Synopsis As Introduced Amends the Landlord and Tenant Act. Prohibits a landlord or lessor from refusing to rent to, deny housing to, or impose conditions on a lessee or tenant based on the breed of a dog or dogs in residential housing that contains more than 3 units of housing. Provides that nothing in the Act affects the ability of a unit of local government to enforce provisions of the Animal Control Act regarding a dangerous dog or vicious dog. Provides that if a lessor or landlord violates these provisions, upon request of the affected lessee or tenant, the Illinois Housing Development Authority must investigate the matter. Provides that if the Authority finds that a lessor or landlord has violated the Act, it must commence an action or proceeding in the circuit court of the county in which the premises are situated to stop the violation either by mandamus or injunction. Provides that the amendatory Act applies to a renewal or modification of residential leases that contain more than 3 units of housing after the effective date of the Act and for new residential leases entered into after that date.