Yes, male donkeys possess testicles, which are reproductive organs. They are a fundamental part of the male donkey’s anatomy, serving the dual purpose of reproduction and hormone production. The presence of these organs is an indicator of an intact, or uncastrated, male donkey. This anatomical structure is shared across the entire equine family, which includes horses and zebras.
Understanding Donkey Terminology and Anatomy
An intact male donkey is properly referred to as a Jack or Jackass, while a female donkey is called a Jenny or Jennet. The donkey species is scientifically designated Equus asinus. The testicles are paired, oval-shaped glands located externally in the inguinal region, enclosed within a protective sac called the scrotum.
These testicles are typically visible, hanging between the rear legs, although donkeys can sometimes retract them closer to the body. Anatomical studies show that while the overall structure is similar to that of a horse, the donkey’s testicles and associated epididymis are generally smaller and lighter.
The Biological Function of the Testicles
The testicles have two primary biological functions: the production of the male sex hormone, testosterone, and the generation of sperm, a process called spermatogenesis. Testosterone is the central driver of male reproductive behavior and physical characteristics, influencing everything from muscle development to temperament. The concentration of this hormone is positively correlated with the total volume of the testicles and the total sperm concentration.
Spermatogenesis is the process that creates the male gametes necessary for reproduction, which occurs within the seminiferous tubules inside the testicles. Donkeys are particularly efficient at this process, resulting in a very high daily sperm production rate. These biological functions are the source of the strong reproductive instincts and typical male behaviors seen in Jacks, such as frequent vocalization, marking territory, and displaying aggression toward other males.
Behavioral Management Through Castration
Surgical castration is a procedure frequently performed on male donkeys. This intervention is a common management tool used to control the strong, instinctual behaviors driven by testosterone. A castrated male donkey is given the specific term Gelding.
The primary reasons for castration are to mitigate aggression and sexual behavior, making the animal safer and easier to handle. Removal of the testes significantly reduces the production of testosterone, which in turn diminishes aggressive tendencies, excessive braying, and the instinct to mount other animals. While castration may not fully reverse behaviors established in an older male, performing the procedure on younger donkeys helps prevent these unwanted traits from developing. This change in temperament allows geldings to integrate more smoothly into a herd and makes them more suitable as working or companion animals.