Is there a limit as to how long these comments stay with a horse?
I recently started entering comments for horses, to give me an easy way to figure out which location, what type of surface and what distances they seem to prefer,
I can’t remember which horses I’ve already entered comments for but, every horse I’ve checked since I started, the Owner Comments are blank.
Just curious to see whether I’m wasting my time entering these comments.
I have always used comments with my horses. Just checked randomly and they are all still available. The only time they have gone missing is when I forgot to click the submit button at the bottom, which I do more than I should 
Owner comments are never wiped (technically they should be on sale, but that’s not implemented).
I never use comments, but I’ve definitely picked up horses with comments several years old from prior owners. So definitely can confirm they are never wiped.
I keep a height chart in my owner comments. So far so good. Just remember to save them before you navigate away from the page.