HORSHUs (HORSe-HUman recombinants) are a hybrid species invented by the artist Drafthorse. They inhabit an imaginary future in which an international agreement and governing body, the København Infertile Sex System (KISS), governs the production and status of genetically engineered human-nonhuman hybrids known as "recombinants" ("recons"), developed as intersterile sexual superstimuli and partners for humans with the aim of controlling human population numbers.

HORSHUs are the largest of the recon species. They have horse-like heads, feet, external genitalia, and tails, but humanlike teeth, torsos, arms, and hands. Skin color is also humanlike, ranging from black to pink. The hands and feet are often contrastingly pigmented, producing darker- or lighter-colored "gloves" and "stockings." The armpits, nipples, penis sheath, penis, anal "donut," sex skin, scrotum, clitoris, and clitoral hood of HORSHUs may also be contrastingly colored. All are richly supplied with scent glands, each with its own distinctive odor. Every HORSHU body exudes a strong, complex perfume, individually compounded of musky, sweaty, fruity, and cheeselike aromas, with a distinctly "skunky" component in males. The composite smell sends an explicitly sexual message that becomes particularly powerful during erection and peaks when a HORSHU breaks into horse-like sweat during orgasm.

Having slightly more than a 50% human genome, HORSHUs are by law citizens of their various countries with full legal rights. Nevertheless, they are by nature sexually submissive, reflecting millennia of their draft-animal ancestors' adaptation to a life in harness. Though rarely masochistic in the strict sense, they relish D&S sex, enjoy being dominated by humans, and are always eager to experience or inflict mild sexual debasement. Ponyplay is a favorite with HORSHUs, and light spanking or whipping is a powerful erotic stimulus for stallions and mares alike.

The acronym HORSHU is generally pronounced "horseshoe," though some (mainly human) social-justice activists hope to replace it with "horse-hue." The pronunciation "whore-shoe" is taboo in polite company, but females find it delightfully degrading in the bedroom.