Are Water Plants Toxic to Cats and Dogs?


Last week my friend told me he was planning to create a little garden with a few water plants. However, he was unsure of how his pets- two cats and a golden retriever- would behave with such a garden. Would they drink from the water? Would that be toxic for them? So I proceeded to do some research on the same.

Are water plants toxic to cats and dogs? Some water plants such as hyacinth, lilies and the water surrounding them (for cats), flag iris (for dogs) and some types of algae are toxic to dogs and cats. Water plants toxic to dogs are not necessarily toxic to cats, and vice versa.

Pets can be curious by nature, which leads to much amusement for the owner, but along with that, there is a cause for worry as well as to what the pet cat or dog may lick, touch or ingest that can be harmful to its health. Just like baby-proofing in case an infant is in the house, pet-proofing is also important. This is essential for the outdoors as well, particularly plants kept by you. Potted plants such as tulip and aloe are already known to be harmful to pet cats and dogs, but it is now necessary to discuss which water plants can be toxic to such pets, and which ones are safe. The risk of cats and dogs ingesting these toxic plants becomes higher with water plants as along with the leaves, the animal may decide to drink the water around the plant too.

To begin with, it is important to understand that while several plants may not be toxic to cats and dogs, it does not mean you as a pet owner should encourage the pet to ingest these plants or drink their water. Cats and dogs are naturally curious and mobile animals, which like to explore new things. Sometimes plants and surrounding vegetation catches their fancy and they take bites or drink the water near those plants. While plants that are not toxic to cats and dogs will not be fatal, they may cause indigestion and temporary malaise in the animal, and continuous ingestion in uncontrolled quantities can lead to health complications later in the long run.

Water plants that are toxic to dogs

  • The water hyacinth is a beautiful water plant with large lilac or purple flowers that takes a floating form and grows rather quickly. Many water garden owners don’t mind this plant because of its beauty, but this plant can be highly toxic to dogs, not to mention that it spreads quickly and can become a pest. If the pet dog consumes part of this plant, it can cause sickness in the form of vomiting, diarrhea, lethargy, and possible anorexia.
  • The aquatic iris can be poisonous to dogs, and the extent of sickness depends largely on which part of the plant the dog ingests. In the iris, the bulb, leaves, and root are the main poisonous parts, and in case your dog ingests any of these parts, it is likely to be affected by symptoms such as pain in the abdomen, vomiting, lethargy, depression, irritation in eyes and skin, and if not treated on time, death.
  • Certain varieties of cardinals are popular water plants, but these plants are highly toxic for dogs. Ingesting cardinals, or for that matter, even the smallest parts of the plant, be it a petal or a leaf, can be very harmful to dogs. Common symptoms of cardinal poisoning in dogs include coughing, fatigue, vomiting, muscle pain, and increased heart rate.

Water plants that are safe for dogs

  • Water lettuce is one aquatic plant that is largely safe for dogs. When ingested in small quantities, the plant is absolutely harmless to your dog’s health. Only when taken by the dog in very large quantities- which is unlikely in the first place- it can cause mild stomach pain and indigestion. Feel free to grow water lettuce in your aquatic garden; it is safe for your dog.
  • Duckweed is another water plant that is perfectly safe for dogs as it does not contain toxins that could be harmful to canine systems. On the contrary, duckweed can also form a part of the dog’s vegetarian diet portion if tended to properly and grown appropriately. Thus, duckweed is not at all dangerous for either cats or dogs and the animals can chew on it without fear.
  • Colocasia and water lilies are also safe for dogs. These plants contain calcium oxalates that are insoluble in water and hence none of the substances within the plants can be released in the water surrounding them. Thus, dogs can easily drink the water and not be harmed. However, if ingested, these plants may cause slight indigestion, but are not a cause for concern.    

Water plants that are toxic to cats

  • Lilies, in general, are very dangerous for cats if ingested by them. Water lilies are very popular water plant options for small homegrown ponds, and cats are known to like playing with them and sometimes biting into them. Some varieties of water lily have also harmed cats by causing sickness in the form of vomiting, breathing difficulty, an uneven heart rate that is either too slow or fast, as well as lethargy, and if untreated on time, kidney failure.
  • Taro pond plant is a water plant variety that looks stunning due to its height, but it has been marked at a high level of toxicity for cats. The plant contains toxins that can damage the tissues in the cat’s mouth, throat, and stomach. Symptoms of taro poisoning in cats include vomiting, drooling and consistent pawing at the mouth by the cat due to the burning sensation it must be feeling.
  • Water flag and some varieties of the sweet flag are known to be harmful to cats. Ingestion of this plant by cats can cause irritation in skin, vomiting, diarrhea and burning in the mouth.

Water plants that are safe for cats

  • The mosaic plant is a floating plant that blooms bright yellow flowers in the summer and has red and green leaves. This plant is absolutely safe for cats and will not hurt them if nibbled at.
  • Horsetail is another popular water plant which looks lovely in water gardens because of its reed-like structure and height. This plant is safe for cats, and the horsetail herb is in fact administered in small quantities to animals like cats and dogs to treat urinary tract infections, eczema, and damaged ligaments.

Treatment for cats and dogs that may have ingested toxic plants

It may not always be possible to tell off-hand which plant part your pet dog or cat has ingested, or if the animal’s unease and sickness are being caused by ingestion of plant or plant water. However, recurring vomiting and/or diarrhea are definite indicators of such poisoning. Experts recommend that if the dog or cat keeps vomiting or experiencing stomach upset for more than two days, with no other symptoms, you can take them to the vet for treatment. However, if more serious symptoms are exhibited by the pet, such as continuous lethargy, lack of appetite, perceived depression, visible swelling of face/limbs, difficulty breathing, highly accelerated heart rate or very slow heart rate, you need to take them to the vet immediately.

If the nature of the illness caused by the plant ingested (for example, iris) is gastrointestinal, the vet will likely attempt to induce vomiting in the pet so that the offending substance is expelled naturally- if the pet hasn’t done that by itself already. Activated charcoal may also be used in case a lot of time has passed since ingestion and vomiting may no longer help. In extreme cases, surgery will be done to save the gastrointestinal tract of the pet.

In case the pet is taken to the vet devoid of energy, and lethargic, it will be diagnosed as dehydrated first, and then electrolytes will be administered. At home, if you feel that your pet is dehydrated, you can also administer fluids to it to hydrate. A vet may provide an appetite stimulant to a pet that has a loss in appetite due to plant ingestion, but if you want to do that at home, you can try offering it some tasty treat it enjoys- such as tuna water for cats.

Related Questions

What are some plants or flower varieties pets would benefit from in the garden?

Dogs, in particular, would enjoy the benefits of a garden growing chamomile, lavender, and rosemary, for their soothing and energizing purposes respectively. For cats, parsley, dill, coriander, and basil are great garden varieties and can be ingested safely as well.

What are some terrestrial plants that are unsafe for cats and dogs?

For cats, some plants that are not fatal but are harmful, include kalanchoe, daffodils, all kinds of lilies, tulips, sago palm, autumn crocus, and azaleas. These may cause seizures, oral pain, and swelling. Oleander, black walnut, peonies, and foxglove are toxic to dogs as they cause stomach upset, vomiting and fatigue.

What is Blue-Green Algae? How does it affect people, pets, and livestock?

Blue-Green Algae is not a plant, but bacteria called Cyanobacteria.  Cyanophyta are phylum of bacteria that get their energy from sunlight.  This bacteria can be deadly to your cats and dogs, and very harmful to people and livestock.

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