You can’t blame pet owners for taking a few precautions. After all, pet food recalls raised concerns about chemical contamination; even treats have been scrutinized.
So, should we resort to bottled water for our canine companions? According to a study in the June 1, 2008, Journal of the American Veterinary Medical Association, that won’t be necessary. Tap water, the study suggests, doesn’t cause bladder cancer in dogs.
Long-term consumption of disinfected tap water – the stuff that flows from our faucets after being treated with chemicals such as chlorine – has been associated with bladder cancer in humans. But the study, which was led by Dr. Lorraine Backer of the Centers for Disease Control and Prevention, found that there is no such association in dogs.
There may be more than one reason why dogs that drink tap water don’t have an increased risk of bladder cancer, even though people apparently do.
First, a dog’s exposure to drinking water disinfection by-products – the chemicals that are produced when substances like chlorine interact with natural organic matter – is different from that of its human owners. Dogs don’t gulp down a big glass of water like people often do. Their water usually sits in a bowl for hours, which allows the chemical concentrations to decrease over time.
Secondly, dogs don’t take long showers or baths like people do. And showering and bathing are important routes of human exposure to chemical by-products of tap water.
The study focused on 200 dogs living in residential settings, 100 of which had bladder cancer and 100 that did not. While the results showed that dogs with bladder cancer were exposed to higher total chemical by-product concentrations than the control dogs, the difference wasn’t significant enough to draw a connection between tap water consumption and bladder cancer in dogs.