11. Both mules and hinnies can be either male or female, but they are almost invariably sterile. 12. Thus, a hinny is restricted to being about the size of the largest breed of donkey. 13. Female hinnies and mules are not customarily spayed, and may or may not go through estrus. 14. Namely, in China, in 1981, a hinny mare proved fertile with a donkey sire. 15. When the drake is a pekin, the offspring tend to be smaller and are called hinnies . 16. "Hinny " is a term of endearment in the dialects of the Newcastle area. 17. Male hinnies and mules are usually castrated to help control their behavior by eliminating their interest in females. 18. Other than size, some additional minor differences occur that can be used to distinguish between mules and hinnies . 19. DNA testing revealed the foal has a mixed karyotype hybrid like the Chinese hinny offspring " Dragon Foal ." 20. A hinny is a cross between a stallion and an ass; it has a bushier tail than a mule.
