It was purchased ten days before in Tennessee. It is legal to ride in Atlanta, but not too smart, IMHO. Hope not too much suffering ...
https://www.11alive.com/video/news/local/horse-collapses-dies-in-downtown-atlanta-days-after-owner-bought-it-in-tennessee-safety-concerns-raised-about-city-riding/85-da5c4d5e-d81e-4e1e-ab58-7179cf75cc43
If he was riding it 10 days from Tennessee, I think I see the problem.