This time of year, a killer lurks in ponds and some slow-moving bodies of water that can kill your dog with just a few gulps.

The wide blue sky, light winds and warm days are a recipe to produce blue-green algae blooms on ponds, lakes and some backwaters of rivers and streams. The algae tend to float on the surface and can collect on the downwind bank. The naturally occurring microorganisms can produce deadly toxins that can kill even when moderate quantities are ingested. If the wind doesn’t create a lot of wind action, the toxins increase in concentration, too.

People who hunt with dogs for upland game birds have had this knowledge for a long time. Their seasons usually start early when the weather remains warm. The dogs are eager for the new hunting year and run a lot. Twenty-five to 35 miles a day per dog is not uncommon. Hunters pack along water for their dogs even though it weighs about 8.5 pounds per gallon. They do not wait to find water they think will be safe and they do not assume they will be back to the truck before the dogs get thirsty.

The fact is, most people who enjoy outdoor activities like hunting don’t keep themselves well hydrated during the day, much less their dogs or horses. For optimum performance of all parties, hydration must be a priority. More than 35 years ago I read a great, peer-reviewed paper consolidating research funded by the dairy industry on the value of water, not only in cows but in humans and on human performance as well.

Most people have some idea about how bad it is to be severely dehydrated. At the same time most people have no idea how much even mild dehydration affects human performance. For example, the science is clear that dehydration drastically affects visual perception by the brain. According to research published by Grandjean and Grandjean, in 2007, psychomotor and cognitive performance declines can occur when only 2 percent or more of the body weight is lost because of water restriction, heat or physical activity.

Scientific literature concerning physical performance and hydration stretches back all the way to the late 1800s. The consensus is clear, even mild dehydration can stimulate inhibiting alterations in central nervous system activity. This means people, and probably dogs too, display reduced motivation and effort. Heart function and metabolic reactions are affected, and so is the ability to control body temperature.

Again, a water loss, exceeding 2 percent of body weight (about a half-gallon in a 200-pound person or a quart in hard-charging bird dog) can begin this level of impairment. As for body temperature, sound hydration is also important in winter months, although the effects are more severe and occur more rapidly in hot environments.

So why do we overlook just plain water? Well in a word, water’s taste can be boring compared to so-called “thirst alternatives.” Still, regardless of the amped-up formulation, the main component in all such drinks is water and most experts say if it gets one to consume more fluids, that is a good thing.

Currently a new line of “dog beverages” is being introduced, and while I haven’t seen any performance claims so far, I’m sure they’ll come in future advertising. In the meantime, remember your dog and your body evolved to drink water, just plain old water. With rare exceptions, it remains the cheapest and most available performance enhancing nutrient.

Drink up!

Charlie Powell is the public information officer for the Washington State University College of Veterinary Medicine, which provides this column as a community service.

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