Reality Check: Plants Don't Pose a Big Risk

If ingested, the odds of toxicity are slim, but do use common sense.

It's a widely held belief that many plants pose mortal danger to dogs. A Google search of "toxic plants dogs" results in more than 750,000 pages detailing the poisonous properties of hundreds of species of flower, plant, shrub and tree. While this seems alarming, the reality is that plant-related deaths are uncommon among dogs, and with a little common sense you can keep yours safe.

He'll Chew on Leaves Out of Curiosity But Not Eat Them
Puppies are at the most risk of getting into trouble. "Young dogs are more likely to chew on plants than older dogs because they're more inquisitive," said Scott Shaw, DVM, a specialist in emergency and critical care at the Cummings School of Veteri¬nary Medicine at Tufts University.
If a puppy consumes a large quantity of a toxic plant such as azalea or rhododendron, he may experience gastrointestinal tract upset, vomiting, diarrhea, depression of the central nervous system or even coma or death. "Safe" plants can also pose problems. "Some types of plants can cause mechanical injuries to the tissue of the mouth, and any plant, even if considered nontoxic, can irritate the stomach," said Dana Farbman of the ASPCA's Animal Poison Control Center.

The good news: Puppies usually chew leaves but don't eat them, and if they do, they usually need to swallow major quantities to be affected. For example, while English ivy is considered toxic, one swallowed leaf won't be enough to create toxicity, Dr. Shaw said. Farhman agreed: Most of the exposures we see involve more than just a lick. We're talking about actually consuming plants."

However, a few plants or their seeds are so toxic that even minimal ingestion can cause death. According to the School of Veterinary Medicine at Purdue University, the most dangerous plants for dogs include castor bean (primarily the seeds), jimsonweed, English and Japanese yew, oleander and rosary pea. To help limit the risk to your pup, discourage him from chewing on any kind of plants and remove highly toxic plants from your home or yard. The APCC maintains a list of toxic plants at www.aspca.org/site/DocServer/poisonousplantsdogscats.pdf?doclD=109.

The Most Common Toxic Plant They Ingest: Marijuana
A common misconception IS that adult dogs have an innate warning sense and won't eat a poisonous or bad tasting plant. "If only that were so!" Farbman said. "Dogs have very indiscriminate eating habits and will cat just about anything."
But the odds of your dog being seriously affected by plant toxicity are fairly slim, Dr. Shaw said. "We really don't see a ton of cases like that. We get a lot of calls about poinsettia, but we tell people it's not really that big a deal." The public mistakenly believes this plant is deadly, while ingestion may be only slightly irritating to the gastrointestinal tract.
Perhaps surprisingly, the most common toxic plant that dogs ingest, according to the APCC, is marijuana. Dr. Shaw concurred: "The most com¬mon plant toxicity we see is marijuana ingestion."
Adult dogs may encounter other sorts of plant problems. Dogs who frequently go off-leash in fields or woods can come into contact with plant awns such as foxtails, which can lodge between toes or in soft tissues and create painful abscesses or even migrate into the dog's body, leading to a host of problems. Roaming dogs can also run into brambles, thorns or stinging nettles, Dr. Shaw said.

Limit His Access to Areas Treated With Pesticides
Because the liver and kidney metabolize ingested toxins, geriatric dogs with renal or liver failure may be more affected by ingesting poisonous plants than healthy younger dogs. But even if your dog is more likely to doze on the lawn than gnaw your bushes, lurking fertilizers, herbicides and insecticides might harm him.
"Most of the herbicides and fertilizers available for residential use are fairly benign when used appropriately," Farbman said. Allow treated areas to dry thoroughly before giving your dog access to them. However, if your dog eats large amounts of any of these items, he's at risk for serious gastric upset and possible gastrointestinal obstruction. In addition, some studies have linked a higher incidence of transitional cell carcinoma in dogs to exposure to herbicides, according to the April 15, 2004, issue of JAVMA, the journal of the American Veterinary Medical Association.
Pesticides can pose a bigger threat. The APCC lists the most dangerous pesticides as snail bait (metaldehyde), fly bait (methomyl), systemic insecticides (disyston, disulfaton), mole and gopher bait (zinc phosphide) and most forms of rat poisons.
To minimize risks, follow application instructions to the letter and limit your dog's access to newly treated areas. Also, consider us ing natural alternatives to pesticides, such as sprinkling table salt in the garden instead of snail bait or using vinegar to kill dandelions.

C. C. Holland is a free-lance writer in Oakland, Calif.

FROM: CUMMINGS SCHOOL OF VETERINARY MEDICINE AT TUFTS UNIVERSITY