By MICHAEL TORTORELLO
Published: August 25, 2010

DID Bertie Wooster mean to harm Barbara Geltosky in September 2008? The evidence against him is damning. For instance, the hole that Bertie, Ms. Geltosky’s 5-year-old Norwegian elkhound, dug in the garden was 12 inches across and 12 inches deep — the perfect size for a human foot.
“It was a hole I didn’t see,” said Ms. Geltosky, 59, a retired art teacher who lives with her husband in Malvern, Pa., some 20 miles west of Philadelphia. “I was getting compost when I went down. I twisted my knee badly enough to have rehab.”

Mr. Wooster, who is unemployed, declined to be interviewed for this article. Bertie — the name the dog answers to at treat time — is black and silver with tuxedo markings on his fur. This double-layered coat, which would make lustrous skiwear for Cruella De Vil, helps to explain his excavation habit.

In the dog days of summer, Ms. Geltosky said: “He likes to lay and be cool. Once it warms up, he’ll dig another one.”

Bertie works fast. A hole takes 10 minutes flat. Often, he’s chasing ground bees. Or he might be following his life’s great passion, vole hunting. “We’ve had to put flagstone right next to our patio,” she said. “My husband’s joke is that someday we’re going to have to pave the whole yard.”

This would be a particular sacrifice for Ms. Geltosky, who is a digger herself, and has ringed her house with perennial beds filled with five-foot-tall Tatarian aster and phlox.

Recently, she has been compelled to plant something with absolutely no ornamental value: a four-foot-high wire fence. “We had it shorter, and that didn’t work,” she said. Bertie “really wanted to be on the other side where all the plants were.”

Bertie is not alone in his appetite for destruction. If gardening is a battle — against drought, bug, weed, blight — the dog is a kind of bumbling fifth column, a saboteur who likes to roll on the grass and have his tummy rubbed.

Ask gardeners to describe their dogs, and you will not often hear the profile of a loyal lieutenant. You will hear instead about uprooted flowers, shrubs and vegetables. And a trail of urine burns — on turf and tree — that would put Sherman’s march to shame. The dog plunders low-hanging fruit and leaves pathogenic poop behind. And then, not infrequently, manages to poison itself by wolfing down something toxic.

Dogs and gardens. Gardens and dogs. For compassionate owners everywhere, the two are great and often incompatible loves — like travel and children, or cliff-diving and single-malt Scotch.

Wild dogs “don’t have that much interaction with plants,” said James Serpell, a professor of animal welfare at the University of Pennsylvania School of Veterinary Medicine. For reasons that are not fully understood, he said, they will occasionally nibble grass, a habit that really ought to cross over as a fad diet on the Web site Goop.

“Dogs look at things in the garden, and they have two questions: can I chew it or can I pee on it?” said Ian Dunbar, an animal behaviorist and veterinarian in Berkeley, Calif. “That really is the depth of their philosophy. And they’re happy with that.”

Linda Kocher, 48, is something less than happy with the damage her two dogs, Carl and Bud, have inflicted on her garden in Olivette, Mo., a suburb of St. Louis. Both dogs came from the Humane Society, and their breeding is indeterminate. Carl seems to be part greyhound, and he’s a bolter.

“Bud is a dachshund-Yorkie mix,” Ms. Kocher said. “We call him a dorkie.”

It is Bud that has taken up the steady task of murdering the boxwoods. Ms. Kocher planted a few of the evergreen shrubs last year, with the notion that their foliage would brighten the yard in winter.

Yet, under a steady stream of Bud’s attention (to use a polite term), the leaves have browned and wilted.

“They’re doing what dogs like to do,” Ms. Kocher said. “You can’t get angry with them. You just have to kind of work around them.”

The nitrogen in dog urine would seem to be a helpful fertilizer. In fact, the concentration of ammonium is often toxic to plants. “If you get one of these trees that every dog has to pee on, they can actually burn the bark,” said Nina Bassuk, program leader of the Urban Horticulture Institute at Cornell University.

Exactly how many dogs does it take to kill a tree? “That’s something that hasn’t been studied,” Dr. Bassuk said. “And I’m not going to do it.”

WHEN Anne Heller moved to a house in Santa Barbara, Calif., three years ago, she discovered a small orchard in the yard. The rolling landscape around her family’s 1926 Spanish colonial was home to 12 avocado trees, 3 orange trees, a persimmon, a loquat, a plum, a peach and an apricot.
Her favorite tree might be a “yellow lime” that throws off fruit like beads at a Mardi Gras parade. “I call it the Giving Tree,” said Ms. Heller, 52, who uses the harvest for margaritas.

