Lawn burn from dog feces and/or urine can be a frustrating problem for home owners.  Most burn spots can recover with time and regrowth, but can be bad enough to require resodding or reseeding of the lawn.  The problem is common and even though people love their dogs, many people also love a well manicured lawn.  Understanding the interaction between dogs and the lawn can help keep peace in the family.

Causes of lawn burn

The problem with the presence of urine or feces on the lawn is related to the concentration and nitrogen content of these waste products.  Urine removes excess nitrogen from the body.  Nitrogen waste is the result of protein breakdown through normal body processes.  Cats and dogs, being carnivores, have a large protein requirement.  Urine volume and production will vary depending on the pet's size and metabolism.  Urine is a bigger problem for lawns than stool because it is applied in concentration as a "liquid fertilize".  Feces slowly release waste products over time.  Stool can be removed more frequently, thus reducing lawn burn caused  by feces, whereas urine cannot be removed and thus is the bigger contributor to lawn burn.

Who is worse, dogs or cats?

Dogs are a bigger concern to the lawn-concsious pet owner simply because cat urine is produced in smaller amounts and they also usually like to eliminate in dirt rather than grass.  Young dogs, both female and male, frequently squat to urinate.  Leg-lifting in male dogs (neutered or unneutered) is typically learned after one year of age.  Most male dogs lift their leg and will mark different areas.  However, some male dogs will continue to squat to void.  Some female dogs may also mark small areas.  Once a dog starts marking different areas, smaller amounts of urine are deposited, resulting in small-volume nitrogen bursts which is easier on the grass.  However, the bushes or shrubs where the dog marks may die because of the nitrogen in the urine due to repeated marking.  Males and female dogs that squat to void will deposit larger volumes of urine, thus causing urine scald on the lawn.  Be aware, not ALL dogs (male or female) cause urine scald.  It varies between dogs.

Primary concerns to look at

The primary concern in reducing lawn burn is to minimize the amount of urine being added to the lawn during a given time.  Female dogs and male dogs that squat to urinate are the primary culprits of lawn burn.  This results in a large volume of nitrogen being introduced onto the lawn all at once.  The nitrogen overload at the center of where the urine was deposited causes the burn spot, but the outer ring is usually bright green due to less nitrogen being deposited to that area as the urine spreads outward.  This has a fertilizer affect and causes the bright green grass around the center of the burnt patch.  Urine concentration and volume of urine have the most deleterious effects on the lawn.  In studies, the pH of the urine did not have a large effect on causing lawn burn, nor did common additives designed to alter urine pH.

Which grasses are better equipped to show less lawn burn?

In studies, of four grasses tested, Festuca species variant Kentucky (fescue) and Lolium perrene (fine-bladed rye) were the most resistant to urine burn.  Poa pretensis (Kentucky bluegrass) and Cynodon species variant fairway (Bermuda grass) were much more sensitive to urine concentration and severe burns.  Even on the most urine-resistant grass (fescue), urine concentration was a larger problem than urine volume.  Concentrated urine with volumes as little as 1 ounce caused lawn burn, even on fescue grasses.

Avoiding Problem Areas

Unfortunately, no commercial repellents are universally effective in protecting lawns.  Hot and bitter repellents are more likely to have a taste repellent effect than an odor repellent effect.  In fact, some odor repellents may encourage a dog to overmark the area with their urine.  A motion-activated sprinkler system can help keep cats and dogs out of certain areas of the yard.  Fencing off an area of the yard where elimination only can take place may be acceptable to some pet/home owners.  The rest of the yard can be spared while only one area of the yard is "sacrificed" for the greater good of the lawn!  Although it can be time consuming, walking a dog to a nearby park is a simple remedy.  But be a good neighbor and don't let your dog cause lawn burn on your neighbor's front lawn.  Smaller breed dogs have been litter box trained by some owners, thus dispensing away with outdoor elimination entirely.  Puppies, as well as adult dogs, can also be trained to eliminate in only one part of the yard.  Going outdoors with your dog on a leash to the designated area (if it is not fenced off) and rewarding your dog with treats after he/she eliminates in the appropriate area can help train your dog to eliminate in this area only.  Consistency is the most important thing when doing this training exercise.  It may take 2-4 weeks to train/retrain your dog to eliminate in one area only and leave the rest of your yard alone. Many dogs can be trained to do this and thus eliminates the need to fence off a designated area.

Dietary Modification

Many dietary modifications to control nitrogen content in the urine have been tried.  A veterinarian should always be consulted before doing any dietary changes/additions to your pet's food.  Again, studies show that urine pH is not a big factor in causing lawn burn, thus adding acidifiers to your pet's food (such as methioform, vitamin C or cranberry juice), has no benefit and may predispose your pet to developing bladder stones.  Also, alkalinizing agents, such as baking soda, can predispose your pet into developing a different type of bladder stone or infections.  Overall, they are not recommended.

Making your dog's urine more dilute by feeding canned food or adding water to the dry food can help reduce the concentration of the nitrogen in the final urine product.  Salting your dog's food is not recommended as a way to increase water intake.  It can contribute to other problems and thus should be avoided.

Avoiding Damage

Walking your dog will reduce lawn damage (assuming your dog will urinate in the park/open space) and also give you and your dog exercise.  Dumping a bucket of water onto the spot your dog just urinated on can dilute out the nitrogen that has just been deposited.  This requires having a bucket at the ready and racing outside to dump it onto the area immediately after elimination.  Many owners are busy enough without having to do this.  Many areas in the United States are in drought areas and frequent watering cannot be done in order to keep the lawn moist and thus reduce lawn burn.  Areas with drier climates and less humidity will have more lawn burn issues than in areas with humidity and moisture.  Using gypsum or lime on your lawn has been advocated, but it has not been proven and it is unknown how it works even if  it does help.  Lawn burn, when mild, can be self-repaired with time.  Larger areas may need to be resodded.  Installing heartier grasses, (e.g. fescue) in place of Kentucky blue-grass may allow for less lawn burn as well. Seek out your local horticulturist if you are landscaping/relandscaping your yard.  Training your dog to eliminate in one area can also help keep peace within the family.  There is no cure or miracle pill to give your pet to stop lawn burn, but there are ways to help reduce the damage.  Consult your veterinarian for additional suggestions or to come up with a plan to help your dog and your lawn!

*Information for this article was obtained from Dr. Thompson's article ""Dog-On-It"; Lawn Problems Revisited" in the Veterinary Forum magazine, July 2004, pgs. 26-31.