I'm not sure that I'm very good with clues but here goes -
5 "Sadly" means make an anagram of the words indicated. Think about the "long gone".
44 The two words begin with S and B. The whole gruesome article was not used on horses but the second word on its own has a very specific horse connection. Substitute "B" for "Second class" and use Chambers - I doubt that you will have met the word you construct.
Thank you for 99 - got it. Did it feature with Old Lob in the Beacon Readers? That dates me.