Section 14. All neat cattle and other domestic animals, which are affected with, or have been exposed to, foot and mouth disease, shall be destroyed when, in the opinion of the director, the public good so requires, and their carcasses shall be buried or otherwise disposed of. An order for killing and for the disposal of carcasses shall be issued in writing by said director, and may be directed to an agent, an inspector, or other person. The said director shall also issue such directions for the cleansing and disinfection of buildings, premises and places in which foot and mouth disease exists or has existed, and of property which may be on or contained therein, as in his opinion may be necessary or expedient. Any property on such premises which may be, in the opinion of the director or of his agents, a source of contagion may be destroyed by order of the director. The necessary expenses incurred in carrying out this section may be paid from the annual appropriation for the extermination of contagious diseases among domestic animals. The director may appoint persons to make appraisals on live stock and other property the destruction of which is ordered under this section, and fifty per cent of the full value of such live stock and other property, as determined by the appraisal, may be paid from the annual appropriation aforesaid. If the United States government makes an appropriation for payment of a certain portion of the value of any animals and property destroyed under this section, the payment by the commonwealth for such animals or property shall be limited to the difference between such portion and the full value thereof determined as herein provided, which shall not be in excess of fifty per cent of such value.