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Sweet Birch
Betula lenta
Sweet Birch (Betula lenta) and Birch trees in general are notable for containing methyl salicylate — an analgesic compound related to aspirin — in high concentrations in the bark, leaves, and especially birch essential oil. Cats are extremely sensitive to salicylates because they lack efficient glucuronyl transferase to metabolise them, making birch oil a significant toxicity risk.
Important Notes
Toxic compounds: methyl salicylate (up to 98% in Sweet Birch essential oil); present in bark and leaves at lower concentrations
Mechanism: cats cannot efficiently metabolise salicylates via glucuronidation, causing toxic accumulation; inhibits prostaglandin synthesis affecting the GI tract and kidneys
Symptoms: vomiting, diarrhea, rapid breathing, weakness, tremors; severe cases cause GI haemorrhage, metabolic acidosis, and kidney failure
Birch essential oil is extremely concentrated and highly dangerous — never apply to or diffuse near cats
Contact your vet immediately if your cat is exposed to birch oil or essential oil products
Potentially Toxic Parts
Root
Bark
Leaf
Possible Symptoms Reported in Cats
Shaking, tremoring, "walking as if they're drunk" (ataxia), collapse, and seizures
Neurological · Not explicitly specified.
Liver failure (and serious organ damage)
Hepatic · Not explicitly specified.
Sore skin, redness, or chemical burns
Dermal · Not explicitly specified in the sources.
Vomiting
Gastrointestinal · Not explicitly specified.
Difficulty breathing or open-mouth breathing
Respiratory · Not explicitly specified.
Lethargy, depression, or dullness
Gastrointestinal · Not explicitly specified.
Excessive dribbling
Gastrointestinal · Not explicitly specified.
Disclaimer: This summary was compiled from multiple sources and is for informational use only. It is not a diagnosis or treatment plan. Toxicity can vary based on the substance, amount, plant part, and individual cat. If you think your cat may have been exposed to a toxic substance, contact a veterinarian right away.