Fruit trees provide us with shade and nutritious food. What is good for humans is not always good for animals, and some common fruit trees are poisonous to dogs. Some are highly toxic, causing severe symptoms up to and including death. Others are only mildly irritating. Regardless of the level of toxicity, it is important to seek proper veterinary medical care if you suspect your dog has ingested a part of a toxic plant. Supervising your dog and checking your trees against a list of toxic plants, such as the one provided by the American Society for the Prevention of Cruelty to Animals, can prevent your dog from falling ill by eating these potentially deadly trees.
All apple trees, including crab apple trees, are toxic to dogs. These trees are of the genus Malus and contain cyanogenic glycosides, a toxin that transforms into the poison cyanide when processed by stomach acid. The stems, seeds and leaves contain this toxin. The toxin gets stronger when the tree is in the process of changing for autumn.
Similar in effect to apple trees, apricots contain cyanogenic glycosides. The effects of this toxin manifest as dark red mucous membranes, a lack of proper circulation throughout the dog's body, dilated pupils, constricted breathing, shock and, if left untreated, death. Care should be taken to ensure proper help is sought if any part of these trees are ingested by your dog.
The fig tree Ficus benjamina contains proteolytic enzymes and psoralen. Proteolytic enzymes are microorganisms that break down proteins in the body. Psoralen sensitizes the body to light. When a dog brushes up against this tree, the skin becomes irritated. Ingestion of parts of this tree do not cause serious effects, but can lead to an irritation of the mouth, excessive salivation and vomiting.
The lime tree, Citrus aurantifolia, contains psoralens. The essential oils produced by the lime tree are also considered a toxic principle for this tree. Ingestion of the leaves, stems or fruits of this tree can lead to severe irritation, sores of the mouth, enteric distress, depression and a sensitivity to light.
Falling under the genus of Prunus, plum, peach and cherry trees contain cyanogenic glycosides in all parts of their growth. Apricot trees are also part of this genus. The overall effects and warnings are similar for these trees, apricots and apples. Ingestion of any part of these trees should be treated as a severe veterinary medical emergency.