Veterinary Forum
July 2004
"Dog-On-It"
Lawn Problems Revisited
By Steve Thompson, DVM, DABVP
Originally released in 1998 by the Turfgrass Resource Center, a trade association-funded
information source, this article has been updated for publication in Veterinary
Forum. Given the attention that many clients devote to their lawns, the article
offers some helpful seasonal advice practitioners can share.
Dog urine and fcces can often be a frustrating problem when
considering the issue of lawn care. Small amounts 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 with 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 of the interaction
between dogs and the 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 cats and dogs,
have 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
than 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 of some diseases from dogs to humans, including
Salmonella, Campylobacter, roundworms (visceral larval migrans), and hookworms
(cutaneous larval migrans or creeping eruption). As all veterinarians know,
children are primarily at risk because they are less 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, the 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 a part of composting.
The Worse Culprit: Dogs or Cats?
Dogs are a greater concern than cats to the lawn-conscious pet owner because
of the smaller volume of feline urine and a cat's elimination behaviors. Cats
generally mark bushes or trees as scent posts or bury their wastes in a garden
rather than 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, they often find many scent posts, resulting in
numerous, small-volume urinations rather than large-volume puddles. Grass can
handle small-volume nitrogen bursts eas-
ier than fertilizer overload. Unfortunately, the young bush, shrub, 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 and usually all
at once. This results in a 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, but as the urine is diluted
toward the periphery, it has a fertilizer effect. This 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 a neighbor's 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.1 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 sp var Kentucky (fescue) and Lolium 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 than
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 30 cc (1 oz) caused
lawn burn, even on fescue grasses.1
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 than touch or odor repellants. Some odor
repellants may actually encourage a dog to overmark the strange odor with their
urine. Some of the hetter commercial repellants, such as Garbage Protector and
Ro-Pel, have these limitations as well. A motion-activated sprinkler 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 bills if they continuously
trigger the device.
Although it can be time consuming, walking a 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 or 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 eliminates in the appropriate area. It is often easier to train a young
puppy than an adult dog to a particular area, but such behavior modification
is never impossible in a dog ot 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 standard nutrient guidelines.
As stated earlier, the pH ot 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),1 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 salt to the regular food.
One home remedy, tomato juice, likely has its primary benefit through both increased
salt and water intake. While salt can make a dog drink more and thereby dilute
the urine, increased salt intake can also cause problems in dogs with existing
kidney or heart conditions. With high doses of salt, even healthy dogs can develop
hypernatremia.2 Therefore, owners should not alter their dog's diet without
consulting with their veterinarian.
Dogs with more dilute urine may have to urinate more frequently and therefore
may
need more frequent elimination opportunities. Although specific breed differences
have not been noted, smaller dogs do produce less urine than larger dogs, so
they are dumping less nitrogen waste. Dogs with bladder infections often demonstrate
an urgency to urinate and typically squat several times, leaving small drops
each time. However, affected dogs may actually be less of a problem for lawns
than healthy dogs that empty their bladder during one sitting. Dog owners who
actually note that their dog's urine is no longer causing lawn burn, without
having made any dietary changes, should have their dog examined by a veterinarian
and a urinalysis conducted to make sure no medical conditions are causing the
change.
Another option to consider is reducing the amount of nitrogen waste being dumped
in the urine. The average family dog does not have high-activity dietary needs,
including the high-protein level provided in most commercial maintenance dog
foods. Although dog food purchasing often reflects consumer perception that
high protein equals better-quality food, in fact, moderate- to low-protein foods
are often adequate for all dogs except highly energetic, working, or hunting
dogs. When examining a food label, protein content should be compared on a dry-matter
basis and, unfortunately, it is not like comparing apples with apples. Dry foods
vary in how much moisture they have, so the protein percentage listed cannot
be immediately compared with all other foods. Canned foods have a much lower
protein percentage than dry foods but also have much higher water content.
The quality of the protein also has an impact: Less protein by-product is eliminated
in the feces and urine from highly digestible protein. In general, the premium
and super-premium pet foods available from pet stores and veterinarians have
higher-quality and more digestible protein contents than standard grocery store
brands. Higher digestibility translates into smaller fecal size. It is probably
best to discuss individual pet needs with a veterinarian or veterinary nutritional
consultant to determine what is best for individual dogs based on feasibility,
palatability, and economics. For example, moderate- to high-protein diets are
necessary in older dogs to preserve kidney function, so dietary changes in mature
and geriatric pets should always be made after a veterinarian has been consulted.
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
initial solution.
Avoiding Damage
Taking dogs for a walk not only avoids lawn damage but can function as a bond
between owners and their dog, increasing the time the pet spends interacting
with its owners. A leash can also serve as a great training aid and is one of
the best ways owners can intervene when their pet urinates.
In addition, watering after urination can dilute the area with no ill effects
on the dog. Dr. Allard's study1 looked at watering fescue at different intervals
following urination. Water volumes three times that of the concentrated urine
were used to assess their dilution effects. A fertilizer effect, rather than
burn, was noted when the site was watered up to 8 hours after urination. When
watering was delayed to 12 or more hours, progressively worse burns were noted.
Apparently, routinely watering grass early in the morning does not sufficiently
prevent urine burn.
The use of gypsum or lime has been advocated, but it is uncertain exactly what
mechanism this has in helping to prevent urine damage. Improved soil quality
over time may result in better drainage and less urine concentration at the
grass and root level, but it seems unlikely that drainage can be improved by
applying either additive. As indicated before, altering pH does not affect the
damage that urine can cause.
Lawn burn, when mild, can often self-repair with time, especially in the case
of warm-season turf grasses that spread by stolons and rhizomes. Dark green
spots and taller grasses may remain for several weeks. Installing turf grass
sod can be a quick way to patch severely damaged areas that would otherwise
be invaded by weeds.
Finally, owners can coordinate a comprehensive program with county or state
extension horticulturists, a lawn care resource, and the primary veterinarian.
Doing so can keep four-legged friends on good terms and out of the doghouse.
Key Resource
The Turfgrass Resource Center is funded by Turfgrass Producers International
(TPI), a 37-year-old, independent, not-for-profit association. For additional
information, visit www.TurfGrassSod.org.
Reviewer #1 Comment
To my knowledge, not much has been written on the subject of urination except
by behaviorists whose concerns are an animal's abnormal habits and not the quality
of the owner's lawn. This is a well-written presentation that will catch the
attention of Forum readers.
Reviewer #2 Comment
Veterinarians need to educate owners about the use of home remedies, such as
supplementing a pet's diet with high-salt or methionine-containing products.
It is important that owners understand the potential risks associated with overdosing
these supplements. Thus, all supplements must be treated as medications, and
not treats.
References
1. Allan! AW: Lawn hum and dog urine. Canine Pract 8(2):26-52, 1981.
2. Villar D: Overingestion of methionine tablets by a dog. Vet Human Toxicol
45(6):311-3n, 2001
Dr. Thompson is director of the Pet Wellness Clinic/Community Practice, Companion Animal Medicine and Behavior, Purdue University Veterinary Teaching Hospital, West Lafayette, Indiana.