510 ILCS 50/13
The Department shall cooperate with any commissioner or other officer appointed by the United States authorities, in connection with carrying out any provision of any United States Statute providing for the suppression and prevention of contamination or contagious and infectious diseases among animals, in suppression and preventing the spread of contamination or contagious and infectious diseases among animals in this State.
The inspectors of the Animal Health Division of the United States Department of Agriculture and the Illinois Department of Agriculture have the right of inspection, quarantine and condemnation of animals affected with any contamination or contagious or infectious disease, or suspected to be so affected, or that have been exposed to any such contamination or disease, and for these purposes are authorized to enter upon any ground or premises. Such inspectors may call on sheriffs and peace officers to assist them in the discharge of their duties in carrying out the provisions of any such statute, referred to in the preceding paragraph, and the sheriffs and peace officers shall assist such inspectors when so requested. Such inspectors shall have the same powers and protection as peace officers while engaged in the discharge of their duties.
510 ILCS 50/13