Pets and Pesticides

Many people are changing their garden practices when they learn that some pesticides can be very harmful to their pets who spend so much time playing in their landscape.

Pesticides can run off into streams, evaporate or drift into the air, and drain into our groundwater where they can cause harm to us and wildlife. The direct risk to our health from our use of pesticides in our landscape may sometimes be minimized by proper use, and if we do not spend a lot of time in our landscape.

But many people have pets who do spend a lot of time in their landscape. This increases the chances that the pets can be exposed multiple times to pesticides, with the risk of harm often increasing with greater exposure.  

A Tufts University study found that dogs exposed to lawn pesticides were at greater risk of canine malignant lymphoma.
Pets can be more at risk from pesticide poisoning because:

•their smaller size often makes them more susceptible
•they can wander far and be exposed to many pesticides
•they use their noses to explore and noses are an easy place for pesticides to enter their bodies
•dogs sometimes absorb pesticides by chewing and eating treated plant material
•cats can absorb pesticides through their grooming habits
•cats are very sensitive to organophosphates and permethrin pesticides
•cats lack some enzymes that could help their liver decontaminate chemicals

One of the challenges is that it can be hard to diagnose pesticide poisoning in pets and it can take a while for symptoms to show up.

Pesticides of concern
Organophosphates - Malathion, chlorpyrifos, and diazinon are common organophosphates that are the active ingredients in pesticides sold for use by homeowners.  Pets poisoned by these pesticides can be hard to diagnose.  These active ingredients can cause vomiting, diarrhea, seizures, coma, and death.  

Carbamates - Carbaryl is a common carbamate active ingredient.  Cats are especially susceptible to carbamate.  
2,4-D - A Purdue University study linked use of products containing 2,4-D  to increased risk of bladder cancer in dogs.   A Colorado State University study found an increase in the risk of malignant lymphoma for dogs exposed to 2,4-D.  2,4-D is found in Weed and Feed products, which is one of many reasons to avoid use of Weed and Feed products.
Metaldehyde - Used in some slug and snail baits.  It is highly toxic to pets.

Pyrethrins - Less harmful than organophosphates and carbamates because they are broken down quickly when ingested but can cause problems if absorbed through the skin.  Pyrethrins can cause allergic reactions and neurological problems.

Pyrethroids - These are synthetic pyrethrins.  They are a little less toxic than pyrethrins.   Excessive exposure can cause muscle tremors and seizures.  And they are highly toxic to birds and fish as well as mammals.

Piperonyl butoxide - This chemical is a synergist.  When piperonyl butoxide is in a product that also contains other pyrethrins and pyrethroids it makes them more toxic to insects – and also more toxic to your pets and you.  Piperonyl butoxide keeps the liver from detoxifying these products and any other poison you or your pet may encounter.  

d-Limonene - This is made from citrus.  It can be very toxic to cats and you should not use products that contain this if you have cats.  

Garlic Oils -  Pets are very sensitive to the toxic properties of garlic and onions. Short term eating can cause gastrointestinal problems for pets. Long term exposure can create permanent liver and gastrointestinal damage to dogs and cats.
 
Safer Pesticides
Neem Oil - Relatively safe.  Toxic only in very large doses.  

Other oils - Oils from herbs, Cinnamon, Jojoba, Soybean, Sesame, Cottonseed, Castor, Cedarwood, and Citronella appear to be safe.  I have not found evidence of harm to pets.

Bacillus thuringiensis (BT) -  Very safe but has some ability to kill fish.     
Spinosad - Appears to be very safe for pets.

For the safety of your pets and your own health please choose garden products with safe active ingredients.  Beyond the information presented here, if you are unsure about the safety of the active ingredients in a product, please consult our purchasing guides that are available in Country Store, Ace, Island Lumber, and Kathy’s Corner.  Or consult our Garden Green Facebook page which has these purchasing guides along with other information on which products are safe and which have been shown to be harmful.

Michael Laurie is a Sustainability consultant with over 30 years experience.
He and his wife Diane Emerson are working on pesticide and green gardening education on Vashon.