Is weed killer harmful to cats?
First Published: 24/04/2024
Last Updated: 14/08/2024
While some weed killers (also known as herbicides) are marketed as safe for cats, this depends on the chemicals used, application methods, and whether owners follow safety instructions. Cats can be exposed to weed killers by walking on treated grass, brushing against treated plants, or being hit by spray drift.
Swallowing toxic chemicals can also happen when cats groom themselves after contact, eat recently sprayed grass or plants, or drink contaminated water. They can also ingest the product directly if they come across a spillage, or an unsecured container.
Symptoms of herbicide poisoning in cats
Cats exposed to toxic weed killers may display a range of poisoning symptoms. These largely depend on the chemicals involved, but usually include sickness, lethargy, and respiratory problems. The main signs of herbicide poisoning are:
- Vomiting
- Lethargy
- Reduced appetite
- Breathing problems
- Diarrhoea
- Dilated pupils
- Drooling
- Abdominal discomfort
- Muscle tremors
- Seizures
Read more: Nine plants that are poisonous to cats
Common weed killer chemicals and their risks
| Chemical | Risks |
|---|---|
| Glyphosate | Used for various weeds, mainly as a liquid. Low toxicity but can cause vomiting, diarrhoea, tremors, and severe respiratory and kidney issues when combined with other chemicals. |
| Chlorophenoxy derivatives | Found in lawn products. Symptoms include drooling, vomiting, lethargy, ulcers, bloody stools, and muscle stiffness. |
| Benzoic acid herbicides | Used in crop fields and orchards. May cause skin irritation, stomach upset, muscle stiffness, and coordination issues. |
| Dipyridyl (e.g., paraquat, diquat) | Rapid weed control. Early signs include vomiting and depression, followed by severe respiratory issues and kidney failure. |
When should I see my vet?
If you’re worried your cat has been exposed to toxic chemicals in weed killer, contact your vet immediately, particularly if any poisoning symptoms are evident. Be sure to note the name or ingredients of the product, as this information will help your vet determine the most effective treatment. If possible show your vet the product container, or a photo of it. Quick veterinary care can reduce the severity of symptoms and improve your cat’s chances of recovery.
Diagnosis and treatment for weed killer poisoning
When diagnosing herbicide poisoning, your vet will consider your cat's symptoms and any possible contact with chemicals. They may run some blood tests to check their internal organs. In the treatment room, the vet might start with a decontamination wash to clear the chemicals, give activated charcoal to absorb toxins internally, and provide supportive care like fluids and medication to manage symptoms. They’ll keep a close watch for any complications. In more serious cases, your cat may be hospitalised overnight.
Read more: Is weed killer safe for dogs?
How to prevent weed killer poisoning in cats
To prevent your cat from becoming ill from exposure to weed killers, only use pet-safe herbicides and strictly follow the manufacturer’s instructions. When using products, keep cats away from treated areas until the product has dried, or for as long as the manufacturer advises. Always store gardening chemicals out of your pet's reach, and always clean up any spillages straight away. Consider manual weed removal methods.
Research into weed killer and cats
This scientific study written by vets and titled glyphosate toxicity in animals discussed research on treating cats and dogs who had been poisoned by weed killers containing glyphosate. Although glyphosate was generally considered low in toxicity, it proved to be harmful when combined with other chemicals in gardening products.
Cats poisoned by glyphosate often showed signs like vomiting, lack of appetite, and tiredness, but they were less likely to suffer from diarrhoea than dogs. Cats were especially prone to severe breathing problems when exposed to glyphosate, including cases that led to death. Cats faced a higher risk of dying from glyphosate poisoning, with 22% of cases being fatal compared to 5% in dogs. The findings from this study suggested that while glyphosate might not be very toxic by itself, the additional chemicals mixed with it could lead to serious health issues, particularly in cats.
Another study titled glyphosate-surfactant herbicide poisoning in domestic animals also investigated reports of pet poisonings by glyphosate, collected by the Poison Control Centre of Milan from 2006 to 2012. It found that dogs were poisoned more often than other animals, usually showing stomach upset symptoms like vomiting and diarrhoea. Cats were less frequently poisoned but faced serious issues when affected, with symptoms including vomiting, tremors, and sometimes kidney failure, which could be deadly. Cats had a higher death rate from these poisonings compared to dogs.
Read more: Tips for choosing your cat's boarding place
Common questions on weed killer and cats
Can weed killer kill cats?
As the studies above show, if cats are accidentally exposed to high doses of certain chemicals used in weed killers, either through direct contact or ingestion, it can result in serious health issues, and in extreme cases, death. That's why it's so important to use these products carefully and follow safety instructions.
What should I do if my cat walks on treated grass?
Wash their paws immediately with soap and water and keep an eye out for any toxicity symptoms showing.
Are natural weed killers safer for cats?
Not necessarily, as they may also contain irritants or toxins harmful to cats.
How long after weed killer is it safe for cats?
Although weed killer labels often suggest avoiding treated areas for six to 24 hours, research indicates that chemical residue may linger on surfaces for up to 48 hours after application. Therefore, if you use products like Roundup, it is safest to keep pets off treated grass for at least two days.
Need more info about weed killer and cats?
If you’re worried about weed killer poisoning in your cat or any other aspect of your cat’s welfare, have a chat with your local vet.
Find your nearest vet using our find a vet page, or speak to a vet online using our video vets service.