Yes, Eastern Star is toxic to dogs!
Dogs accidentally consuming the Eastern Star 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).
Eastern Star consumption is also toxic to Cats and Horses.
Toxic Principles Of Eastern Star: GI and skin irritants.
More Info About The Eastern Star Plant
Scientific Name: Dianthus spp.
Family: Caryophyllaceae.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.