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Do Environmental Pollutants Cause Cancer in Dogs?
Do environmental pollutants cause canine cancer?


From the pesticides used in agriculture, insecticides and cleaners used in households, and solvents used in paints to toys made of synthetic products and artificial preservatives and additives in our food, man-made chemicals and pollutants are everywhere. With so many synthetic chemicals around us, could some of these products—as well as other aspects of our environment—be causing cancer in our canine companions?

Dr. Larry Glickman, veterinarian and epidemiologist at Purdue University, has no doubt that they do. “Of course. There are many chemicals and environmental factors known to cause cancer in people, and many may also cause cancer in pets. The problem,” he observes, “is that these are far better studied in humans than in pets.”

The dearth of study is a matter of both convenience and money. Says Glickman, “With humans, there are mandatory reporting systems for disease—such as death certificates, [which list the] immediate and underlying cause of death.” As a result, agencies can track how frequently certain diseases result in death, and thereby accumulate information as to whether there is an increase or decrease in specific cancers, for example. “With animals, we don’t have anything,” say Glickman. “We just have scattered pieces of data to look at frequency of diseases.” These include hospital records or, increasingly, insurance claim records. But, Glickman emphasizes, “This is way behind what has been done in humans.”

Clear Links Exist
Despite the scarcity of studies, some research has identified clear links between cancer in dogs and environmental factors. For instance, a 1983 study by Glickman and his colleagues revealed that dogs with a mesotheliomas (a rare tumor of the chest cavity) were more likely to have lived in households where owners had exposure to asbestos, or to have gone with their owners to workplaces in which asbestos materials were handled (e.g., shipbuilding and brake repair). Additionally, chrysolite asbestos fibers were found in significantly higher amounts in the lung tissue of these dogs than in dogs with other types of lung tumors and no history of exposure to asbestos.

In another example, Glickman notes that “exposure to cigarette smoke has been shown to increase nasal cancer in dogs.” Long-nosed dogs are two times more likely to develop nasal cancer if they live with a smoker than if they are not exposed to cigarette smoke, and the incidence of canine nasal cancer increases with the number of packs the human in the household smokes per day. Similarly, short-nosed dogs are twice as likely to develop lung cancer if they live in a house with cigarette smokers. In these dogs, cotinine levels (a metabolite of nicotine) in the urine are high compared to those of dogs in nonsmoking households. Taken together, these findings suggest that the longer air-filtration system of long-nosed dogs serves to protect them from lung cancer but also predisposes them to developing nasal cancer.

Glickman’s own research has revealed other environmental risks. As he reported in 1989 in the Journal of the American Veterinary Medical Association, female dogs exposed to insecticides in flea sprays and dips are at higher risk of developing bladder cancer than those on whom such products are not used. As with nicotine, the compounds in dips and sprays are absorbed into the bloodstream. The body gets rid of these products by excreting them into the urine. The risk is further enhanced in overweight females, most likely because the compounds, once absorbed, are retained in fat. Animals with more fat retain more of the chemicals. And finally, risk was also elevated in females who lived close to a second potential source of insecticides—a marsh that had been sprayed for control of mosquitoes, for example.




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Submitted by Dwight | January 31 2010 |

I'm a graduate of Ashland University with degrees in science and secondary education. One of my former professors, Dr. Weidenhamer, has made national news due to his research of childrens' toys and jewelry and presence of high levels of lead and cadmium contained within them. The biggest dangers occurs when the children have prolonged exposure to the lead and smaller children putting the toys in their mouth. Many of the toys that have shown extremely high levels of lead are ones made overseas (mostly China). Here's a link that about this: (http://personal.ashland.edu/~jweiden/lead.htm) and (http://blogs.consumerreports.org/safety/2009/09/lead-levels-in-childrens...).

My wife and I rescued a black lab mix dog. He goes through a lot of chew toys. While at the store, I noticed many of the toys we get for our dog also comes from overseas (ie. China). I've even come across some toys that are exactly the same as what's found at children's toy stores.

This got me to thinking. Should pet owners also be concerned of the possibility of lead in their pet toys? Has there been any research of the effects of lead in pets (dogs)? Since dogs tend to do a lot more of putting things in their mouth, chewing, and swallowing small amounts of chewed up plastic, what are the dangers of lead poisoning of our pets?

I've emailed my professor, Dr. Weidenhamer, regarding the testing of pet toys. He stated that some of the soft plastics used in pet toys are also used in physical therapy for people. Due to the large number of children's toys and general public's concern of their children, he doesn't have the time to test the pet toys.

We love our dog. He's an important part of our family. I know many others feel the same way about their dog(s). From going to the store the other day and seeing bottled water for dogs (which personally, I think is over the top), I know many people want the best for their dog...to be happy, healthy, loved, and well cared for. I feel that this is something that should also be looked into. Out of our love, I don't want to be an irresponsible pet owner and get something that could potentially be harmful for our dog. There are days that I believe our dog doesn't have too many IQ points to spare...he can't afford to lose anymore. (just kidding, he is pretty smart) Seriously, I think as a responsible pet owner, we need to speak on their behalf as to the hidden potential dangers of lead contained within pet toys.

So now, whenever we do get him some toys, I check the labels as to where they were made. It's not a guarantee, but hopefully it's a step in the right direction of keeping our beloved dog healthy.

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