“Dog-On-It’ Lawn Problems Revisited

By Steve Thompson, DVM, DABVP

Dog urine and feces can often be a frustrating problem when considering the issue of lawn care.  Small amount can produce a “green up” or fertilizer effect, whereas larger amounts often result in dead brown patches or lawn burn, which are frequently surrounded by a green outside ring.  While most burn spots can recover the time and regrowth, they can be sufficiently severe to require reseeding or sodding.  For homeowners who are also dog lovers, this can present a difficult challenge, especially when one family member prefers the dog and another prefers a well-manicured lawn.  An understanding to the interaction between dogs and he lawn can keep the yard at peace, not in pieces.

Understanding the Causes

The Bigger Problem: Urine or Feces?

            The fundamental problem with the presence of urine or feces on the lawn is related to the concentration and nitrogen content of these waste products.  As a waste product in animals, urine 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 cat and dogs, has a substantial protein requirement, and urine volume and production vary according to a pet’s size and metabolism.  Urine is a bigger problem for lawns that feces because it is applied in concentration as a liquid fertilizer, whereas feces slowly release the waste products over time.  Because stools are usually solid, owners have the option of frequently removing the waste themselves or hiring a commercial pooper-scooper business.  If feces are removed frequently, there is less time for the nitrogen by-products to dissolve and therefore less damage than can occur from urine.

Considering Human Health Concerns

            Removal of feces also reduces bad odors, fly breeding, and human health concerns related to the transmission for some diseases from dogs to humans, including Salmonella, Campylobacter, roundworms (visceral larval migrans), and hookworms (cutaneous larval migrans ore creeping eruption).  As all veterinarians know, children are primarily at risk because they are likely to wash their hands after playing in areas where dogs may have defecated.  The canine roundworm Toxocara canis is of particular concern because the eggs passed in canine stools are resistant to disinfectants and weather extremes for many years. Although uncommon after being ingested by a child, then worm can migrate through the body and cause problems related to vision, breathing, or neurologic disorders.  This is the primary reason many communities enacted pooper-scooper laws and why canine and feline feces should not become part of composting.

The Worst Culprit: Dogs or Cats?

            Dogs are a greater concern that cats to the lawn-conscious pet owner because of the smaller volume of feline urine and cat’s elimination behaviors.  Cats generally mark bushes ore trees as sent posts or bury their wastes in a garden rather that eliminating on the lawn, as a dog typically prefers.  Young dogs of both sexes frequently squat to urinate.  Leg lifting is often learned by male dogs around 1 year of age – castration or neutering does not seem to affect nature’s timetable for this behavior.  Although most male dogs hike their leg and mark, a few males do continue to squat when urinating, which is more typical of female dogs.  Female dogs may also mark, although less commonly than male dogs.

  Once dogs begin urine marking the often find many sent posts, resulting in numerous, small-volume urination rather that large-volume puddles.  Grass can handles small-volume nitrogen bursts easier that fertilizer overload.  Unfortunately, the young bush, scrub, vine, or tree sprout that becomes a marking post may die because of nitrogen (fertilizer) overload from repeated marking.

Addressing Some Primary Concerns

            When addressing urine damage to lawns, the primary concern is minimizing the amount of urine being added to the lawn during a given time.  Female dogs, being less likely to urine mark and more likely to squat are the primary culprits of lawn damage because they urinate anywhere are usually all at once.  This results in single nitrogen dump confined to a small patch of grass.  The brown spot that results often has a green ring around the outside.  The nitrogen overload at the center causes the burn, bus as the urine is diluted toward the periphery, is has a fertilizer effect.  These characteristic brown spot, green-ring pattern has been called “female dog spot disease” by some horticulturists.  As might be expected, lawns are most susceptible to nitrogen burns when a maximum amount of standard fertilizers are applied to the lawn, especially in homes with a comprehensive lawn care program.  Homeowners making the extra effort to maintain a green lawn may become discouraged by the degree of damage caused by neighbors or their own dog.

            Speculation on the actual cause of lawn burn has resulted in numerous theories on what else in the urine may be contributing to the damage.  A.Wayne Allard, DVM, a Colorado veterinarian, examined numerous variations in dog urine and its effects on several common lawn grasses.  His results supported the fact that urine concentration and volume of urine (nitrogen content) had the most deleterious effects on lawns.  The pH of urine did not have a variable effect, nor did common additives designed to alter urine pH. 

