This article originally appeared in AKC Family Dog. No portion of this article may be reproduced without permission of the copyright holder. Reprinted with permission. Jeff Grognet is a practicing veterinarian in Qualicum Beach, BC, Canada combining traditional medicine, acupuncture, and VOM. He writes extensively for pet publications and also teaches online courses for Veterinary Assistants (www.ed2go.com – click on “course catalog”, then “veterinary”).
Some veterinarians call urine "liquid gold" because it has incalculable value in determining a dog's health status. But puppy owners who have to clean it up call it a waste product. For people who take pride in their lawns, dog urine is a nuisance that wreaks havoc on their pristine green carpets, creating yellow "scalded" spots in the grass. As spring turns to summer and landscapes fill out, some people become so upset by grass scalding that they refuse to allow their dogs to have access to their beautifully manicured lawns.Grass scalding from urine is almost entirely a female-dog problem. Males urinate in little squirts here and there, and usually not in the middle of the lawn. But females rend to urinate large amounts in one spot. To minimize urine damage to grass, it is important to understand the factors that affect it. The first is the makeup of the dog's urine itself. The second is the natural resistance of the grass and soil to the effects of urine.
Urine has three main characteristics that influence the damage it can cause to grass-acidity or alkalinity (pH), nitrogen content, and salinity. Urine phi is dictated by a dog's metabolism. Typically, canine urine is slightly acidic-it has a low pH-but the dog's diet can affect this. For example, vinegar is acidic and adding it to a dog's food makes her body more acidic. She responds by eliminating the excess acid in her urine, thereby lowering the urine's pH even further. Baking soda has the opposite effect: It is alkaline by nature, so adding it to a dog's food raises the pH of her urine.
Some folk remedies for preventing yellow, scalded spots in the grass involve adding mildly acidic substances such as tomato juice, vitamin C, or apple cider vinegar to a dog's food. These additives are seldom, if ever, effective. Despite common beliefs, changing the pH of a dog's urine has a very limited effect on lawn health. Also, after a short while on one of these supplements, the dog's body adjusts and brings the urine's pH back into the normal range.
It is the nitrogen content in the dog's urine that is the most significant factor affecting the grass. The body excretes nitrogen as a waste product in the form of urea, which is broken down into ammonia by bacteria in the soil. At high concentrations, ammonia is toxic to plants. It burns grass the same way that excessive nitrogen-based fertilizer does. Have you ever noticed how well grass grows around a urine-scalded spot? This is because the nitrogen from the urine eventually acts as a natural fertilizer, promoting grass growth. If yellow spots are reseeded, they grow well the following season.
If you suddenly see more dead, yellow spots on your lawn, your dog may be suffering from a urinary-tract infection. Dogs with these infections have bacteria in their urine. The bacteria manufacture an enzyme called urease that breaks down urea into ammonia and kills lawn grass more aggressively than the urea in normal urine. The conversion of urea to ammonia makes the dogs urine more alkaline. (Veterinarians measure the urine's pH and use it as a screening rest for infections.)
Urine salinity the salt content-is the third important factor in urine scalding. Concentrated urine has more salt (and more urea) than dilute urine. When the soil is unable to buffer the amount of salt and nitrogen in the urine, the grass dies. But the negative effects of high levels of salinity and nitrogen can be counteracted by diluting the urine with water. Thus, you can save your grass by following your dog around with a hose or a bucket of water and immediately splashing it over the spots where she urinates. But if you have better things to do with your time, you can get the same effect by encouraging your dog to drink more water, making her urine more dilute and less toxic.
One way to increase your dog's water intake is to feed her canned food rather than dry. Canned food is 75 percent water, so your dog will take in a lot more fluid eating canned food compared to dry kibble. Another way to promote water intake is to soak dry food in water before feeding. You can even try dropping the dry food into her water bowl so she'll lap up water as she retrieves pieces of food.
A side benefit of increasing your dog's water intake is that she will also be at a lower risk for urinary-tract infections and bladder stones (see sidebar). She'll produce a large volume of diluted urine that effectively flushes our the bladder regularly. (Your veterinarian can do a simple test to see if the urine is sufficiently dilute.)
Another effective way to combat grass scalding from urine is to build up the soil's natural buffets. This can be done by leaving grass clippings on your lawn or by sprinkling compost, pear moss, or wood ashes on your grass. This builds the soil's ability to withstand a sudden dump of nitrogen. Another option is to forego a grass lawn entirely and landscape with clover instead. Clover lawns aren't subject to urine scalding the way grass is.
The last way to prevent a ruined lawn is simply to train your dog to urinate in an area where scalding marks are of little consequence. That way it won't matter how often she urinates, whether her urine is acidic or alkaline, or whether it is too concentrated.