The British Horseracing Authority's suspensions effectively rule out all 15 of Godolphin's injected horses for the entire campaign with just four and a half weeks left of the season on their return.
The racing body confirmed the punishment and explained the length of the ban:
The BHA has today informed Godolphin, the owners of the horses in question, that the 15 horses known to have been administered with either Ethylestranol or Stanozolol have been suspended from running in races for a period of six months, with effect from Tuesday, April 9, 2013.
The length of suspension reflects the period beyond which the BHA is confident that the horses in question can have derived no performance related benefit from the administration of these prohibited substances.
Certify, which ended 2012 unbeaten in four runs, was one of seven horses to test positive for Ethylestranol while Opinion Poll was one of four whose blood was found to contain Stanozolol.
More top news
A hacker group who claimed to be behind a cyber attack on Sony Pictures have posted a message online apparently mocking the FBI.
The returns of Benedict Cumberbatch's detective and the X Factor judge were among 2014's most tweeted TV moments in a billion conversations.
A family has issued an appeal to help find their missing pet turkey - in case he gets gobbled up as someone's Christmas dinner.