Beautiful Lawns and Pets — Not Exactly a Match Made in Heaven

Published: June 1, 2010

Pet urine can often be a frustrating problem related to lawn care. Small amounts may produce a green spot while larger amounts often result in dead brown patches, usually surrounded by a green outer ring of tall grass. While most burn spots will recover with time and regrowth, burns can be severe enough in some cases to require some sort of lawn maintenance. This can be a difficult challenge for homeowners who are pet lovers. Understanding what’s happening may help pet lovers keep their yards in better shape.

Fundamental problems with the presence of urine or feces on the lawn is related to the concentration of ammonia (nitrogen) content in these waste products. Urine, when produced as a waste product in animals, primarily removes excess nitrogen from the body via the kidneys. Nitrogen waste products are the result of protein breakdown through normal bodily processes. Carnivores, including cats and dogs, have a significant protein requirement, and urine volume/production varies due to a pet’s size, metabolism, and specie. Urine is a bigger problem for lawns because it is applied all at once in a concentrated stream, whereas feces will slowly release the waste products over time.

Dogs are a greater concern than cats for the lawn conscious pet owner, due to smaller cat urine volume and typical cat elimination behaviors. Cats generally mark bushes or trees as scent posts or bury their wastes in a garden, rather than squatting in the middle of the lawn as a dog may prefer.

While most male dogs (over a year of age) will hike their leg and mark post, a few will continue to squat when urinating, which is typical for female dogs. Female dogs may also mark although less commonly than male dogs. Once male dogs begin urine marking, they often utilize many scent posts resulting in numerous, small volume urinations rather than a large volume puddle. Grass can handle smaller volumes of urine bursts easier than large volumes. Unfortunately, a small bush, shrub, vine or tree sapling that becomes a marking post may often die.

Female dogs, being less likely to urine mark objects and more likely squat, are the primary culprits of lawn damage since they will urinate anywhere on a lawn and usually all at once. This results into a large volume of urine confined to a small patch of grass. Ammonia overload at the center of the patch causes grass burn. This characteristic brown spot has been called “female dog spot disease” by many horticulturists.

Research has shown that urine concentration (ammonia content) and volume of urine had the most deleterious effects on lawns. Of the four grasses tested, tall fescue (Festuca spp.) and perennial ryegrass (Lolium perrene) were the most resistant to urine effects. In fact, the urine routinely produced a fertilizer effect on these grasses at diluted concentrations. Kentucky bluegrass (Poa pratensis) and bermudagrass (Cynodon spp.) were very sensitive to any urine concentration and severe burns resulted, persisting greater than 30 days after initial exposure to even four fluid ounces of dilute urine. Even on the most urine resistant grass tested (tall fescue), urine concentration was a bigger problem than urine volume. Concentrated urine with volumes as little as one fluid ounce caused lawn burn even on tall fescue.

Dietary Modifications

Many dietary modifications for dogs have been tried, often based on home remedies or anecdotal experience. Veterinarians should always be consulted prior to making any dietary modifications, whether they include additions or subtractions from standard nutrient guidelines.

When dog owners reported successes on internet forums, liquids (water) improved the problem since the urine concentration after treatment was diluted. Safer ways to accomplish more dilute urine include feeding canned food, moistening dry food with water prior to feeding and making sure your pet has sufficient water intake in its diet. Dogs with more dilute urine may have to urinate more frequently and need more frequent elimination opportunities. While specific breed differences haven’t been noted, smaller dogs produce less urine than larger dogs. Dog owners, who actually notice their dog’s urine is no longer causing lawn burn, without making any changes, should have their dog examined by their veterinarian with urinalysis performed to make sure there are no medical conditions causing this change.

