No blood, no feathers, no signs of a predator dig nor any signs of my chain link fence having been breached. Her feathers were intact, her neck was intact, she had no puncture marks, she showed no signs of having been in distress. 

She was, simply, asleep in the warm Italian sun.

Could it be the temperature?

What about heat, perhaps?  Or cold?  Both can have devastating effects on poultry if not properly dealt with.

But no.  We are in the middle of a mild Italian autumn. The temperature is hovering around a very pleasant 26ºC,  78ºF. There's no rain, it's not humid, the coop is dry and has excellent air circulation.

So what could it be?

Possible causes of Sudden Chicken Death.

There are several things it might have been.  Chickens are very good at disguising illness and death can come notoriously suddenly.

Without performing a necropsy - the poultry version of the human autopsy - it's impossible to know exactly what happened to Sohpia. A thorough external examination disclosed no obvious causes. 

So what could it have been? 

These are viewed in studies (1) as the commonest causes of sudden death in poultry:

  • A hen may be egg-bound without it being obvious. This, though, is very unlikely in Sophia's case - she was showing no signs of pain and she had been laying normally right up until this morning.
  • A bird may have been trampled by another chicken and suffered internal damage. Also unlikely in this case. She was top of the pecking order.  She was the largest hen in the flock.  If anyone was going to do the trampling, it would be her.
This Golden Laced Wyandotte chick became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.Even at just seven weeks old, she knew she was top of the pecking order.
  • Most commonly, a chicken may have had a heart attack, or heart failure.  Often when this happens it's male birds who die and will end up lying on their back. Neither of these factors applies here - but heart problems are a possibility.
  • To be able to confirm Sudden Death Syndrome as the cause of death, the hen would be seen to have had convulsions and extreme wing-flapping for just a few seconds before she died. I hadn't been in the run when Sophia died so I have no way of knowing whether that was the case with her.

What could cause heart problems in Sudden Death Syndrome?

This condition is often found in commercially produced 'broiler' hens who are made to put on weight very quickly so that they can be killed and sold within weeks of hatching. 

Clearly that is not the case here - my hen was part of a small, backyard flock and had put on weight appropriately over the nine months since she hatched.

However, I considered the most common potential causes of heart disease found in commercial hens as follows :

  • Excessive light: Commercial birds are kept in more or less constant daylight conditions all year round, to force them to be more productive. My hens have only natural light - I don't even use artificial light in their coop.
  • Diet high in glucose: Commercial poultry are fed pelleted food high in glucose so they put on weight quickly. My hens have organic feed, and occasional appropriate treats such as mealworms, lettuce and sunflower seeds. So, not a likely cause here.
This Golden Laced Wyandotte hen became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.Adding glucose to a chicken's diet may cause heart disease. Adding some fresh fruit as a treat will not. My flock always enjoy a fig warm from the tree which grows in their run.
  • No exercise: Sophia Lor-hen, like all my chickens, had a very large run where she can scratch around from dawn to dusk. The flock is also allowed to free range over several acres when our Guardian Dog is there to supervise.  So lack of exercise does not apply here.
  • Stress: It may seem strange to some people to talk about chickens being 'stressed', but of course they can be.  Commercial birds  are kept in far from ideal conditions where they're cramped together, not allowed to scratch or forage.
  • This causes an increase in lactic acid which in turn, particularly when it carries on over an extended period, causes heart failure.  Sophia did not seem stressed - indeed as the top of the pecking order she was probably the least stressed of the whole flock.
  • I did wonder whether the presence of Luce, my Maremma Guardian Dog, had caused her stress. Sophia appeared to be quite inquisitive about Luce but not overly frightened and would often spontaneously come with Spartacus to 'visit' in the part of the run where Luce has her kennel. At the time of Sophia's death Luce was never alone with the hens and I did not observe any stress - but that doesn't mean to say it wasn't there.
Luce, the Maremma Livestock Guardian Dog, in the chicken run. Could her presence have contributed to my hen's sudden death?Luce the Maremma Guardian dog is normally very laid back around the flock and at only 9 months old is never left with them unsupervised - but could her presence have caused stress nevertheless?

So if it wasn't any of these things, what did cause this sudden death?

Well, sometimes death is just part of life - the way of the world.  Sometimes, even with the best care, a wonderful coop, the best food, the nicest occasional treats, a good place to scratch and peck - sometimes none of that matters.

It's just the way it is.

I admit, I find that hard to accept.  So does anyone who has ever had a chicken, or any other animal, die suddenly and without obvious cause.  I like to be in control of things, to understand why something happens.  I don't like not to have answers. I wanted to know why Sophia Lor-hen died.

But sometimes we just have to accept - it's likely to have been "one of those things".

So - what could I - what could you - have done differently?

