You can now add a description to your horse.
To add the description, go to your stable, select the horse and then click on the horse name (on the bottom of the page, where it shows the horse specialization). A small window will pop up and you will be able to click on Edit description.
To view the description of other horses, find the horse and again click on the name to open the window displaying the description.
The description allows HTML, as long as there won't be people abusing this feature.