Each county in the State of Texas is hereby authorized to pay all medical expenses, all doctor bills and all hospital bills for Sheriffs, Deputy Sheriffs, Constables, Deputy Constables and other county and precinct law enforcement officials who are injured in the course of their official duties; providing that while said Sheriff, Deputy Sheriff, Constable, Deputy Constable or other county or precinct law enforcement official is hospitalized or incapacitated that the county shall continue to pay his maximum salary; providing, however, that said payment of salary shall cease on the expiration of the term of office to which such official was elected or appointed. Provided, however, that no provision contained herein shall be construed to amend, modify, repeal or nullify Article 16, § 31, of the Constitution of the State of Texas.