Unbeknown to Ms. Heller, her 12-year-old chocolate Lab, Moose, had his own favorite tree. One clue was the large, stony pits that started turning up in the dog’s feces. Another clue: he could be found standing upright, on his hind legs, plucking fruit off the lower branches.

Moose was addicted to loquats, a small, super-sweet Chinese import that is a distant cousin to an apple.

Ms. Heller indulges this bit of thievery, as Moose is nearly deaf these days. Or pretending to be nearly deaf. “I guess I’m a pushover,” she said. “I was stricter with my children.”

Given the size of her property — almost three acres — Ms. Heller is often less than dutiful about picking up dog poop. Moose generally wanders to the corner of a distant field. But Pebbles, Ms. Heller’s adopted Australian shepherd, “likes to poop right in the garden,” she said. “In my mind, it’s just fertilizer.”

Fertilizer that might contain the Toxocara canis parasite, according to Sharon Patton, a veterinary parasitologist and a professor at the University of Tennessee College of Veterinary Medicine. (“Worms, bugs, blood and guts are my specialty,” Dr. Patton said.) Toxocara nematodes, or roundworms, live in the intestines of dogs, particularly puppies. And the eggs pass via dog feces.

These eggs can remain in the soil for years. Or, occasionally, the eggs hatch into larvae inside a human host who has mistakenly ingested them, say, from the strawberry patch.

Toxocara larvae are restless houseguests. They like to migrate into human tissue, where they can cause aches and fevers. Another holiday destination: the retina.

“In people, we refer to it as ocular larval migrans,” Dr. Patton said. In rare cases, it can lead to blindness.

Last fall, Pebbles came down with giardiasis, a disease caused by giardia, a one-celled parasite that infects the gastrointestinal tract. Ms. Heller suspects her dog picked it up by drinking from a stream during one of their long walks through the Santa Ynez Mountains, north of town.

Then, in January, Ms. Heller herself contracted the disease, which is marked by nausea, fatigue and digestive grief. “It took a month to kind of feel better,” she said.

The kinds of giardia that infect dogs are often different from the ones that plague humans, Dr. Patton said. “But occasionally we do think there is some crossover,” she said.

For the record, Dr. Patton does not recommend leaving dog feces anywhere in the garden.

OSCAR WILD is a good boy. He does his business where he’s told: the side yard of an old stone carriage house in Ridgefield, Conn., by the border of Westchester County. In the daytime, he likes to lounge outside on the thick-cushioned patio chairs. At night, he sleeps in the bed of Julie Cencebaugh, a 44-year-old painter, who once owned a gallery in Chelsea.

By breeding, the dog is a 4-year-old Brussels griffon. By temperament, “Oscar is part chicken,” Ms. Cencebaugh said.

Oscar keeps close track of developments in Ms. Cencebaugh’s garden. The plantings are formal and English close to the house. Native varieties spill out toward a 350-acre state park that borders the two-and-a-half-acre property.

“You can’t slip a new plant in without him realizing,” Ms. Cencebaugh said. “He’ll sniff the flowers, but he doesn’t do any damage.”

Oscar’s restraint is a boon not just to Ms. Cencebaugh’s garden, but also to his own well-being. The ASPCA maintains an alphabetical compendium of 393 plants that can be harmful when ingested by dogs. It includes apples (the seeds and leaves contain cyanide), baby’s breath (gyposinen), chamomile (bisabolol, chamazulene, anthemic acid, tannic acid) and deadly nightshade (which shouldn’t be a surprise). If something green is growing in the yard, it’s probably on the list.

Given all these ready hazards, it seems flukish that Oscar got into trouble by eating cocoa mulch. With company coming, Ms. Cencebaugh had spread four bags of the fragrant shells on her garden paths.

The smell appealed to Oscar. What did not agree were the stimulants — caffeine and theobromine — that he consumed with the mulch.

“He was like Ricochet Rabbit,” Ms. Cencebaugh said, “bouncing off the wall.” First, she called poison control. Then she shut him in the bathroom for his own protection. “The next day he was fine,” Ms. Cencebaugh said.

Outside, the mulch disappeared for good. But Oscar Wild never knew it was gone. Oscar was back inside, on the softest part of the bed, where a dog naturally belongs.

(Source: A version of this article appeared in print on August 26, 2010, on page D1 of the New York edition.)