Tag Archives: nitrogen

Is your dog killing your grass?

This is the time of year I get calls about the effectiveness of various products that are supposed to help prevent those brown lawn spots caused by dog urine.  Do they work?  Is it worth the money?  Is there anything else that can be done to stop the problem?

First, it is important to understand why those brown spots form where a dog urinates.  It isn’t due to the pH of the dog’s urine, but rather the amount of nitrogen in the urine.  Nitrogen is a break-down product of the protein in the diet and it is passed out of the body in both the urine and feces.   Nitrogen is also the main component in fertilizer.  So some nitrogen on the grass is a good thing, but if there is there is too much, then it will burn the grass, leaving that brown spot on your lawn.  But as the nitrogen diffuses into the soil, the concentration decreases and the grass becomes fertilized.  So you have a brown spot surrounded by fast growing, very green grass.lawn burn

It has been found that the volume and, especially, the concentration of the urine (and therefore the concentration of nitrogen) are the important factors in lawn burn.  Female dogs (or male dogs that squat, rather than lift their leg) are more likely to cause lawn burn.  Male dogs that lift their leg urinate smaller amounts and, generally, on a vertical surface, so the volume and amount of nitrogen deposited is much less (and often in areas where you wouldn’t notice killed grass). The pH of the urine (how acidic or basic it is) had no effect.

The various products marketed to help eliminate lawn burn when fed to your pet (or put in their water), don’t work.  They are designed to alter the urine pH, which isn’t the problem at all.  And altering the pH of the urine can predispose your pet to developing crystals in the urine, which can eventually form into bladder stones.

So what can you do?

The first thing to try is to dilute the urine.  Have your dog drink more water each day. Feed at least some of the daily calories as canned food or add water to the dry food.  Make the water bowl more interestidrinking dogng by adding some ice cubes.  Have multiple water bowls throughout the house.  Have one water bowl with flavored water–a little chicken broth or beef broth added to the water can make it more enticing.

You can also feed your dog a food lower in protein, which will decrease the nitrogen in the urine.  Most dogs (except for very energetic, working breeds) don’t need nearly as much protein as is found in most dog foods.  (This also explains why so many dogs are overweight.  But that is a topic for another blog!)  It can be very difficult to read pet food labels as the %  protein doesn’t really tell you much by itself.  But it is a place to start.  A diet with high quality proteins are also more digestible, so less protein (and therefore nitrogen) is dumped into the urine.  Premium pet foods tend to have more digestible proteins than foods from the grocery store.

As far as the lawn, diluting the urine immediately after your dog squats can help.  Carry a water bottle with you and dump the water on the spot right away.  Train your dog to eliminate in a designated area, ideally one landscaped with pea gravel or mulch.  It has been found that fescue and perennial rye grass are the most resistant to lawn burn, while Kentucky bluegrass and Bermuda grass is the most sensitive.  So if you are reseeding your lawn, choose fescue!  I’m guessing dandelions and crab grass are pretty resistant, too…

One final note: if your dog has been causing lawn burn and suddenly isn’t, and you haven’t changed anything, you should have a urine sample checked and some blood taken.  Your pet may suddenly be drinking more, diluting the urine, which can indicate underlying diseases.

Here’s to a great, green-lawn summer!