Yes, Purslane is toxic to dogs!
Dogs accidentally consuming the Purslane 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).
Purslane consumption is also toxic to Cats and Horses.
Toxic Principles Of Purslane: Soluble calcium oxalates.
More Info About The Purslane Plant
Scientific Name: Portulaca oleracea
Family: Portulacaceae.
Also known as: Wild Portulaca, Rock Moss, Portulaca, Pigwee, Pusley, Moss Rose.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.