The pair were discovered at their flat in Hanover on Tuesday evening, after a relative saw the bloodied body of one of the victims through a window and rang the emergency services.
Firefighters were called in to capture the dog who was still inside the residence, Hanover police said in a statement.
"Initial examinations by a coroner suggest the 52-year-old woman and her 27-year-old son were killed by the dog," it read.
Police investigations into the incident are continuing, the statement added.
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