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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Bladder and Prostate Cancer: Neutering Male Dogs Increases Risk

Updated: March 23rd, 2020

Oh man. This is going to make a lot of people in my field angry.  Apologies to classmates and veterinarian friends!

I came upon a study from the August, 2007 journal Prostate.  Probably not what a lot of us would be reading in our spare time, but I am busy with upcoming info products for dog cancer owners and I dig through lots of publications.

The short story is the following:

Data was gathered from North American Veterinary Hospitals on male dogs that had been neutered (testicles surgically removed, or castrated), to evaluate the trend that had been noted in some older articles that neutering increased prostate cancer.

Because if this were the case (and this is my comment, not the authors’), it would seem ethics demand that owners of male dogs were advised of this before consenting to neutering surgery.

Here is what they found.  Hold your hats, folks:

1. Castration of dogs increases total malignant prostate cancer by EIGHT times for some prostate cancers (prostate adenocarcinoma). So the answer is yes, castration does increase prostate cancer in dogs (which goes against what I was taught).

2. Castration of dogs increases the most common type of bladder cancer (transitional cell carcinoma) by about FOUR TIMES.  This is huge!!  Major, major, industry shaking information as far as I can tell.

Okay, the pundit gallery will argue, but castration helps control the unwanted dog population, helps unwanted behaviors like aggression and territorial urination in undesirable locations, etc.  Yes, yes, all true.

But, we must start informing owners of this, to use Al Gore’s phrase, inconvenient truth.

And that is one of the purposes of this blog!

Best to all,

Dr Dressler


Leave a Comment

  1. Ann on July 3, 2021 at 12:45 pm

    Hi, My 14 years old miniature schnauzer girl got her X-ray done last week and was diagnosed with TCC. I felt like there is a big rock sitting on my heart. I have scheduled an appointment to see an oncologist but it’s 3 weeks away. In the meantime, what can I do to help her to increase her chances? She has history of pancreatitis but it’s under control for the past 3 years. I want to follow your receipts to give her better diet. I already gave her filtered water, vegetables, salmon oil, and organic chicken on the daily bases, but still mix it with a little low fat commercial dog food(4-5 stars according to the help me. Thank you in the advance. Ann

  2. Hideaki Saito on February 19, 2021 at 9:00 pm

    According to the Dog Cancer News dated Mar.20,2020, Castration of dogs increases total malignant prostate cancer by EIGHT times.
    My friend is planning to have her dog castrated during this month. It is seven months old.
    Even in Japan, some doctors estimate that the castration of the dog less than six months old has more risks to take prostate cancer. Does the period of castrations have anything to do with the possibility of prostate cancer. In fact I don’t really agree with the castrations, if the castrations influence the possibility, because different from human beings, I heard it is very difficult to find a prostate cancer in the dog.

    • Molly Jacobson on February 21, 2021 at 2:30 pm

      Dr. Dressler recommends waiting until 18 months to neuter a dog. That allows the adult hormones to do their job and protect the body. It doesn’t mean that the dog will NEVER get cancer, but it decreases the risk.

  3. Karyn on March 22, 2020 at 7:17 pm

    This is contrary to what I was taught (albeit I’m getting little long in tooth since my DVM) so I find this unsettling as for years I’ve told people just the opposite while recommending neutering; that it would almost negate the possibility of prostate cancer if neutered before 6 mons of age. I’m wondering if the very early neutering as is common in humane society puppies itesults in an even greater risk?

  4. Scott Jones on September 10, 2019 at 10:02 am

    My boy is not well and he was neutered as a puppy. All of my dog’s growing up were intact and they lived long lives. My dog is almost 10 and everything looks like prostate cancer at this point. Still waiting on the results of some testing but I don’t think I’d choose to “fix” another dog. This goes against nature and there must be some hormones that are naturally produced that are missing from these guys. Thanks for your honesty here. Its very important to share.

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