(Editor's Note: This article was originally published on December 12, 2007. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
There are readily available lists of toxic plants for people, dogs and cats and these lists are repeated over and over again on the internet and in magazines. But as a veterinarian I am usually less interested in whether something is called toxic versus how toxic something actually is, and how likely it is to be ingested/contacted so that poisoning actually occurs. I have been practicing as a veterinarian for over 20 years now, many of those in emergency medicine, and have yet to see a single case of a winter holiday plant toxicity. Yet one of the first plants everyone tends to think of in terms of toxicity, the winter holidays and pets, is Poinsettias. Of all toxic plants these are probably one of the least toxic around . The following article is a brief discussion of some of the toxic plants one’s pets might encounter this time of year.
dogs are always investigating, and sometimes sampling greenery, even if it tastes bad
even cats sometimes eat something they shouldn't
Poinsettias are very common and popular holiday plants in the Euphorbia family (Euphorbia pulcherrima). Nearly every toxic plant list I have seen has this plant on it. Every client I talk to about toxic plants knows this Euphorbia is toxic. Well, ALL Euphorbias are toxic to some degree- they have a milky, irritating sap that helps to heal their own wounds as well as protect themselves from would-be vegetarian dangers. But from a Euphorbia point of view this is easily one of the least toxic in this genus. Dogs that eat Poinsettias may, if they eat enough, get a stomach ache and vomit or develop diarrhea and depression. No cat in its right mind would even nibble on one (cats are finicky like that), but if they did, they probably would drool for a while. And that is probably the extent of this plant as far as toxicity goes. The ASPCA poison control center has few reports of any actual poisoning symptoms from hundreds of calls about exposure to this plant, and therapy consists of keeping the stomach feeling good and withholding food and water for a few hours.
just about every nursery is loaded with these infamous 'toxic' plants this time of year
Christmas, or related holiday cacti in the Schlumbergera family are also on most poisonous plant lists, yet they are perhaps even less toxic than Poinsettias are. These plants are tropical, segmented, flattened plants that bloom in periods of shorter day length (ie. Holiday season) and are named Christmas, Thanksgiving and Easter cacti (all very similar in appearance). As with Poinsettia ingestion, symptoms of poisoning include mild vomiting, diarrhea and possibly depression, rarely requiring any therapy beyond withholding food and water for a few hours. I do not know how bad these plants taste, so I don’t know how likely an animal is actually to chew on them. But again, I have never seen a case of toxicity with these plants.
holiday cacti are usually ONLY sold this time of year
Cyclamens are another common holiday plant and I see these in growing numbers for sale this time of year at nurseries, grocery stores and flower shops. The roots and rhizomes contain a toxic substance known as cyclamin that can cause gastrointestinal upset if eaten in large quantities. But as is the case with many other toxic plants, this is highly unlikely to occur as the bulbs are so bad tasting only the most determined dogs could even eat enough to make themselves sick.
Cyclamens are another popular holiday plant thanks to their brilliant colors
Mistletoes are also potentially toxic holiday plants, though actual ingestion and reported cases of poisoning are rare. Mistletoes are parasitic plants (vines) that can be found in forests throughout the world. There a many different kinds of mistletoe, but only a few plants in the genus Phoradendron are used as Christmas ornaments and are toxic. These plants have a variety of toxic principles, but in actual clinical cases, only depression and vomiting has been reported. So like the above three plants, this cannot be considered a serious poisoning hazard, at least in normal situations. However, it is recommended not to allow dogs exposure to large amounts of this just in case one decided it tasted good and consumed a large quantity.
close up of mistletoe and berries
Christmas or English Holly (Ilex aquifolium) is a common holiday decoration plant which has toxic leaves and berries. Like mistletoes, these plants contain a variety of toxic principles, including theobromine, the same toxin in chocolate, a heart toxin. However there is so little of this toxin in Holly that realistic cardiac toxicity is extremely unlikely, and there are no reports of this in the literature. Most pets that eat Ivy (another bad tasting plant) or the berries either have no symptoms at all, or develop some gastrointestinal signs (vomiting, diarrhea, depression) or, more commonly, do a lot of ‘lip-smacking’ for a while. No deaths have been reported.
Hollies for sale in December
English Ivy (Hedera helix) is actually a fairly toxic plant and is over sold along with Cyclamens or other winter potted plant gifts, though some don't always think of this plant as a Holiday season plant. There are very few reported cases of poisoning of this very commonly planted or potted vine and probably the main reason is it, too, is horrible tasting. All parts of the plant appear to be toxic though berries are probably ingested more frequently than leaves by both people and animals. Gastritis and oral iritation are probably the most common symptoms, but dizziness and coma can occur if enough is eaten (very rare in the veterinary world- I could not find a single case of this happening to a cat or dog). However this is a somewhat more serious potential toxin than most other Holiday season plants so care should be taken if ones owns a dog that likes to chew on everything around, or cats that are notorious for nibbling on house plants. It is probably mostly a concern if you own a vegetarian pet such as a rabbit, tortoise, goat or iguana. But still, even for those animals, poisonings are rarely reported.
Ivy is available year round, but seems particularly popular in winter thanks its hardiness and association with the holidays (... 'the holly and the ivy...')
There have been numerous ‘reports’ and stories about Christmas tree water and toxicities due to pets drinking it. So far as I have learned, there is nothing actually toxic about most conifer saps or needles, but the fertilizers or preservatives added to the water in which the trees sit are serious potential pet poisons. But the trees themselves appear to be nontoxic. If you have pets, it is probably best to put your trees in plain, unfertilized water, or use a large, deep ceramic pot that your pets can’t get into, if you plan on adding fertilizers or preservatives to the water.
Many plants may be toxic to birds, as well as dogs and cats, but there is far less information about avian plant toxicities than there is about dog and cat incidents. As delicate as birds seem, they actually seem to be able to tolerate a lot of plants being nibbled and ingested that would be very noxious or toxic to a dog or cat. This is either due to their very different physiology, or the slow, nibbling way they eat, stopping as soon as something tastes bad or is irritating. The only holiday plant on the list of actual toxicities reported in birds is the ever-present Poinsettia, and those episodes involved mild oral irritation and perhaps some vomiting. I did not learn of a single fatality.
my own bird eating a rose (non-toxic!) in the garden
There are many holiday dangers to pets including certain plant-related food stuffs, ornaments and winter-time dangers such as antifreeze toxicity. But in terms of actual serious winter holiday plant poisons, there are few if any offenders to be overly concerned about. In another article I will discuss the dangers of certain plant-related food stuffs such as chocolate, macadamia nuts and common stuffing ingredients like raisins and onions, all which are much more of a problem for pets, both in terms of likelihood of ingestion as well as actual toxicity. But holiday plants, for the most parts, are not as dangerous as many have made them out to be.