When you look at the gender displayed in the horse stall, you might see a label other than ‘雄’ (stallion) or ‘牝’ (mare), such as ‘セン’. Many people starting horseback riding have wondered, ‘What is a ‘Sen’ horse?’ In this article, we’ll explain the differences based on horse gender and the benefits of geldings!
Horses Have More Than Just Male and Female!
Do Horses Have Three Genders?
Seeing the title, many might be surprised and wonder, ‘Are animals’ genders only male and female?’ Of course, horses are no exception—when born, they are only male or female.
However, in racehorse information and stable stalls, you’ll see horses labeled as ‘stallion’ (牡馬) or ‘mare’ (牝馬), and also horses labeled as ‘geldings’ (セン馬).
Actually, a gelding is a castrated male horse. But why is it called differently from a stallion? Before considering that, let’s take a quick look at the characteristics of stallions and mares.
Size Difference Between Stallions and Mares
Humans tend to have taller averages in men than women, and the same applies to horses. On average, stallions are slightly larger—Thoroughbreds, for example, have an average height of 161cm and weight of 468kg, while mares average 159cm and 448kg.
Stallions aren’t necessarily muscle-bound, but they do tend to have more muscle mass. In racing, stallions usually carry about +2kg weight allowance. While that might seem significant, considering the size difference, this is roughly equivalent to 200g for humans.
Which Animal Has a More Fiery Temper?
As with all animals, individual personality varies greatly—regardless of gender difference. Typically, it’s said that stallions are more aggressive because they historically needed to defend their herd and territory. Nevertheless, some say mares can have more emotional swings, especially before races, which can tire them out and impact performance.
Are There Race Limitations Based on Gender?
In equestrian sports, there are generally no restrictions based on the horse’s gender for entry. However, in racing, some races like the Ouka Sho and Queen Elizabeth Cup are exclusive to mares. Conversely, there are no races restricted only to stallions.
Geldings face more restrictions—of course, they cannot participate in mares-only races or some classic and GI races, which have traditionally been used to select breeding stallions. This stems from a history where such races also served as breeding evaluations. Unbred geldings are usually excluded from these events.
What Are the Benefits of the Third Gender: Geldings?
Calmer Temperament
After understanding the differences between stallions and mares, let’s explore the advantages of geldings, which are considered as a middle ground.
Firstly, castration reduces testosterone levels, which in turn calms the horse’s temperament. This makes it easier for handlers to give instructions. Also, since they aren’t naturally aggressive or excitable, variability in their mood is minimized.
Moreover, although mares suffer from estrus cycles managed by medicine, stallions can become unsettled or less focused when near hormonally active mares. Geldings tend to be more stable and consistently perform at their best.
Flexible Body and Improved Mobility
Stallions are often bigger and muscular, but they tend to have less body flexibility due to high testosterone levels, which cause their muscles to develop larger and denser, reducing their range of motion.
The advantage of geldings is that, with lower testosterone and more dominant estrogen, their flexibility improves, making their movements more graceful. This also enhances their performance ability and reduces the risk of injuries, benefiting both horse and rider.
Are There Any Downsides?
While geldings seem advantageous, are there drawbacks to castration?
The main disadvantages from a human perspective include ① inability to become a stud (breeding horse) despite excellent performance, and ② exclusion from some major races like the Japanese Derby or Satsuki Sho.
From the horse’s perspective, the biggest concern is operation risks. Although veterinary techniques and equipment have improved significantly, there’s still a possibility of postoperative complications like infections or anesthesia shock. Also, hormonal shifts after surgery can cause temporary symptoms similar to menopause in humans.
Some horse owners feel it’s unfair or cruel to operate on a healthy horse, fearing health issues or risking losing competitiveness. However, a calmer temperament and suppressed estrus can make life easier for the horse. Castration also prevents unintended pregnancies in stable environments.
If facing this choice, carefully weigh the benefits and risks to ensure the future welfare of your horse!
Famous Geldings
In the world of horseback riding, geldings are common. Many of the horses that won medals at the 2021 Tokyo Olympics were geldings. However, in Japanese racing, stallions are still more prevalent. As a result, the stronger horses tend to be stallions. Nonetheless, some geldings have left a significant mark as legendary horses, such as:
Red Davis
A legendary horse that, although not winning major races, famously defeated Orfevre, a Triple Crown winner. Notably, Red Davis was castrated before debut, which was a big talking point at the time.
Legacy World
While geldings rarely get the spotlight, Legacy World broke through with a victory at the Japan Cup, becoming the first gelding trained in Japan to win a G1 race. He also placed second at the Arima Kinen, showcasing exceptional performance.
Marvelous Crown
Famous for his fiery temper during training, Marvelous Crown calmed down after castration. He too won the Japan Cup as a gelding, following Legacy World as a notable G1 winner.
Summary
Castrating stallions into geldings not only calms their temperament but also reduces injury risks, offering many benefits. Despite the small number of geldings in Japanese racing, those with outstanding achievements are worth noting. Since geldings are common in equestrian activities, next time you visit a stable, try to observe the gender of the horses!