Can i be sued for a accident that wasn't my fault because of a horse in road?

You can be sued for anything. The question is whether or not te plaintiff will prevail on the merits of the action. You haven't provided enough information to give an answer. Were you issued a ticket and found at fault? Were you found guilty of the charge? Who is suing you? Is an insurance company suing you to get back damages it paid out? What were the circumstances of the incident?