Race horses are not retired.. they are killed. Only those who have performed well on the track, very well on the track, survive. Racing it putting horses into "service" is physically punishing on the horses leading to many physical injuries and I am certain people who invest in them already claim their injuries as losses o. Their taxes. Horses are living beings not mere assests and to allow them to be written off at a faster rate puts them into the category of expendable and lowlier than an oven or washing machine used in a rental property.