Does Marek's cause reproductive cancer?

[SarahGfa]

I lost 3 out of 5 leghorns to ovarian cancer this year. Two were diagnosed by an avian vet and euthanized after months of supportive care. Third one filled with fluid and died before I could treat her. Now my 4th hen is showing the same symptoms (stopped laying, bloated belly).

Could this be caused by Marek's? The hens were between 2 and 3 years old. It is not normal for hens to die this young. They all came from the same hatchery.
Has anyone else experienced such high occurrence of ovarian cancer in a young flock?

 

[Eggcessive]

I am not an expert on Mareks or tumors in chickens, but Mareks disease causes lymphoma cancer. Oviduct tumors are usually adenocarcinomas, and are common after the age of two. A third type of tumors in chickens is squamous cell carcinoma which can occur in other parts of the body. So I would say that if you have gotten a necropsy that shows oviduct cancer, it is probably not caused by Mareks disease.
http://www.poultrydvm.com/condition/cancer

 

[SarahGfa]

I am not an expert on Mareks or tumors in chickens, but Mareks disease causes lymphoma cancer. Oviduct tumors are usually adenocarcinomas, and are common after the age of two. A third type of tumors in chickens is squamous cell carcinoma which can occur in other parts of the body. So I would say that if you have gotten a necropsy that shows oviduct cancer, it is probably not caused by Mareks disease.
http://www.poultrydvm.com/condition/cancer

Thank you for the good information. I didnt know there were different types of tumors. You sound like an expert

If oviduct tumors are common, how do so many hens survive to 5-8 years old? Are there breeds that are more resistant to cancer? Could it be related to diet?

 

[coach723]

Fat birds are more likely to have all kinds of health problems, so if they are on a diet that makes them fat, then yes, it can contribute. Some birds seem to be genetically predisposed to fat deposits in the abdomen, so diet is not always to blame. Some birds do live long lives. My most healthy ones have been heritage breed birds, that have not been bred specifically for heavy laying, and some mixes, like Easter Eggers. But even those can have problems sometimes. When you have a reproductive system that ovulates every day, or nearly every day, then problems can happen. In humans, a female ovulates once about every 30 days (rounding for convenience of math), so say from age 15 (again rounding) to age 55, at that rate a human would ovulate approximately 480 times. That's in 40 years. A hen would ovulate 730 times in 2 years, if she's laying every day. So you can see that the oviduct is working really hard, and the likely hood of a problem is increased. Just like in humans, not all cancers can be predicted, every immune system is different, every genetic code is different. I had a 9 year old bird that hadn't laid in several years, and I still lost her to a abscessed ovary.
Non-production leghorns are considered a heritage breed, production leghorns are not. Most birds in backyard flocks are going to be the production birds. For the most part, large hatchery's are going to be selling 'production' birds. For a true heritage bird most often they will be gotten from breeders whose only focus is breeding to meet the standard for that breed. That doesn't mean you can't or won't get nice birds from a hatchery, just that they may not live as long and may have a higher percentage of problems over all.
A couple of articles:
https://livestockconservancy.org/index.php/heritage/internal/leghorn
https://justfowlingaround.weebly.com/breed-profiles/white-leghornheritage-breed