Ovarian Cancer in Backyard Chickens

February 24, 2020

I’ve wanted to write this post on ovarian cancer in backyard chickens for a while. But it has taken me some time to do the research so that I can share it with you today. Lately, there is quite a deal of discussion on social media forums about how to deal with hens that experience ascites. Please realize ascites, or “water-belly”, is a symptom, not a diagnosis. Often when drained, the ascites will return because the underlying problem is still present.  Sadly in many egg laying hens, ascites is due to ovarian cancer. Ovarian cancer in hens is not uncommon. In fact, it is thought that approximately 5-35% of egg laying hens will develop this condition in their lifetime.

Understanding Ovarian Cancer in Chickens

Let’s look at the background. This will explain what is happening and explore possible ways to prevent ovarian cancer. I might be turning some of the information from the backyard chicken world upside down. But these discussions are important for us to have, because these are more than “just a chickens” These are our pets.

As many of you know, chickens live an average to 5-8 years. Naturally, pullets begin to lay eggs around 5 months of age and continue to lay (depending on their breed) anywhere from 200-400 eggs until they turn 2 years of age.  After the age of 2, hens will continue to lay approximately 200 more eggs in their natural lifetimes. Currently available research on ovarian cancer in egg laying hens begins at the age of 2.  Subsequently, this is when hens begin to become susceptible.  By far the biggest risk factors that it comes down to is– the more eggs produced in your lifetime, the higher the risk for development of ovarian cancer.

The chicken is the only animal in the world that develops spontaneous ovarian cancer as humans do.

Oyster Cracker developed ovarian cancer

Ovarian Cancer in Backyard Chickens: Risk Factors

Egg Laying

There have been a few studies done in which hens are divided into two egg laying groups. For example, in one group, some hens received an injection of progestin. This hormone ceases egg laying production. Not surprisingly, this treatment was shown to decrease the development of ovarian cancer by 90%.  In another study, a researcher examined wild-type birds verses birds whose ovulation had been restricted. Similar results were seen that have allowed researches to correlate that a higher egg laying rates with a higher risk of developing ovarian cancer².


When studying diet, researchers examined a caloric diet restriction that cause a decrease in the number of eggs produced by hens. In this study, they found a five fold decrease in the development of ovarian cancer. Furthermore, the chickens that had an unrestricted diet produced approximately 64% more eggs.  In another study involving hens, some were fed a diet that consisted of 10% flax seed enriched diet for four years. These hens showed a reduction in the severity and incidence of ovarian cancer.  Incidentally, flax seed is what the commercial egg companies feed their hens to get Omega-3 fatty acids into the eggs.  Lastly, there is some thought that having a diet high in soybeans can effectively “turn on” genes that are associated with reproductive cancers. Soy is high in plant estrogens (phytoestrogens) called isoflavones.

Hens in the wild, unaffected by man’s breeding, lay 10 – 15 eggs per year.

Genetics/Breeding for Characteristics

Finally, genetics play a key role. As you know, chickens are prized for their eggs and often the more productive a hen is, the higher her worth to the farmer or chicken keeper. Often, I hear stories from folks that keep chickens primarily for their eggs. Consequently,  they turn over their flocks every two years or so. This is the same practice with commercial farmers. For example, egg laying hens in factories are considered “done” at about 18 months of age. As a result, hens have been selectively bred to produce eggs, up to 240 eggs per year on average for the typical backyard chickens. Lastly, did you know that chickens in the wild only lay 10-15 eggs per year?

How to Prevent Ovarian Cancer in Hens

I have lost a couple of hens to ovarian cancer over the years. For some, one of the first signs is that they will begin to walk with a wider gait. Their legs appear further apart. Subsequently, when you feel their bellies, they feel like a water balloon. Sadly, it’s hard to tell at first as, they can hide a lot under all those feathers. A regular exam of their abdomen can help assess for fluid.

Unfortunately, there is no cure for ovarian cancer in hens. But some of these things may help. Perhaps these steps might curtail the development of ovarian cancer.

