Mysterious Poultry Maladies: Hens Exploding & Ducks Laying Rotten Eggs

I commonly answer questions about keeping chickens, ducks and other poultry, but these two left me stumped. So I asked an expert.

by Ana Hotaling
PHOTO: Neil Howard/Flickr

I frequently hear from poultry owners around the country, contacting me out of concern for their flocks. Among the poultry questions I most commonly receive are:

  • Why isn’t my hen laying?
  • What’s causing my chickens to lose their feathers?
  • Why are my hens’ eggshells so fragile?
  • Why is my chick doing the splits?

I am always happy to help my fellow fowl farmers. After all, we are all part of the poultry-farming community and we should support each other.

This summer, however, I received two questions from poultry keepers I know in Michigan regarding conditions I’d never encountered or even dreamed existed. I was stymied, perplexed and perturbed. What on Earth was happening?

I turned these questions over to my trusted poultry authorities at Michigan State University for assistance and to learn about these previously unknown (to me) ailments.

The Case of the Exploding Hens

Katherine and I had been chatting about Big Boy’s bumblefoot and the bumblefoot she had been seeing in her own flock of layers. Suddenly, she asked me if I might have any idea why her hens were exploding.


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One of her layers very suddenly developed a severely swollen abdomen. “It was hard and hot and very red,” Katherine told me, “so swollen that it’s getting in the way of her walking.” After a handful of days struggling with this malady, the poor hen died.

When Katherine placed the hen’s carcass on her compost heap, the body burst like a balloon. “It just exploded … white slimy goop went everywhere,” Katherine said.

The next day, another hen emerged with a hot, hard, red, distended belly. That hen met the same end as the first layer, right down to the exploding remains. A third hen is now showing symptoms.

Ask an Expert

I’d not heard of any illness or condition that causes a hen’s body to explode. My mind went to peritonitis, a bacterial inflammation of the abdominal lining, or perhaps uroabdomen, a medical condition in cats and dogs symptomized by a distended abdomen.

Then again, I’m not a veterinarian or an avian pathologist, so I asked a person who is.

“My guess is gangrenous dermatitis,” said Zac Williams, PhD., the academic specialist at the Michigan State University Poultry Extension. “Gangrenous dermatitis is a bacterial infection that is typically caused by an injury or cuts through which the bacteria can enter and multiply. The bacteria produce a lot of gas and pus, which would have been seen when the birds burst open on the compost. The infection happens very quickly and generally results in high mortality.”

I shared this information with Katherine right away. She has not replied about her exploding hens, so I hope she hasn’t lost more layers.

duck breeds eggs campbell
PETER M/Flickr

The Case of the Precocious Putrefaction

John and Margie have a flock of Khaki Campbell ducks that they absolutely adore. They carefully studied all available duck breeds before selecting the Khaki Campbells for their laying ability, because John loves to bake with duck eggs.

John and Margie buy the best organic, locally produced duck rations for their flock. They dug a small pond for the girls’ use. Their duck house could double as a frontier cabin, it’s so charming and spacious.

I’ve never seen such a well-loved duck flock (outside of my own, of course).

You can imagine my bewilderment when I got a call in August from a very upset John, informing me that something was wrong with his girls. For the past week, every single egg the ducks laid was already rotten. The eggs looked perfectly fine on the outside but the yolk and albumin were gray-green and putrid.

John had ruined a batch of his special pancake batter with these reeking eggs. After that initial experience, he cracked the duck eggs into a separate bowl first, and each one was rotten.

“They’re fresh eggs!” he exclaimed. “It’s not like they’ve been sitting out in the duckhouse for months! We collect them twice a day and pretty much use them up as they’re laid. Why would they be laid rotten?”

I asked John about storage, and he confirmed that he stored the eggs on his counter, in an egg tray, bloom intact. “I use them all the time when I cook. They maybe last a day in the tray before I use them. Or at least, they used to until this.”

Bug in the Birds

Williams’ best guess is a bug in the birds. “If the eggs are freshly laid, then the duck hens probably have a bacterial infection,” he said. “Your friend will need to find the hens that are laying the rotten eggs and either get them treated or cull them.”

Williams also recommended checking any source of contamination between the duckhouse and the kitchen.

I can only imagine John’s face when I relayed to him the option of culling his flock. Those Khaki Campbells are his feathered children. Culling was out of the question. Instead, he opted for treating the entire flock with Tylan. He and Margie systematically scrubbed and sanitized the duckhouse and, just to be thorough, also washed their gardening gloves.

Within a week, the girls’ eggs were back to normal, which John was very relieved to report. He happily went back to baking and Bernaise—until the start of October, when he sent me a quick text:

“Why aren’t my girls laying?”

So grows the pile of poultry questions still left to answer.

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