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Yes, Dog Pee does Kill Trees

November 29, 2010

Enjoying a tree-lined street in Washington Square with Ginger

Most urban dwellers love the look of trees in a city.  Trees not only add real estate values to our neighborhoods, they cool our homes in the summer and make our city an aestheticly beautiful place where we can live happy and healthy lives under their oxygen-giving leaves. The beauty of a tree lined street attracts new businesses to vibrant shopping corridors and define entire neighborhoods. Numerous studies have shown that trees in proximity to neighborhoods even make people who live there happier – quantifiable.  (Do you want a tree planted in front of your house for free?  It’s simple, fill out an application.)

As a “mom” to two city-living dogs (and owner of a large dog walking service in Philadelphia), I also happen to be a graduate of Pennsylvania Horticultural Society’s Tree Tenders program.  It’s safe to say I love dogs AND trees.  I hear the same question a lot, “Does dog urine really kill trees?”  Unfortunately (for the dogs and the trees), yes.  Dog urine kills trees.  There is no doubt about it.  Let’s learn more about tree botany and what you can do to save the trees in your neighborhood and how to be a responsible dog owner.

The bark is actually peeling back from the acid burn. This tree likely will not survive.

How Urine Kills Trees: Urine is highly acidic.  Simply put, dogs’ urine “burns” the tree’s trunk to the point that the tree becomes susceptible to diseases, pests, dehydration and nutrient loss.  The bark is a tree’s protective barrier.  Repeated hits with urine basically causes an “open wound” right on the base on the tree.  Since the bombardment from pee is semi-constant in an urban environment, the trees never have a chance to heal from past damage.  These wounds open the trees up to a slew of diseases that they just can’t fight off.  (Female dogs do just as much harm even if they aren’t “hitting the trunk.”  Repeated hits of urine in the soil will change the soil’s pH and kill the tree via the roots.)

The next time you go for a walk, take a look at the trees in the city and look around the base of the tree.  Many of them show signs of deep fissures in the bark 2 feet up from the ground, cracks along the trunk and some even show signs of bark literally peeling back just above the ground.  Others are literally bleached white from urine.  (Check the next time you go for a walk.  Most of the damage is in the lower 2 feet of the trunk.  If you’re a tree-lover, you might start to panic.  Try not to panic, we’re trying to raise awareness!)

Bleaching and bark fissures shown. Note all of the damage is in the lower 1.5ft of the tree trunk.

It’s easy to think, “Surely a little pee from my dog can’t do harm to a huge tree.”  Think about it like this.  Your dog “marks” the tree, then another dog walks by 10 minutes later, smells your dog’s scent and hits it again, 15 minutes later and another dog walks by, hits it again.  This goes on day in and day out, 365 days a year.  Some trees are hit more than others and a cycle begins.  One dog’s scent ends up on a tree and others just keep marking it, over and over until the tree is compromised.  (Compare our urban trees to those in a healthy forest, where one might get peed on once every few weeks by a randomly passing hiking dog…  Our trees are hit multiple times, daily.)

Saplings are the most vulnerable, but plenty of really old trees in the city are showing signs of urine poisoning too.  What can you do to help?  It’s simple.  Redirect your dog when he/she is headed for a tree.  Teach your dog to “curb it.”

It’s easy to think that when you see an angry sign posted on a tree that says, “NO DOGS!!!!!!!!!!!” that the person is just anti-dog.  Perhaps they’re just pro-tree?  As urban dwelling dog parents, we have to always remember that we have to share our urban space with other folks.  Some like dogs.  Some don’t.  Some might like dogs, but also like their tree out front. Regardless of their preference toward our furry friends, if we, as responsible dog owners, do our part to be great neighbors – we make our city a better place.

Stay tuned for articles in the next few days on:

Wondering how to teach your dog to “Curb It?”  We’ll tell you.

Have a tree out front that you want to protect?  We’ll tell you how to do it.

We love Philly.  We love dogs.  We love trees.

(All of the photos taken shows were taken in 2 square blocks in Bella Vista, within a three minute walk of each other.)

A young sapling, fissures starting to show.

Acid Bleaching. This tree in bad shape.

6 Comments leave one →
  1. fiery permalink
    February 20, 2011 6:15 am

    WOW! That was a really well written, helpful post. Thanks for that! :D

  2. April 21, 2011 6:10 pm

    SO, can you “revive” a young tree after this has happened? Only started with my dog in our front yard last Summer, and the tree never really bloomed… it also doesn’t have any buds on it yet this Spring : ( is it dead forever?!


  3. carolyn duffy permalink
    July 25, 2011 3:53 pm

    Hello, I would like permission to reprint all or part of your article, Yes, Dog pee does kill trees.

  4. July 27, 2011 6:08 pm

    Thank you for the info and the pictures to back up the fact that dog urine kills trees. At the Frostburg Dog Park, our trees are on the outside of the park just for this reason. We love our dogs and our trees too!

  5. Bill Crumlic permalink
    August 8, 2011 2:04 pm

    I really appreciate this article! I live in NYC and someone several doors away started yelling at me when I was walking my four Jack Russells this morning. We stopped at a tree well for them to pee. To be clear they did not pee on the tree trunk but near the edges of the well (three small girls and a boy) so I did not see an issue. I knew peeing on the trunk could cause damage so I trained them to not pee on uprights. I reacted rather poorly as someone yelling from up the street is embarrassing so I am afraid I was defensive and rather rude with the boisterous woman and told her to call the city if she had an issue along and to mind he own &*%$ business. Now that I have read this article and see that the pee can change the pH in the surrounding soil I will wait until we get to the park for them to pee. I will also apologize to the woman when I see her and explain calling someone out on something can go much better if she approaches them and speaks as an adult rather than shout loud curses up the street. I did not nurse Hitler for crying out loud! Hopefully it will be a lesson learned for BOTH of us.


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