  1. Consider purchase of breeds that are not heavy egg layers.
  2. Allow hens a natural break in the winter from laying eggs.
  3. Omit artificial lighting in the chicken coop to stimulate egg laying.
  4. Allow hens to go broody because this also allows for an egg laying rest period.
  5. Consider adding flax seed to their diet.
  6. Consider restricting their caloric intake. (Approximately 1/4 cup chicken feed per day/hen)
  7. Consider feeding your flock a soy-free alternative.
  8. Explore alternative protein sources for your flock other than soybeans.
  9. Consider reaching out to the major national chicken feed manufacturers and requesting them to develop/provide a soy-free feed or one that includes flax seed.
  10. Weigh going organic to avoid exposing your flock to unnecessary pesticides and harvesting by-products including glyphosate (a known carcinogen) and GMOs (genetically modified organisms).
  11. Likewise, increase free-ranging your flock to diversity and supplement their diet.
  12. Furthermore, share this information with fellow chicken keepers.


Oyster Cracker developed ovarian cancer.
In memory of Oyster Cracker

Please know that this post is intended for informational purposes only and does not substitute for advice from a licensed veterinarian.



1: Oral contraceptives decrease the prevalence of ovarian cancer in the hen.
Treviño LS, Buckles EL, Johnson PA
Cancer Prev Res (Phila). 2012 Feb; 5(2):343-9.
2: The restricted ovulator chicken: a unique animal model for investigating the etiology of ovarian cancer.
Giles JR, Elkin RG, Trevino LS, Urick ME, Ramachandran R, Johnson PA
Int J Gynecol Cancer. 2010 Jul; 20(5):738-44.
3: Reduction of ovarian and oviductal cancers in calorie-restricted laying chickens.
DK, Barnes HJ, Anderson KE, Petitte JN, Whitaker R, Berchuck A, Rodriguez GC
4: Long term consumption of flaxseed enriched diet decreased ovarian cancer incidence and prostaglandin E₂ in hens.
Eilati, Erfan; Bahr, Janice M; Hales, Dale Buchanan
Gynecologic oncology, ISSN: 1095-6859, (2013)Vol: 130, Issue: 3, Page: 620-8


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36 thoughts on “Ovarian Cancer in Backyard Chickens”

    • There are many feed brands that are soy free. A quick google search will help you to discover brands that are available to you based on your geographic location. Keep me posted with what you decide. Always so good to share with one another.

  1. Melissa, I believe that is what happened to my Sunshine. It showed up when she was 2 1/2. Thank you for this article. I will take some of your suggested steps. My old girls (two remaining of my first flock) will be seven in April. Interestingly, they were the two who spent a lot of time being broody. My little girls will be one year the end of March. I wonder how much flax seed I could give them as a supplement.

    • Hello Susan, I’m so sorry to hear about Sunshine and happy to hear that some of your girls are doing well at 7. The Flaxseed in the studies was given at a rate of 10% of the feed. I hope that this helps and I’m so excited for your little ones too! It is fun to have a flock of mixed ages.

  2. Not sure why doodle died. But she didn’t have any of the signs of the common chicken illnesses. She did have a prolapsed vent about 4 months ago. I took care of that. She laid enormous eggs. I did notice her belly looked swelled. Her appetite was good until the night she died. It looks liked she went in her sleep. The rest of the flock looks fine. She died have a grayish diarrhea. She was also listless with ruffled feathers. She was 1.5 to 2 years old.

  3. I’m pretty sure my Buff Orpington Goldie had ovarian cancer. Everything you mentioned about the gait and water belly sound just like Goldie. I had researched and found the info on ascites. I never had the courage to drain her though. She was always such a spunky little lady. She was a little over 5 years when she passed.

