Yard chemicals and your dog

Lymphoma: A 2012 study in Environmental Research associated 2,4-D exposure with roughly a 70 percent increased risk of canine malignant lymphoma. An earlier 1991 study put it higher; an industry-linked follow-up disputed it; the 2012 work found the association again.

Bladder cancer: A 2013 study in Science of the Total Environment found exposure to herbicide-treated lawns associated with significantly higher bladder cancer risk in dogs, with Scottish Terriers showing up to seven times the risk. Terriers, Beagles and sheepdogs appear more susceptible.

How long it stays on the grass: A 2014 study found herbicides persisting on lawns for at least 48 hours after application — while many product labels tell you to keep pets off for only a few hours.

The finding that should stop you: A 2013 study detected lawn herbicides in the urine of dogs whose own lawns had NEVER been treated, in roughly half of that group. The chemicals drifted from neighboring properties. You cannot fully control this by changing what you use.

Glyphosate: The WHO's International Agency for Research on Cancer classified glyphosate as probably carcinogenic to humans in 2015. Other agencies disagree, and the science is genuinely contested — we are telling you that rather than picking the version that suits an argument.

Being fair about it: The human epidemiology on 2,4-D is less consistent than the canine work, and reviews have found the results hard to replicate. What is not in dispute is that dogs get a much higher contact dose than people do, from the same lawn.

Weed-and-feed. It spreads a broadleaf herbicide — usually 2,4-D — across the entire lawn, which is the maximum possible exposure area for something that lives on that lawn. Decoupling the jobs is the single biggest improvement most people can make: fertilize the whole lawn if you want, and spot-treat weeds only where they are.

· Spot-treat, never blanket-treat. Most of a lawn does not have weeds in it.
· Treat the label's re-entry time as a minimum rather than a guarantee. Given the 48-hour persistence finding, waiting longer costs you nothing.
· Granular products need watering in AND drying before a dog goes back out. Wet granules stick to paws.
· Rinse paws after walks on other people's treated lawns — the flags are there for a reason and most people ignore them.
· Ask your lawn service what they use, in writing. They are legally required to tell you.
· If a neighbor treats, keep your dog off the shared boundary for a couple of days. Drift is documented.

Organic does not mean safe to a dog, and in one specific way it is worse. Blood meal, bone meal and feather meal are extremely attractive to dogs, who will dig them up and eat them. A large ingestion of bone meal can form a cement-like obstruction; blood meal can cause severe vomiting and pancreatitis, and is iron-rich enough to cause iron toxicity. These are common ingredients in organic fertilizers.

Metaldehyde slug bait: One of the deadliest things in a garden shed. Causes tremors and seizures within an hour or two, and it is often flavored to be attractive. Iron phosphate baits are a far safer alternative.

Rodenticide: Anticoagulants, bromethalin and cholecalciferol all kill dogs, and all are designed to taste good. If you must use it, use tamper-resistant stations and know which active ingredient it is, because the treatment differs completely.

Cocoa mulch: Contains theobromine, the same compound as chocolate, and smells like it. Use pine, cedar or hardwood instead.

Antifreeze: Not a lawn product, but it lives in the same garage and is sweet, lethal, and measured in hours. Clean every spill immediately.

· Corn gluten meal as a pre-emergent — it prevents weed seeds germinating rather than killing existing plants
· Horticultural vinegar and fatty-acid burn-down products — non-selective, so they kill grass too, but low residual risk once dry
· Iron phosphate instead of metaldehyde for slugs
· Hand-pulling and a thicker lawn, which is genuinely the most effective weed control there is
· Overseeding and correct mowing height — a dense lawn crowds weeds out without any chemistry

Pet Poison Helpline (855) 764-7661 or ASPCA Animal Poison Control (888) 426-4435, with the product container in your hand. For metaldehyde, rodenticide or antifreeze, go straight to a vet — these are measured in hours, not days.