That's always a question we all ask ourselves when something like this happens. But in this case, and many others like it, I honestly believe - nothing.

Even if it were a case of Sudden Chicken Death Syndrome, research indicated little that can be done short of those things I have already mentioned. 

But here's some things that both you and I can consider in the future care of our chickens.

  • Adding some sunflower seed or oil to the diet appeared to help in some cases - but in this case, she was already being given these as a treat.
Sunflower seeds may help prevent sudden chicken death syndrome.
  • After the event, keeping an eye on the rest of the flock is a given. If there were some kind of infection, I would see more deaths in the few days following. (Follow-up, twelve weeks later - there were none).
  • I could of course have performed my own chicken necropsy - the poultry version of an autopsy. So I could have used the scalpels I keep in my First Aid kit and opened her up. I might have found something. Perhaps she was egg bound without my having realised it. Perhaps she was infected in some way. Perhaps her lungs were struggling through some illness that I couldn't see, or hear.
  • But I have to hold my hands up. I don't have the stomach for that. Maybe at some time in the future, with some other chicken, I might. But with Sophia?  I just couldn't bring myself to do it.

What can you and I do now?

When any of us has any animal who dies without warning - or indeed dies at all - there are some things we can do.  Here's what I did - and these are all things you could do in the same circumstances.

  • I reminded myself that Sophia had had a good life with me. She was raised in a nice warm house when she was little and when she was big enough she went to live outside in a large, clean, comfortable, stone built, real Italian chicken house.  
  • She had a lot of land to range in. She ate figs ripe from the tree, still warm in the Italian sunshine. She had friends around her and a rooster or two to look after her.
This Golden Laced Wyandotte chick became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.She had friends.

She had a seven foot high, three feet deep strong chain link fence to keep predators out and, to be extra sure, she had Luce the Maremma as her Guardian angel. Knowing this, I know she will never have felt unsafe in her short life.

Her run and the land she free ranged on was in a peaceful Italian valley, where the leaves are just starting the change colour, and the air is warm, and the village looks down benignly and keeps its eye open.

And, perhaps most importantly, she was loved. 

She was a lucky hen.

Has Sudden Chicken Death Syndrome hit you?

If you've been affected by this, please know that, if you take good care of your flock, if you keep them clean, watered and fed well, if you protect them as best you can from rodents and predators, if you don't expect them to lay you an egg every single day for years and years, if you spend time with them so you notice any ailments or problems as soon as they arise, if you can hand on heart say all this, then...

There is no more you can do. Don't beat yourself up. These things happen. It's hard, but we need to look at the positives your chicken had while she or he was with you.

In  the end, that's all any of us can hope to say. I know Sophia lived a good life and died peacefully, her head resting on the warm Italian soil where she loved to scratch for bugs. She provided some rich, healthy, warm eggs during her lifetime. She made me laugh when she bullied my tiny bantam roosters and she made me cry when I found her body this morning.

That's just the way it is. It's hard, but it's life. 

I lost a chicken today.  

But by hatching, raising and keeping her safe I gained so much: I gained all there is that is good and healthful about keeping chickens in my back yard.

Sleep peacefully, Sophia Lor-hen.  You were a good chicken.  Thank you.

This Golden Laced Wyandotte chick became a victim of 'Sudden Chicken Death' Syndrome. Here we examine what it is, why it happens and what, if anything, you can do to prevent it.

If this page has affected you because you've lost a member of your flock ...

Clickable link to my 'In Memoriam' page.

You may find it helpful to have a look at this page too.  When my chickens were killed by a fox family in 2013, I couldn't find anywhere I could write something in memory. 

So I made one myself.

If you follow my link by clicking here, or on the picture to the right, you'll be taken to my page where you'll be able to read some chicken 'In Memoriams' and, if you'd like, to write one yourself.

Here are some articles about keeping chickens healthy. I hope you find them useful.

What do chickens eat? From birth to death, here's the lowdown.
Clickable link to getting rid of rats and mice from your chicken coop.
Clickable link to frequently asked questions about hatching chicken eggs.


In order to give the best and most accurate possible information about chicken diseases, I rely not on 'word of mouth' but on scientifically proven, peer-tested authorities. The sources below are the specific publications I have consulted when learning about Sudden Chicken Death Syndrome.

Government of Saskatchewan : 'Poultry Health and Disease'.  November 2007.

M. F. Siddiqui et al : 'Sudden Chicken Death Syndrome - An Overview'. Post Graduate School of Veterinary and Animal Sciences; published in Veterinary World, Volume 2, November 2009.

UK Department for the Environment, Food and Rural Affairs (DEFRA) : 'Poultry Farming: Health Regulations'.  June 2013.

If you found this helpful, please take a few seconds to share it - thank you!

Link to Raising Happy Chickens home page.