    • I had one with water belly, around two. I hate not knowing enough medically, as we began with chickens in 2016. I have Health Handbooks, which I find pretty much useless unless you know the condition! At any rate, I did have the presence of mind to drain her belly. Stuck a fresh hyperdermic needle after bathing her chicken butt, and my husband and I were amazed at the fluid. It was perhaps a little over a quart. She was Rhode Island Red. Her name was Diamond. She sat so still in a towel on the edge of my bathroom sink for this, as if it was a relief, which I’m sure it was. She was perked up so much I allowed myself a whisper of hope. Upon going back to “Sick Bay” in our house, she started scarfing down food like there was no tomorrow. Poor little girl couldn’t eat because the fluid contracted her stomach. She lived maybe six months, and then swelled up again and died in sick bay in my kitchen.
      I read somewhere chickens life as long as 13. Big fat lie. I have five of my original flock of twelve started in 2016. The first one to go was my favorite Black Orpington Queen chicken “Tanya.” I cried as if she were my dog. We would look into each other’s eyes deeply and quandry the meaning of life. Chickens that give you prolonged eye contact are more valuable than eggs.
      I too would love idea on how much flax seed to feed? What a cool thing to try and grow.

  4. I had chickens for 3 years, but ended up butchering them because when my father died we had to move back to our own house in the city. I had one hen that had a belly full of clear liquid, inside her I found 3 egg-size mustard yellow balls, these balls were free, not attached to anything. I have always wondered what they were and what caused them. I did some research but couldn’t come up with a definite answer. Reading this article, I’m thinking, could this be a cancer? We did not eat this hen.

  5. Thank you for such an informative article, Melissa. I’m pretty sure two of my girls recently died of ovarian cancer after reading your article. I suspected they were in some pain and allowed them to sleep in a nesting box for comfort. One has was the last of my original flock that I started with 7 years ago.

    • Oh Donna, my heart breaks for your girls. I know the feeling of losing them. I would have done the same thing with the nesting boxes. Comfort is so important. I’m glad that you were able to provide that. I also understand how special the original flock is. I still think about all of mine so fondly to this day.

  6. Melissa, I have a little Polish hen in my flock,probably about 6(unsure as I got her well after her egg-laying began). She tapered off on her egg production & it stopped completely. I assumed it was simply her age & didn’t mind since I view them as pets & obviously don’t eat them when they are done laying. She went 2 full years w/o laying any eggs, & suddenly began again this winter. I am confused as I have never experienced this in my 13 years of having chickens. I get about 2 a week, & the majority of them have a fair amount of bloody streaks on them. She seems fine in all other ways, but some kind of cancer was my first thought, especially since she had that 2 year period of not laying. I did get some new chickens and they started laying this summer. I know it sounds silly, but any chance their eggs would somehow affect her hormones?

    • Hi Cheryl, yes, I do believe that hormones do play a role. Also the quality of their feed also can affect their egg laying. The blood streaks are from laying larger eggs and those are usually benign. Chickens can also stop laying for a variety of reasons including stress, fear of predators, improper nutrition and as you mentioned age. Hope this all helps.

  7. Thank you for sharing your stories. I have Rhode Island Red “Meg” who is dying of cancer. She is 4 an half. I had her drained 3 times. treated her for infection but my vet told me it could be cancer. The second drain 600 cc, we knew she had cancer. She has been in my house for 5 months away from the other girls comfortable. I won’t do this again, draining. I know it’s cancer. It’s heart breaking. I have 7 layers now, 1 an 2 year olds barred rocks. Meg is the last one of my reds. They are dogs! Jump on my lap every time I sit in the pen. I read all the time about layers don’t live long. These girls have personality and give so much. I just love them more. Thanks for sharing

    • I’m so sorry that you are going through this Lori. I have said many times before that I wish chickens could live long lives, they become such a part of our families. I’m so sorry that Meg is experiencing this. Sending you a big hug and know that you and your flock are in my thoughts.

