A horse boot has an upper that includes substantially independent side walls that may be flexed inward or outward as needed to conform to the shape of the hoof to which the boot is fitted. The upper has no front portion and is preferably integral with a polymeric horseshoe with free heel ends defining a gap. A cantilevered resilient frog support connects the heel ends of the horseshoe, thus providing a spring-like structure tying the heel ends together. The interior surface of the horseshoe has a grid of interconnected recesses and the upper has lateral perforations adapted to receive glue material. The boot is fitted to the hoof by lining the surfaces of the upper and the horseshoe with glue and holding the boot in place while the glue hardens, thereby securing the boot to the hoof. The entire fitting process may be carried out in a few minutes and the boot remains in place essentially without maintenance.