March 1, 2008

Rottweilers, bone cancer and mandatory spay/neuter laws

Got a slew of posts to add, and I hate to start with such a sad one. It's important, though. I'll make the message as clear as I can:

Male and female Rottweilers spayed/neutered before 1 year of age have an approximate one in four lifetime risk for bone sarcoma and are significantly more likely to develop bone sarcoma than dogs that are sexually intact.

See this link for the abstract at PubMed. See this link for the complete study. From the abstract:
Endogenous gonadal hormone exposure and bone sarcoma risk.
Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters DJ.
Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, Indiana 47907, USA.

Risk for bone sarcoma was significantly influenced by age at gonadectomy. Male and female dogs that underwent gonadectomy before 1 year of age had an approximate one in four lifetime risk for bone sarcoma and were significantly more likely to develop bone sarcoma than dogs that were sexually intact [RR +/-95% CI = 3.8 (1.5-9.2) for males; RR +/-95% CI = 3.1 (1.1-8.3) for females]. Chi(2) test for trend showed a highly significant inverse dose-response relationship between duration of lifetime gonadal exposure and incidence rate of bone sarcoma (P = 0.008 for males, P = 0.006 for females). This association was independent of adult height or body weight.
And no, it isn't just Rottweilers. From the essential report on spay/neuter health effects, by Laura Sanborn:
Osteosarcoma (Bone Cancer)

A multi-breed case-control study of the risk factors for osteosarcoma found that spay/neutered dogs (males or females) had twice the risk of developing osteosarcoma as did intact dogs[13].

This risk was further studied in Rottweilers, a breed with a relatively high risk of osteosarcoma. This retrospective cohort study broke the risk down by age at spay/neuter, and found that the elevated risk of osteosarcoma is associated with spay/neuter of young dogs[14]. Rottweilers spayed/neutered before one year of age were 3.8 (males) or 3.1 (females) times more likely to develop osteosarcoma than intact dogs. Indeed, the combination of breed risk and early spay/neuter meant that Rottweilers spayed/neutered before one year of age had a 28.4% (males) and 25.1% (females) risk of developing osteosarcoma. These results are consistent with the earlier multi-breed study[13] but have an advantage of assessing risk as a function of age at neuter. A logical conclusion derived from combining the findings of these two studies is that spay/neuter of dogs before 1 year of age is associated with a significantly increased risk of osteosarcoma.

The researchers suggest a cause-and-effect relationship, as sex hormones are known to influence the maintenance of skeletal structure and mass, and also because their findings showed an inverse relationship between time of exposure to sex hormones and risk of osteosarcoma.[14]

The risk of osteosarcoma increases with increasing breed size and especially height[13]. It is a common cause of death in medium/large, large, and giant breeds. Osteosarcoma is the third most common cause of death in Golden Retrievers[10] and is even more common in larger breeds[13].

Given the poor prognosis of osteosarcoma and its frequency in many breeds, spay/neuter of immature dogs in the medium/large, large, and giant breeds is apparently associated with a significant and elevated risk of death due to osteosarcoma.
Yes, Laura Sanborn is a leader in the fight against mandatory spay/neuter. Her review of the literature is evenhanded — quite the contrast with California's AB 1634 supporters, who are past masters at misinterpreting [I'm being kind, here] all types of data. And no, there is simply no way to spin the science and come up with anything that makes osteosarcoma appear less of a risk for medium size or larger dogs subjected to early spay/neuter.

If you support mandatory spay/neuter laws like AB 1634 or the recently passed spay/neuter law in the city of Los Angeles, you are apparently willing to condemn many dogs to an agonizing disease and a drastically shortened life on the entirely baseless speculation that this might somehow help reduce the number of dogs and cats in animal shelters.

God forbid individual citizens should make medical decisions based on what's best for individual animals — right, Lloyd Levine? Tell us again how your determination to mandate a dramatically increased risk of canine osteosarcoma is really no different from telling people to buckle their seat belts.

Related links:
Heartbreaking message posted in the Border Collie Boards In Memoriam section.
Dolittler post on amputation for dogs suffering from osteosarcoma. Nothing said about whether the Rottie was neutered — I'll ask.
Rottweiler Health Foundation.


Anonymous said...

I'm so glad I'm not the only one! I'd also done a great deal of research into the topic some time ago; unfortunately I did it to sate my own curiosity and failed to keep my sources once I'd drawn my own conclusions.

I consider alteration to be the "lesser evil" to unwanted animals winding up in shelters and eventually being euthanized. But there's good reason for supporting less drastic population control methods such as vasectomies in some situations, or at least permitting an animal to reach maturity before undergoing alteration.

The goal of vet med should be to improve the quality of life of animals--not only in terms of addressing the problem of unwanted pets, an issue which concerns me greatly, but also the lives of cherished pets. How to give both sides consideration needs more open dialog than the stock arguments bandied about currently.


So glad to read your post. Also, it is important to know that there is the option of a partial spay for female dogs, where the ovaries are left intact. Essentially, the dog is just having a hysterectomy, so that she won't be able to conceive, and won't spot, but will still have that essential hormonal influence. There is also a new study published in 2009 in the journal AGING CELL, that suggests spaying a dog decreases their lifespan by 30%!!!

Anonymous said...

My lovely adopted Rotti mix female, was spayed before I got her. We spent her too short life dealing with 2 CCL/rear knee ligament tears (NO TPLO for us!) She had a few good years and then osteosarcoma struck. Ofcourse I did not put her thru any additional suffering. I gave her a good life, but let her go....

Now I have an adopted 2 year old Female Lab mix... and have not spayed her yet. In my heart, I am waiting for Vets around here to do Ovary sparing spays.

I love ALL DOGS, they are humanity's greatest gift.I also know what goes on in kill shelters (PLEASE ADOPT, don't SHOP). The ONLY way to go is vasectomy, and Ovary-sparing spay!

Anonymous said...

There are a few problems though. There are health related issues with intact animals namely breast cancer in females and testicular cancer and prostatitis in males. Also, many pet owners are not equipped to deal with hormonally intact animals.

Anonymous said...

Indeed, there are health issues with intact animals, but mammary/testicular cancer are generally operable and have a relatively slow progression. A good vet will routinely check intact animals for these cancers. Incidence of pyometra is breed-dependent. Mortality with treatment is 3% to 4%. In contrast, treatments for osteosarcoma can slow the disease's progression, but the disease itself is typically fatal in short order. Neutering also increases the incidence of spay incontinence, separation anxiety, noise phobia and orthopedic injuries. True, many pet owners are not prepared to deal with intact animals. That said, a typical b itch may be in standing heat for 7 days, twice a year. Even if said b itch roamed free every day of the year, she would only be at risk of accidental breeding 14/365 = 3.8% of the time. Many families are perfectly able to supervise an intact pet, so the risk of unwanted pups is not a rationale for systematic neutering of every pet dog.