  8. Thank you so much for the information. I started with hens less than four years ago, with my three ladies. They are four years old. Cinnamon has just passed away. If you had asked me barely a month ago I’d told you she was full of beans, a lovely and friendly hen. She laid at least six eggs a week, fairly large and sometimes double yolkers too. She laid 3-4 eggs misshaped,and one without a shell, before she stopped completely for a month. Her mood also changed, she was a bit short-tempered at times, but sociable still. One day I found her sitting down all day, lethargic. It seemed to pass, but five days later there she was again. We took her to our local animal hospital were she was treated for four days. Apparently she had lumps inside her and plenty of fluids. Her breast bone was ever so prominent (we’d never noticed it) as she had lost a great deal of weight. Those feathers certainly did trick us. The vet decided to operate and then realised those lumps were all over the place. We decided to put her down on compassionate grounds there and then. The post mortem showed cancer of the oviduct, with metastasis to the ovaries, liver, spleen and bowels. It was a great relief to know that it wasn’t avian tuberculosis as we had feared. Now I’m down to two girls, both lovely in their own ways, unfortunately Cinnamon was the glue that stuck them together and they seem to spend time apart these days. I’ve resolved to keeps closer eye on them as hens seem to be ever so resilient brave little beings. Cinnamon must have been suffering for months and we hadn’t a clue!

    • Oh I am so very sorry to hear about your precious Cinnamon. This has happened to a few of my girls too. I know what you are going through and am sending you and your flock and family all the best for the ability to heal and find peace. I am glad to know that you still have more chickens and perhaps you can add to your flock one day again. Thank you for sharing your experience with us. It is helpful is so many ways.

  9. I’d like to see a study on this as to oyster shell, and heavy metals in oyster shell. It’s common sense that oyster shell should contain heavy metals, probably being farmed, but simply where even the wild ones live they should all contain bad things. I found a purer form of calcium supplement from Coyote Creek just to avoid oyster shell. I feed my girls the same filtered water I drink from a Zero Filter water pitcher, they have their very own. Organic feeds from Modesto, non corn and soy, organic treats as much as possible. My little ladies are only eight, (nine?..I’m losing my mind..!) weeks old, out in their big new coop and run. My very first flock, 15, oh, I’m sorry, I’m only allowed ten so I have..ten, wink wink, and being disabled from a Symphony career I have to say I was utterly in love the second I opened that tiny box in the post office and saw all those fluffy heads turn to me! Keep your girls happy, give them a treat today..my girls have organic Swiss chard and organic watermelon on tap for this afternoon!

    • Great food for thought! Thanks for mentioning this and now you have piqued my curiosity as well. I’ll be sure to get back if I learn anything. I love the story of your flock too. Sounds like you have some serious chicken math happening there. I think it’s the best kind of math out there.

  10. Thank you Melissa for your thoughts. We ara now worried about Whitey. She seems to have a protruding breast bone and a bloated belly, but we are not sure. We fear she might have stopped laying eggs for a few weeks now, and I’ve seen a few white and watery droppings that might be hers. The other day we spotted one of those empty and shell less eggs, shrivelled up and translucent. She is in good spirits and seemingly behaving as usual. It breaks my heart to think that she might be dying soon. It’d be so unfair. If that’s the case, I think I’ll be done with hens, unless I manage to find ex battery hens that I could adopt. I don’t think I want to eat eggs anymore knowing that all this suffering is being caused by human grief and disregard for animal welfare, as hens in the wild used to ovulate all but once a month (like female humans do).

    • Oh dear Tony, I am so very sorry. These situations are so difficult and heartbreaking. Please do share an update on Whitey. Maybe she just has a full crop? I hope that is the case. I’m thinking of you all.

  11. Thank you Melissa. Whitey has had her second Epsom salts soak. I’ve given her antibiotics for a week now. She seemed to be on the way to recovery but today she is looking tired and in low spirits. She even fell asleep in my arms after the bath. She goes to roost very early these days too. I’ve made up my mind to take her to our local clinic tomorrow morning, but I fear they might keep her and tell me there’s nothing we can do for her. It’d be incredible that two out of my small flock of three hens should develop ovarian cancer round about the same time. Really worried for our little darling!

    • Thank you for the update. I am so glad to know that Whitey has you there and you are able to tend to her needs. Good luck and let me know how things go for you.

  12. Whitey sadly passed away four days ago. I took her to our local clinic and after running a few tests we realised there was nothing we could do for her. Ovarian cancer again.

