Ray Paulick has a wonderfully written piece on the issues of labor law for trainers.
The key take away for trainers is this; grooms, exercise riders, hot walkers are all non-exempt hourly employees. These employees are required under Federal Labor Law to be paid overtime if they work beyond 4o hours a week. Additionally the employees are required to have a 1/2 hour unpaid lunch break if they are working more than 8 hours and two 15 minute paid breaks as well.
Should there be a complaint with the US Department of Labor, fines and penalties can be extremely costly yet if violations can be proven to be brought improperly can be obtained.