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.
Ovarian Cancer in Backyard Chickens: Risk Factors
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.
- Consider purchase of breeds that are not heavy egg layers.
- Allow hens a natural break in the winter from laying eggs.
- Omit artificial lighting in the chicken coop to stimulate egg laying.
- Allow hens to go broody because this also allows for an egg laying rest period.
- Consider adding flax seed to their diet.
- Consider restricting their caloric intake. (Approximately 1/4 cup chicken feed per day/hen)
- Consider feeding your flock a soy-free alternative.
- Explore alternative protein sources for your flock other than soybeans.
- 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.
- 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).
- Likewise, increase free-ranging your flock to diversity and supplement their diet.
- Furthermore, share this information with fellow chicken keepers.
Please know that this post is intended for informational purposes only and does not substitute for advice from a licensed veterinarian.