    Now it’s only Sonoko left. She is an Andalusian Blue, extremely shy. She is all alone now. I fear for her mental health. We are thinking of getting a couple of ex battery hens some time soon. Do you have any info/tips on how solitude can affect a chicken?

    Now I have made up my mind to never buy or consume third party eggs ever again. There’s so much cruelty in the egg industry (same as in the dairy Industry).

    We’ve watched a film on farm animals that we really loved and found very touching: Gunda. Have you heard of it? I totally recommend it!

    • Hello Tony, I am so sorry to hear about Whitey. It think getting Sonoko some friends and companions is a good idea. Chickens do best in flocks of 3 or more. Yes, being alone can take a toll on their mental health. You are right. I haven’t heard of the film but will check it out. Thanks for the tip and good luck.

  13. Hello Melissa, thank you for the very good report and for your research, and I have read the other comments with interest. I really do not know if Josie (2 years old) has cancer but I remember reading somewhere that clear fluid is a clue. She had a prolapse early May, which we have managed to keep under control, she often laid double yolkers, plus soft shell eggs and presumably this caused the prolapse. Now she has a very bad yeast infection. I obtained a prescription from our local vet (I live in France) and I am giving her 8ml of Mycostatine twice a day, which is no easy feat and I hide it in her favourite foods (once I checked they were okay with a yeast infection). My biggest worry is that she is dripping fluid constantly, it is like a faucet (I think that is how you say tap) has been left to drip. I have her in a cage in the house away from the other girls (she has also been bullied since the prolapse and has gone from number 2 in pecking order down to the bottom). She is the cutest girl, I bathe her every day and she just sits there happy for me to attend to her. I am sure the Mycostatine will clear the yeast infection (although we are now on day 4 and have a 7 day prescription, with no sign of it clearing), but it is this constant dripping that is so worrying. I have looked on various sites and cannot see any clear reference to it, although someone did say it might be a stuck shell less egg and to treat her with Calcium Citrate, which I did for 3 days but nothing appeared. You talk about fluid in the belly with cancer, could this be it? She has also started to walk funny recently. She lifts each foot in an exaggerated manner as though she is a ballet dancer, could this be connected to a tumor possibly? I really would appreciate any input you can give me as I just want to try and do my best for her, but if she is suffering then I will be sad to do it, but I will have her euthanized. Thanks in advance for your time and understanding.

    • Oh dear, I am so sorry that you are going through all of this. Goodness, it is so hard to know. You could try adding some probiotics to her water and also so vitamins and electrolytes That may help as well. Perhaps so plain unsweetened yogurt might help as well. I agree to keep bathing her as well. It’s hard to know exactly what is going on. She definitely could have a yeast infection and maybe cancer? But the ascites (in the belly) would not be leaking out the vent. Could there be an egg in there blocking it? Could she have an egg yolk peritonitis? What does the vet think?

  14. Thank you for this post Melissa, and for sharing your experiences and insight.
    Ive just come back from the vet where my little Jeannie has been put to sleep.
    Vet initially thought EYP but on reviewing her today, her abdomen was “very full”
    And she was struggling to walk. She was pretty certain a tumour was the cause.

    It was the wide gait that first alerted me a few weeks back. Not so much penguin stance. She looked like her thigh feathers were puffed out, but I think it was her actual legs that she was holding wider to accommodate her tummy.

    She was the cutest, most gentle hen. I’ll miss her dearly.

    • Oh no, I am so sorry. I am sending you a big hug. They have a way of wandering into our hearts. I’m grateful that you had one another. Thank you for sharing your experience. I am so sorry that she is gone but she is now at peace and painfree. XO

  15. I think one of my much loved hens has come down with this. Despite loving having hens over the last three years in my garden I’m now thinking that its not ethical to have these poor hens that have been breed to lay so often, resulting in cancer and a short life 🙁 Perhaps I’ll try and find a breed that lays at a more natural rate, as I really enjoy having hens around.


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Sharing an inspired life from the New England seaside. Chickens, Bees, Gardens, Art and Yummy Goodness.