There are a wide range of plants that are potentially toxic to cats (check out this list for more details!). However, for most plants, poisoning is relatively uncommon because most cats are sensible enough not to try eating them! There are, however, a number that are important, either because cats can be exposed in other ways, or because the plants are so common that poisoning is seen more than very occasionally – and in this blog, we’re going to look at some of the more important plants that are poisonous to cats.
Agapanthus (also known as African Blue Lily).
Although not a true lily (see below!), this plant is also toxic, as when the rhizomes (root bulbs) are damaged they exude a sticky and highly irritant latex-like sap. If licked (for example, if it gets onto the cat’s paw, or if they nibble on the plant from curiosity), symptoms include sudden onset pain, swelling and pain to the gums and mouth, and excess salivation. The tongue and throat then become swollen, and eventually diarrhoea occurs; in very severe cases, the swelling of the throat may make breathing difficult, and this can even be life-threatening.
Agapanthus plants also contain insoluble calcium oxalate crystals, which are found in many other plants (e.g. Anthurium, or Flamingo Lily). These crystals are also highly irritant to the gastrointestinal system, causing drooling, vomiting and diarrhoea, but as they are not adhesive like the Agapanthus sap, the effects tend to be a little less severe, and poisonings are less commonly seen.
As a good cat owner, you probably know not to use dog or rabbit flea products on your cat – because they often contain pyrethrins as their active ingredient, and can cause convulsions, seizures and often death.
Well, pyrethrins come originally from chrysanths, and if eaten, the flowers (as well as other parts of the plant) can have the same lethal effects. Lower doses may also result in vomiting and diarrhoea, followed by incoordination.
A beautiful symbol of spring! However, daffodils – especially the bulbs – contain toxic chemicals called lycorine and alkaloids. If nibbled – and we do occasionally see cats who like to try a taste! – the symptoms are unlikely to be severe, but may include vomiting, salivation and diarrhoea. It is very rare for a cat to ingest enough for more serious symptoms, which can involve heart problems and even tremors or convulsions.
Amaryllis, Hyacinths and Bluebells are quite closely related and contain similar toxins, so again, if your cat has an inordinate interest in them, consider rehoming the plants!
This is the big one – the true lilies, Lilium and Hemerocallis (day-lilies), are lethal to cats. The exact toxin is uncertain at the moment, it is highly destructive to the kidneys. It can be absorbed by nibbling the plant (as little as one nibble of a flower can be fatal), or even grooming after being dusted by pollen from the plant.
The initial effect is called “polyuric kidney injury”, where the cat becomes thirsty and urinates profusely. They become depressed, lose interest in food, may start vomiting, and become progressively dehydrated. Then, unless they have absorbed only a tiny, tiny quantity, they progress to “anuric kidney failure” as the kidneys shut down completely and the cat stops producing urine. This results in collapse, sometimes seizures, and then death.
If treatment can be started before symptoms of kidney failure appear – and certainly before the kidneys completely shut down – the chances are best, but this is a very nasty toxin, and sadly once anuric kidney failure occurs most cats won’t make it even with intensive care.
In general, cats and lilies are a bad mix – and probably should not be living together in the same house!
Lily of the Valley
Convallaria majalis is, again, not a true lily. However, it does contain a wide range of toxic chemicals, including irritant saponins that leach into the water – a major problem can be cats drinking water from vases in which flowers have been put.
The symptoms typically include the usual drooling, abdominal pain, vomiting and diarrhoea; however, the toxins also damage the heart and can lead to rhythm disturbances. In many cases, the onset of symptoms is significantly delayed after ingestion, and poisoning can in many cases be fatal without early treatment.
Lots of people know about poinsettia. This plant oozes a sticky milky sap which is highly irritant to the gums and intestines. This can lead to excessive salivation and vomiting; however, it’s rarely severe, and poisoning isn’t reported to cause fatalities.
While rhododendron poisoning is more commonly seen in sheep and goats, as the pollen is also toxic, toxicity is possible in cats who are dusted with pollen and then groom themselves.
This is a really nasty set of toxins, and within hours of ingestion of a toxic quantity (roughly 4g of pollen), symptoms develop. These typically start with excessive salivation, crying, and then vomiting and diarrhoea. This progresses to difficulty breathing, muscle weakness, convulsions, coma, and ultimately death.
If you think your cat might have been exposed to any of these poisonous plants, give your vet a ring for advice. In many cases, treatment before symptoms appear will give the very best chance of a full recovery.