Another option is to consider the high protein diets many dog are on. Proteins contain nitrogen and the average dog doesn’t have the activity that requires a high protein level that most commercial dog foods provide. Although dog food purchasing often reflects consumer perception that high protein equals better food, when in fact, moderate to low protein foods are often adequate for all but the most energetic, working, and hunting dogs. When examining a food label, protein content must be compared on a dry matter basis and unfortunately, it is not like comparing apples to apples. Dry foods vary moisture content, so the protein percent listed can’t be immediately compared to all other foods. Canned foods will have a much lower protein percent listed than dry foods and have a much higher water content. Moderate to high protein diets are necessary in older dogs to preserve kidney function, so diet changes in mature and geriatric pets should always be in consultation with a veterinarian. If a dog food is currently providing good, overall nutritional support for the pet, diluting the urine by simply adding water to the food, may be the easiest place to start.

A variety of dog biscuits are also available that can reduce urine concentration. However, your local veterinarian should always be consulted for any recommendations to include such a product in your pet’s diet.

Other Options

Fences can be used to keep neighboring dogs from eliminating on your lawn. Advising neighbors of the legality of leash laws, where applicable, can restrict damage to some areas near sidewalks and median right of ways. Unfortunately, no repellants are universally effective although a variety of home remedies have been tried. Most repellants function better as taste repellants than touch or odor repellants. However, some odor repellants may actually encourage a dog to over mark the strange smell with their urine.

In many situations, walking the dog to a park or field away from the house is a simple remedy to this problem. The time can be well spent since exercise has physical and emotional benefits for dogs and their owners. Homeowners are encouraged to choose an appropriate area that does not create problem lawns elsewhere in the neighborhood.

Another option is to litter train a dog, if size and space permit. A more feasible approach is to train the pet to eliminate in a designated area of the yard. This area should be landscaped specifically for the dog. It will need a substrate like pea gravel or mulch that the dog finds acceptable and may even include a marking post like a large boulder or fake hydrant. It is very important the dog not be allowed to eliminate anywhere but the designated place during the training process. This could be accomplished by taking the dog out on a leash to the designated spot and rewarding your pet with a treat when he/she eliminates in the appropriate area. Consistency is important for at least 2-3 weeks to establish this as a routine, trained behavior; several months may be necessary in some cases.

It is often easier to train a young puppy to a particular ground texture than an adult dog, but never impossible in any age dog. Many dog owners will also find it helpful to train their dog to an elimination command during this time. Dogs can be trained to eliminate on a verbal command by simply saying the word immediately before your pet eliminates and rewarding them with a treat after finishing. Common commands might include: Potty, Go, or Hurry Up, etc. and make it faster to accomplish the task when inclement weather is present or time is short.

Repair/Recovery of Urine Spots

Watering the spot after urination will accomplish the dilution with no ill effects on the dog. Water volumes three times that of the concentrated urine can result in a fertilizer effect rather than a burn effect if applied within prior to eight hours of elimination. When dilution exceeds 12 hours, lawn burns develop.

The use of gypsum or lime has been advocated to improve urine effects on lawns. Gypsum may provide improved drainage and less urine concentration at the grass and root level, but has proven to be very temporary. Gypsum does reduce salt levels in the soil by binding with the salts present and making them more soluble. Lime may alter any pH effects, however research has shown pH is not an issue with pet urine.

Lawn burn, when mild, will often self repair itself over time, especially in the case of the warm-season turfgrasses that spread by stolons and rhizomes. Dark green spots and taller grasses may remain for several weeks creating a spotty looking lawn. Installing new sod can be a quick way to patch severely damaged areas that would otherwise be invaded by weeds.

While a high fence and dogless lifestyle can ensure that “female dog spot disease” is not a problem in your yard, homeowners and dog lovers have several practical options available to manage or reduce this problem. Developing an approach to this problem through various resources (county or state extension horticulturist, lawn care provider, and your veterinarian) can keep your four-legged friend on good terms and out of the dog house.

Information for this article were reprinted from ‘DOGON-IT’ LAWN PROBLEMS.

Source: Dr. Steve Thompson, DVM
Director - Wellness Clinic/Community Practice
Companion Animal Medicine & Behavior
Veterinary Teaching Hospital
1249 Lynn Hall
West Lafayette, Indiana 47907-1249
Phone: 765/494-1107 or 765/496-1000
Fax: 765/496-1025
E-Mail: sthompso@vet.purdue.edu