Christmastime Plants

Chapter 37 Christmastime Plants

Christmastime brings with it a large assortment of plants that are used for decorative purposes throughout the holiday season. Because of their novelty, when they seasonally appear in the house, and because these plants are kept primarily indoors, there is increased potential for household pets to be exposed to them. Both dogs and cats have been known to chew on houseplants, with the primary difference between these two species being the amount of plant material ingested. Although cats often only nibble on a few leaves, many dogs will devour the entire plant, including potting soil, if the opportunity arises. Other indoor pets, such as birds and rabbits, may similarly be exposed to these decorative plants. Fortunately, few of the plants common to the Christmas holiday have the potential to cause serious or life-threatening signs in pets if ingested, and the majority are generally expected to cause at most mild gastrointestinal upset.

When dealing with an exposure of a pet to any plant, it is important to determine the identity of the plant (ideally genus and species name) and whether any plant care products (especially systemic insecticides) may have been applied to the plant or soil.


Mechanism of toxicity

Amaryllis and other members of the Amaryllidaceae family contain phenanthridine alkaloids, such as lycorine and tazetine.1 The alkaloids are primarily concentrated within the bulb and leaves where they can be present in concentrations up to 0.5%. Lesser amounts of alkaloids are present in the bulbils and flowers. Lycorine, the principal alkaloid responsible for clinical effects, is a centrally acting emetic, and various other alkaloids have cholinergic, analgesic, hypotensive, and cytotoxic effects. In most pets, chewing on or ingesting leaves generally only causes mild gastrointestinal upset, and ingestion of parts of the bulb may lead to more severe signs.1,2

Clinical signs

Mild to moderate vomiting, diarrhea, anorexia, and hypersalivation are the most common signs seen when animals ingest leaves, flowers, or small amounts of amaryllis bulb.2 More severe gastrointestinal upset may be manifested by restlessness, tremors, or dyspnea.1 Less commonly, hypotension, sedation, or seizures may occur, especially if large amounts of bulb material have been ingested.2 In humans asthma has been associated with exposure to amaryllis, but this has not been reported in small animals.3

Minimum database

Because protracted vomiting and/or diarrhea may result in dehydration and electrolyte abnormalities, animals showing severe or prolonged gastrointestinal upset should have their hydration and electrolyte status monitored. Hepatopathy has occasionally been reported to be associated with amaryllis ingestion,2 so measurement of baseline and 72-hour liver enzyme values may also be indicated in more severe cases. Complete evaluation of hematological and serum biochemical values is usually prudent for aged animals or those with preexisting health problems.



Christmas cactus (Schlumbergera truncata), also known as crab’s claw cactus, is a member of the cactus family that is native to the jungles of Brazil.4 These popular cacti have flattened, spineless branches tipped with flowers that range in color from red to pink, white, yellow, or orange.

Mechanism of toxicity

In humans exposure to Christmas cactus has occasionally been associated with type 1 hypersensitivity, resulting in urticaria and rhinoconjunctivitis.5 However, in dogs and cats, the primary clinical effects are due to irritation of the gastrointestinal tract from ingested leaves.4

Clinical signs

Clinical signs following ingestion of Christmas cactus include vomiting (with or without blood), diarrhea (with or without blood), depression, and anorexia.4,6 In cats ataxia has occasionally been reported as well.6 These signs are generally mild and rarely require more than withholding of food and water to allow the digestive tract to recover. Aged animals or animals with preexisting health conditions may experience more moderate to severe signs requiring veterinary intervention including the use of antiemetics or antispasmodics, and correcting any hydration or electrolyte abnormalities.


Mechanism of toxicity

The seed cones from some species of Juniperus have been used as food by wildlife and humans, and seed cones and foliage from other Juniperus species have been used medicinally for their diuretic and uterine stimulant effects.1 Needles, branches, and bark of many of the evergreens used as Christmas trees contain monoterpenes and diterpenes and a variety of essential oils. Some of the terpenes and essential oils have been demonstrated to produce fetal deaths and malformations in laboratory rodents.7 In livestock, ingestion of green or dry needles, bark, or budding branches of various evergreen plants has been associated with stillbirths, abortions, and other reproductive disorders.1 Reproductive effects in livestock generally require ingestion of relatively large amounts of plant material over days to weeks. In small animals, where relatively small amounts of evergreen material might be ingested and chronic ingestion is unlikely, reproductive effects would not be expected. Concentrated essential oils of a variety of evergreens (e.g., thujone from cedar oil) have been shown to cause CNS effects, including seizures in animals,8 but exposure to the level of essential oils in Christmas tree material is unlikely to cause significant CNS effects in pets.

The mechanisms of action for the majority of the constituents of Christmas tree evergreens are not known. Some Juniperus species contain podophyllotoxin, which binds tubulin, resulting in arrest of cell division in metaphase and that may contribute to the teratogenic and reproductive disorders seen in livestock ingesting these plants.1 Some volatile oils in evergreens have been demonstrated to induce hepatic P450 enzymes, which can alter xenobiotic metabolism.9 In small animals, ingestion of plant material would be expected to cause gastrointestinal upset, either through mechanical irritation or irritation from terpenes or essential oils. Rarely, ingestion of large quantities of evergreen needles, bark, or cones might result in gastrointestinal foreign body obstruction.

Sep 11, 2016 | Posted by in SMALL ANIMAL | Comments Off on Christmastime Plants
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