Dog pee plea

The red maple in Brown’s Inlet near the corner of Craig and Holmwood shows signs of damage from acidic dog pee. Photo: Joan Forbes

By Carol MacLeod

In late September, I took a walk through Brown’s Inlet Park. Just five years ago, Virginia Carver and I, then co-chairs of the Glebe Community Association’s environment committee, had spearheaded a “BioBlitz” in the park. At that time, we noted that many trees were beginning to show the effects of concentrated dog pee at the base of their trunks. I’d taken a Jane’s Walk earlier this spring and noted then that trees along the pond were showing signs of stress. On my most recent visit, the damage had progressed to the point that several trees were dying.

Doggy doo done

Pet owners have embraced the “stoop and scoop” message. Responsible dog owners wouldn’t dream of leaving feces on neighbours’ lawns, local sidewalks or in parks.

Urine for it!

Now it’s time to take the next step and train dogs to pee at the curb. Why, you ask, do we need to do that? All dog pee is acidic. Depending on its sex and what a dog is fed, that acid can be more concentrated. We know that dog pee leaves rings on our lawns. The dead centre is surrounded by a ring of bright green, very healthy grass. That’s because, although grass loves some nitrogen, too much of a good thing kills it. Concentrated dog pee alters the soil so that it becomes impervious to rain.

When pee meets tree

The same thing happens to trees. If you look at the sidewalk side of trees along our streets, particularly those on the way to parks, you’ll see that the bottom three feet adjacent to the sidewalk is whitish. Telephone poles share the white look. That’s the effect of acid on wood. Dog pee seeps through the bark to the cambium, the inner-growth layer of the tree. Over time, the bark peels back, exposing that growing layer. Then ants and other insects invade. Woodpeckers soon find the new food source. By then, it’s too late to save the tree. A classic example of this progression is the red maple at the Craig and Holmwood entrance to Brown’s Inlet park.

The last weeks of September were discouraging ones for the environment. A study showed North America had lost three billion songbirds in five decades. The latest reports by the International Panel on Climate Change tell us climate is changing much faster than our original models suggested. Temperatures in Canada are rising at about twice the predicted rate. Greta Thunberg eloquently reminded us that to leave a habitable world for our kids, we have a decade at most to slow things down. Climate change marches across the country showed that people do care about the environment. Politicians promised to plant two billion trees in the next 10 years – too little and perhaps too late?

Since trees take so long to grow, why not steward the ones we have? The trees the city plants are about 15 years old. The best information I can find suggests each tree costs at least $350 to plant. Protective cages, like those surrounding street trees, may cost an additional $400 each. So why don’t we do more to protect our existing investment in urban trees?


We can protect newly planted trees with surrounds designed to keep dog pee at bay. Such a surround was installed on the tree in the St. Giles Church street parkette. A common garden fence about three feet tall permanently installed to make a two-foot ring around the the tree trunk would serve equally well. The Central Experimental Farm has had some success placing three metal T-posts about four feet away from the tree so they become pee posts.

But the most effective action is to make sure dogs don’t pee on or near the tree trunk.

Cities across North America have taken steps to protect urban trees. For example, a couple of years ago, condo owners near a city parkette in Toronto took concrete measures to save the park where they walked their dogs. It was under mortal stress from the concentration of dog pee. The newly landscaped park has a special path designed for peeing and a sprinkler system designed to wash the pee into the storm sewer for treatment. See the CBC report on the park at

Now, if we could only convince the city to install segregated bins for dog waste in our parks!

Carol MacLeod is chair of the Glebe Community Association Membership Committee, former co-chair of its Environment Committee, and an avid gardener and nature enthusiast.

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