I am sure there is a federal crime to hit a service dog.
In answer to your question -
http://servicedogcentral.org/content/node/445
(510 ILCS 70/)Humane Care for Animals Act.
(510 ILCS 70/2.01c)
Sec. 2.01c. Service animal. "Service animal" means an animal trained in obedience and task skills to meet the needs of a disabled person.
(510 ILCS 70/4.03) (from Ch. 8, par. 704.03)
Sec. 4.03. Teasing, striking or tampering with police animals, service animals, or search and rescue dogs prohibited. It shall be unlawful for any person to willfully and maliciously taunt, torment, tease, beat, strike, or administer or subject any desensitizing drugs, chemicals or substance to (i) any animal used by a law enforcement officer in the performance of his or her functions or duties, or when placed in confinement off duty, (ii) any service animal, (iii) any search and rescue dog, or (iv) any police, service, or search and rescue animal in training. It is unlawful for any person to interfere or meddle with (i) any animal used by a law enforcement department or agency or any handler thereof in the performance of the functions or duties of the department or agency, (ii) any service animal, (iii) any search and rescue dog, or (iv) any law enforcement, service, or search and rescue animal in training.
Any person convicted of violating this Section is guilty of a Class A misdemeanor. A second or subsequent violation is a Class 4 felony.
(510 ILCS 70/4.04) (from Ch. 8, par. 704.04)
Sec. 4.04. Injuring or killing police animals, service animals, or search and rescue dogs prohibited. It shall be unlawful for any person to willfully or maliciously torture, mutilate, injure, disable, poison, or kill (i) any animal used by a law enforcement department or agency in the performance of the functions or duties of the department or agency or when placed in confinement off duty, (ii) any service animal, (iii) any search and rescue dog, or (iv) any law enforcement, service, or search and rescue animal in training. However, a police officer or veterinarian may perform euthanasia in emergency situations when delay would cause the animal undue suffering and pain.
A person convicted of violating this Section is guilty of a Class 4 felony if the animal is not killed or totally disabled; if the animal is killed or totally disabled, the person is guilty of a Class 3 felony.