Is Lawn Fertilizer With Weed Control Poisonous to Dogs?

Careful planning on lawn-care day will help keep the vet away.
i dog image by Ergün Özsoy from

Is the grass greener on the other side of the fence? If you are "green" with envy and your lawn is starting to look like a jungle, you may wish to use a lawn fertilizer with weed control. To help keep Rover safe, however, make sure you read those labels carefully.

Product Function

If your grass is craving some food, a good fertilizer may help quench those hunger pangs. Fertilizers are organic or inorganic products meant to supply your lawn with nutrients. If you also have a problem with weeds in your yard, you may be happy to learn that there are actually lawn fertilizers that feed your lawn while providing effective weed control at the same time. These products are often known as "weed and feed" products. While this sounds like a win- win solution, you have your good reasons to be concerned about the safety of your pooch.

Product Components

Most fertilizers contain three main micro-nutrients: nitrogen, phosphorus and potassium. Some may also contain copper, zinc, iron, cobalt, boron, manganese and molybdenum. Meal-based fertilizers will typically contain blood meal, bone meal, feather meal and iron. An "all in one formula" will also contain some weed-control ingredients, such as the herbicides 2,4-D, dicamba and mecoprop.

Product Toxicity

Fertilizers containing blood meal, bone meal or feather meal may appear particularly appealing to dogs. The ingestion of large quantities of meal-based products may lead to a blockage of the gastrointestinal tract and may also cause severe pancreatitis, according to the Pet Poison Helpline. Products containing heavy metals may pose a hazard when ingested in large amounts and products containing iron may lead to iron poisoning instead. The presence of herbicides will further cause a cascade effect, significantly increasing the risk for poisoning.

Product Effects

How your dog may react to the product will depend on several factors such as the size of your dog, the toxic amount ingested and the concentration of the product. While small quantities of fertilizer may cause minor gastrointestinal upset generally lasting for up to 24 hours, larger quantities may result in severe toxic effects. Expect to see drooling, nausea, vomiting and diarrhea, abdominal pain, trouble breathing and brown-colored gums. With the presence of herbicides, expect in such cases neurological problems weakness, tremors and seizures, veterinarian Nick Tomoro explains. If you suspect your "Hoover dog" has ingested a chemical lawn product, see your vet immediately and don't forget to take along the lawn-care product so your vet can find the EPA number and product registration number.

Product Long-Term Effects

Repeated exposure to weed and feed products may not always have immediate effects. A study conducted by Purdue University showed that exposure to the herbicide 2,4-D dramatically increased the risk of bladder cancer in Scottish terriers. Don't own a Scottie? Then consider the fact that another study has shown that canines in general were two times more likely to develop lymphoma when exposed to 2,4-D herbicide spread on their lawn four or more times a year. Not to mention the fact that people owning dogs are also more likely to have higher 2,4-D levels inside their homes because dogs carry residual traces of herbicide on their paws.

Product Directions

Most products labeled "safe" for animals have specific guidelines to follow to ensure the safety of pets. Allowing the treated area to dry thoroughly before allowing your dog access to it is important to prevent minor skin or stomach irritation, explains the poison control expert of the American Society for the Prevention of Cruelty to Animals Poison Control. Better off, keep your dog off the area for several days after application, since weed killer to be effective has to stick to the leaves and should not be rinsed off for at least 48 hours, Tomoro further explains.

Product Safety

While weed-feed products appear to be less harmful once dried, it certainly doesn't hurt to err on the side of caution. Avoid over-applying the product and follow the instructions carefully. Watering the treated lawn and preventing Rover from walking on it until it dries helps prevent residue from being transported to the home. Better off, if you are not comfortable using chemicals in your yard, use organic products containing non-toxic materials. Your dog and your lawn will thank you.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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