Thatcher, then at Manchester City, was handed an eight-match FA ban with another 15 games suspended for two years in 2006 after a challenge which left Portsmouth's Mendes concussed and requiring neurological tests.
However, the FA spokesman also confirmed that an ongoing review of their disciplinary procedures could see a sliding scale introduced to increase punishments for serious offences.
He said: "We are currently reviewing disciplinary procedures with a view to potential changes for next season and a sliding scale for red-card offences is one of the options under consideration."
Fagan was running down the clock as Hull closed out victory when Guthrie, 21, ran several yards to scythe him down by the touchline.
Hull manager Phil Brown urged the FA to take further action against the former Liverpool player, claiming an automatic three-match ban was "insufficient punishment".
Professional Footballers' Association chief Gordon Taylor added that Guthrie's actions were "not acceptable".
Guthrie has since apologised, insisting he is not a dirty player, but Fagan faces at least six weeks on the sidelines.
Guthrie will miss the Premier League clashes with West Ham and Blackburn, plus Tottenham's Carling Cup visit to St James' Park.
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Yorkshire PostCraig Fagan offered legal backing PAUL DUFFEN has pledged Hull City's full support to Craig Fagan should he wish to pursue legal action over the horror tackle that could rule the striker out until Christmas. - 1 hr ago
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