Do Evergreen Trees Kill Dogs?

Evergreen trees are trees that keep their foliage year-round. While most people think of pine trees (Pinus spp.) and other conifers when evergreen trees are mentioned, a few more broad, basic types of evergreen trees exist. Broadleaf evergreens are trees with typical flat leaves and include hollies (Ilex spp.) and Eucalyptus (Eucalyptus spp.). Conifers are trees with needle-like leaves, including pines (Pinus spp.) and yew (Taxus spp.). Cycads are trees with fern-like leaves, such as palms and those in the Cycas genus.

Whether an evergreen tree is toxic to dogs depends on which type of evergreen tree the dog ingests and sometimes which part of the tree the dog ingests. Some trees, such as the Northern white cedar (Thuja occidentalis, thriving in U.S. Department of Agriculture plant hardiness zones 2 through 7) are non-toxic to dogs and are used in holistic medicine. Trees such as the American holly (Ilex opaca, hardy from USDA zones 5B through 9) are only mildly toxic, causing vomiting and diarrhea. Still other trees, such as those in the yew family, contain toxins that cause sudden death resulting from cardiac failure. The sago palm (Cycas revoluta, hardy from USDA zone 8B through 11) is deadly enough that only one or two seeds are enough to cause death in dogs.

Because every evergreen tree has a different level of toxicity, it’s important to know which trees you have in your yard. Some trees share common names (such as the cedars) but are of completely different genera and species, and one type may be deadly while the other is not. If your dog shows signs of poisoning after ingesting part of an evergreen tree, seek veterinary medical attention. Bring a sample of the tree to help identify the ingested toxin and treat the poisoning.

The most comprehensive way to make sure your dog doesn’t ingest lethal evergreen tree parts is to make sure you don’t have the toxic trees in your yard to begin with. When choosing new trees, research them beforehand to make sure they’re dog-safe. If you have no say in your yard’s landscaping, limit your dog’s access to lethally toxic evergreen trees. If limiting access is impossible, supervise your dog’s time around these trees to make sure no accidental ingestion occurs. It's also possible to train your dog to avoid potentially lethal evergreen trees in your yard.