A Brooklyn teen who admitted tossing a helpless dog off a roof lost his no-jail plea deal yesterday, after the judge learned the poor animal had to be euthanized.

Fabian Henderson, 19, was set to be sentenced to probation after an October guilty plea to aggravated animal cruelty for the July 18 incident at the Red Hook Houses.

But last week, ASPCA officials said they had been unable to find a home for the pit bull, Oreo, because she was too vicious.

Oreo miraculously survived the six-story fall with broken legs and cracked ribs.

Yesterday, after Henderson was late arriving to court, Justice Cassandra Mullen said she wasn’t honoring the plea deal for probation.

Henderson’s lawyer did not return a call seeking comment.