Yes, Eucalyptus is toxic to dogs!
Dogs accidentally consuming the Eucalyptus plants can show the following clinical symptoms: Vomiting, Prolonged Depression, Incoordination, Hypersalivaton, Sleepiness Or Excitation, Dilated Pupils, Low Body Temperature, Low Blood Pressure, Coma, Seizure And Death (In Rare Cases).
Eucalyptus consumption is also toxic to Cats and Horses.
Toxic Principles Of Eucalyptus: Essential oils: eucalyptol.
More Info About The Eucalyptus Plant
Scientific Name: Eucalyptus species
Family: Myrtaceae.
Also known as: Many cultivars.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.