            Of the four grasses tested, Festuca spvar Kentucky (fescue) and Lolim perrene (fine-bladed rye) were the most resistant to urine effects.  In fact, urine routinely produced a fertilizer effect on these grasses at diluted concentrations.  Poa pretensis (Kentucky bluegrass) and Cynodon sp var fairway (Bermuda grass) were very sensitive to urine concentration and severe burns, persisting longer that 30 days after initial exposure to even 4 oz of dilute urine.  Even on the most urine-resistant grass that was tested (fescue), urine concentration was a larger problem than urine volume.  Concentrated urine with volumes of as little as 30cc (1 oz) caused lawn burn, even on fescue grasses.

Avoiding Problem Areas

            Obviously, fences can be used to prevent neighboring dogs from eliminating on the lawn.  Advising dog owners about leash laws, where applicable, can also restrict damage to areas near sidewalks, on trees and lawns, and on median right of ways.

            Unfortunately, no commercial repellants are universally effective in protecting lawns, although a variety of home remedies have been tried.  Hot and bitter products are most likely to have taste or odor-adversive properties to dogs.  Most repellants function better as taste repellants that touch or odor repellants.  Some odor repellants may actually encourage a dog to overmark the strange odor with their urine.  Some of the better commercial repellants, such as Garbage Protectors and Ro-Pel, have these limitations as well.  A motion-activated sprinkle designed to keep cats and rabbits out of gardens may be beneficial, such as the Scarecrow marketed by the Canadian firm ConTech.  In addition, the sprinkler may be advantageous in small yards or along corners of front yards, where damage is most likely to occur.  The presence of numerous squirrels, stray animals, or children in the neighborhood, however, may result in high water bill is they continuously trigger the device.

            Although is can be time consuming, walking the dog in a park or field away from the home is a simple remedy.  The time can also be beneficial because exercise has physical and emotional benefits for both dogs and their owners. Homeowners should therefore be encouraged to choose an appropriate destination rather than create problem lawns for neighbors.

            Another option is to litter box train a dog, as breed size and residential space permit, but a more feasible approach is to train the pet to eliminate in a designated area of the yard.  This area could be landscaped specifically to handle the dog’s urine of feces.  It would need a substrate-like pea gravel or mulch that the dog finds acceptable and may even include a marking post, such as a large boulder, bird bath, lawn ornament, or even faux hydrant.  Collecting the dog’s urine in a cup and using it in this area for several days can provide some odor-attractant value that draws the dog to the area.  Feces can also be collected and transported to the new, designated area.  Consistency is important for at least 2 to 3 weeks to establish a routine, trained behavior.  Several months may be necessary in some cases.

            It is important that the dog not be allowed to eliminate anywhere except the designated place during the training process.  This can be accomplished by taking the dog out on a leash to the designated spot and rewarding it with a food treat when it eliminated in the appropriate area.  It is often easier to train a young puppy that an adult dog to a particular area, but such behavior modification is never impossible in a dog of any age.  Many dog owners also find it helpful to train their dog to obey a verbal elimination command.  A dog can also be trained to eliminate on a verbal signal by simply saying the word immediately before it eliminates and rewarding it with a food treat after it finishes.  Common commands include “potty”, “piddle”, “do your business”, and “hurry up.”  Using a command also makes it quicker to accomplish the task during inclement weather.

Dietary Modification

            Many dietary modifications to control nitrogen content in the urine have been tried for dogs, often-based on home remedies or anecdotal experience.  A veterinarian should always be consulted before an owner makes any dietary modifications, whether they include additions or subtractions from the standard nutrient guidelines. As stated earlier, the pH of urine has little or no effect on urine damage to lawns.

            The addition of acidifying agents, including such nutritional supplements as DL-methionine (methio-form), ascorbic acid (vitamin C), or fruit juices, has no benefit and may predispose a dog to developing an increased incidence of certain bladder stones.  Likewise, alkalinizing agents, including baking soda and potassium citrate (UrocitK), can predispose a dog to other types of bladder stones or infections.   These dietary supplements can be harmful and have limited to no known benefits to the lawn.  Thus, they are not recommended.

            When owners have reported successes, they often can be attributed to increasing the dog’s liquid consumption, which dilutes the urine concentration.  However safer ways to accomplish more dilute urine include feeding canned food, moistening dry food with water before feeding, and adding salt or garlic to the regular food.

            One home remedy, tomato juice, likely has it primary benefit through both increased salt and water intake.  While salt can make a dog drink more and thereby dilute the urine, increasing salt intake can also cause problems in dogs with existing kidney or heart conditions.  With high doses of salt, even healthy dogs can develop hyernatremia.  Therefore, owners should not alter their dog’s diet without consulting with their veterinarian.