What Is Herbicide Poisoning in Dogs?

Barri J. Morrison, DVM
By Barri J. Morrison, DVM on Aug. 25, 2023
A dog walks by some plants.

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What Is Herbicide Poisoning in Dogs?

During the spring and summer, when abundant sunshine and warm weather prevail, it’s a great time to enjoy your home garden or venture into the great outdoors. While we love to bring our pets along for these fun outdoor activities, we must ensure their safety by preventing their exposure to anything harmful.

Herbicides are chemicals used to manage unwanted plants and weeds. Most of them have a wide safety margin for dogs and cats, as these products tend to be specific to plants and typically pose no harm to animals. However, there are certain herbicides that can be toxic to dogs.

Typically, herbicide toxicity in dogs arises when a dog has been exposed to large quantities of the herbicide due to improper use or from leaving the containers in places your dog can easily reach. In most cases when a dog has been exposed to toxic amounts of an herbicide, they exhibit gastrointestinal symptoms. However, exposure to larger quantities or small amounts over a longer period (chronic exposure) can lead to severe neurologic and cardiovascular impairment. Because the kidneys and the liver are responsible for detoxifying the body, these organs are often affected by any poisoning in dogs.

Herbicide toxicity can result not only from ingestion but also through direct contact with the chemicals, affecting the eyes, skin, and upper respiratory tract if inhaled. If your dog has come into contact with or ingested an herbicide but isn’t displaying obvious signs, contact the Pet Poison Helpline at (855) 764-7661 to determine the extent of the toxicity with professionals. If your dog is displaying any symptoms, seek medical treatment immediately by taking them directly to the nearest veterinarian or emergency room.

Common Herbicide Products

More than 200 active ingredients are used as herbicides, with varying levels of toxicity to dogs.

  • Inorganic herbicides

    • Borax (Sodium borate)

    • Sodium chlorate

  • Organic herbicides

    • Bipyridyl compounds

      • Paraquat

      • Diquat

    • Glyphosate herbicides

      • Roundup®

      • Rodeo aquatic herbicide

      • Eraser A/P herbicide

    • Chlorophenoxy herbicides

      • Mecoprop (MCPP)

      • 2, 4-D

      • MCPA

    • Benzoic acid herbicides

      • Dicamba

      • Chloramben

    • Pyridine herbicides

      • Dithiopyr

      • Triclopyr

    • Dinitroaniline herbicides

      • Dinoseb

      • Binapacryl

      • DNOC

    • Benzamizole herbicides

      • Isoxaben

Symptoms of Herbicide Poisoning in Dogs

Clinical signs of herbicide poisoning can appear from 30 minutes to 24 hours after exposure and may include:

  • Drooling or excessive drooling

  • Vomiting

  • Anorexia (change in appetite)

  • Diarrhea

  • Lethargy

  • Weakness, inability to stand

  • Abdominal pain

  • Skin irritation

  • Eye irritation

  • Convulsions, twitching, seizures

  • Dilated pupils

  • Excessive water intake/drinking

  • Ulcers in the mouth and the gastrointestinal tract

  • Kidney failure

  • Liver damage

  • Trouble breathing, pulmonary fibrosis

  • Ataxia, resulting in an abnormal gait

  • Elevated or decreased heart rate

  • Collapse

  • Myotonia, where muscles are unable to relax

My Dog Ate Grass Treated with an Herbicide. Now What?

Regardless of the amount of herbicide your dog has ingested or been exposed to, it is always advisable to consult your veterinarian or a toxicologist at the Pet Poison Helpline to determine next steps. If your dog is already showing signs of toxicity or irritation, see an emergency veterinarian as soon as possible.

If you have the bottle or packaging of the herbicide product responsible for your dog’s poisoning, take a photo to show the veterinarian to help with their treatment. It is never recommended that you induce vomiting in your dog at home without the guidance of a veterinarian, as this can lead to more serious consequences, including aspiration pneumonia or severe damage to the lining of the stomach and esophagus.

Treatment of Herbicide Poisoning in Dogs

Herbicide toxicity is treated based on the signs and symptoms your dog is having, which are identified by your veterinarian through a physical examination. In cases where the herbicide has come into contact with the skin, an immediate bath using a mild soap is recommended. For oral exposure, the mouth should be rinsed profusely with tap water. However, caution should be taken when the mouth is flushed to ensure that your dog does not aspirate the water. Contact your veterinarian first to determine how to proceed.

If the eyes are affected, your vet will perform a saline eye flush for 5–10 minutes to lessen potential harm. If your dog has ingested an herbicide within the last few hours (without showing any clinical signs yet), your vet might choose to induce vomiting to expel as much of the poison as possible before it absorbs into the dog’s system. Activated charcoal might be administered to minimize herbicide absorption in your dog’s gastrointestinal tract.

Your veterinarian will also perform blood and urine testing to assess potential organ damage. This will also help guide their treatment plan. Treatment of symptoms your pup is displaying typically entails hospitalization with intravenous (IV) fluids, anti-nausea medications, antibiotics for diarrhea, antacids, and other medications, depending on your dog’s needs. Affected dogs should be monitored for at least 24 hours after their symptoms diminish.

If liver disease or kidney disease is evident, then lifelong management may be necessary for these conditions, which are often a result of severe toxicity or a delay in getting your dog medical attention when they have ingested or been exposed to herbicides. Prolonged exposure to herbicides can also cause liver or kidney disease, with your dog developing toxicity over time.

Keeping Dogs Safe from Herbicide Poisoning

To reduce the risk of herbicide poisoning in your dog, ensure that all weed killer chemicals are stored out of your dog’s reach. When using these herbicides, exercise caution around your dog’s presence to prevent skin and eye exposure, as well as inadvertent licking or drinking of the chemicals.

If possible, households with pets should avoid using chemical herbicides altogether, and instead explore natural alternatives that are less likely to harm your dog. Keep dogs off areas of grass where a weed killer has been applied while the product is still wet. Allowing the product to dry thoroughly reduces the potential toxicity that your dog could encounter.

Herbicide Poisoning in Dogs FAQs

What should you do if your dog has eaten grass with Roundup® sprayed on it?

If your dog has consumed grass treated with Roundup®, contact the Pet Poison Helpline or your veterinarian for advice on the appropriate steps and timing for medical care. If your dog’s behavior has changed or they are displaying symptoms, they should be taken to a veterinary emergency room immediately. 

How long before an herbicide is safe for dogs?

Roundup® is primarily toxic to dogs when the product is still wet on the grass. The best practice is to keep your dogs away from treated grass for at least 24 hours. Still, even after the product has dried, in rare instances toxicity can occur.

Should dogs walk on grass with herbicide?

Ideally, avoid allowing your dog to walk on grass that has been treated with herbicides. If they do come in contact with treated grass, make certain they do not lick or ingest the grass and, upon returning home, clean their paws and legs with soap and water.

Featured Image: iStock.com/demaerre

Barri J. Morrison, DVM


Barri J. Morrison, DVM


Barri Morrison was born and raised and currently resides in Ft. Lauderdale, Florida. She went to University of Florida for her...

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