https://www.the-tls.com/regular-features/mary-beard-a-dons-life/making-your-horse-a-consul-blog-post-mary-beard
One of the best known bon mots of a Roman emperor is Caligulas quip that he fancied making his favourite racing horse a consul (he didnt actually do it, he just said he planned to). Traditionally this was seen as a sign the man was completely deranged. More recently it has been interpreted as a bit of imperial banter, against the senate, whose point was missed. What the emperor was really saying was You senators are such a useless lot that this horse would do a better job. There is something in that, I think (some of the worst imperial barbs in general might sometimes have been unrecognised irony). But I have been looking a bit harder at emperors and their favourite horses over the past week, and see other things in it too.
The consul quip is only one of the excesses reported of Caligula and this particular horse (Incitatus or Full Speed). The emperor is also reported to have stationed soldiers around its stables on the night before the races to ensure that there was quiet and it got a good nights sleep. He also gave it a marble stall, an ivory manger, its own slaves, etc etc. (You can find some of this in Suetoniuss Life of Caligula, chapter fifty-five). And he wasnt the only emperor to go to similar lengths. Lucius Veruss favourite race horse Volucer (Flyer) used to visit him in the palace, and was fed on nuts and raisins instead of barley; and Verus had a little gold statue of the animal made, which he carried around with him in his luggage. And Commodus had his favourite too, which on one occasion did a lap of honour in the Circus Maximus with its hoofs painted gold. (Ominously Commoduss favourite was called Pertinax (True Grit), which was also the name of the man who replaced him on the throne, after his assassination.)
In fact, modern scholarship suggests Caligula probably wasn't really nuts... that it was more of a post-mortem propaganda campaign. See the work by Alois Winterling