Yes, True Aloe is toxic to dogs!
Dogs accidentally consuming the True Aloe 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).
True Aloe consumption is also toxic to Cats.
Toxic Principles Of True Aloe: Anthraquinones, anthracene, glycosides (aloin).
More Info About The True Aloe Plant
Scientific Name: Aloe barbadensis
Family: Aloaceae.
Also known as: Medicine Plant, Aloe, Barbados Aloe.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.