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Study: South African Swine Vaccine Can Limit Castration Complications

Surgical castration of intact male horses is common throughout the world, but the routine surgery isn't always complication-free. A South African study led by Dr. John Birrell investigated the use of a GnRH vaccine (sold under the name Improvac by Zoetis in South Africa) prior to castrating 19 colts. The study sought to determine if the vaccine could reduce testis size and therefore minimize the risk of surgical complications.

GnRH is an immunocontraception vaccination – it's a birth control that uses an animal's immune system to mount a response against the reproductive process.

The colts were divided into three groups. Two groups received the GnRH vaccine and were castrated 57 and 100 days after receiving the two-part vaccine while the third group acted as a control. The testis of each horse was measured for length, width and height on days 0, 28 and 57 or 100 depending on when the horse was gelded. The horses were also monitored for 10 days after the surgery for complications like swelling, surgical site discharge and depression. The horses also had both their testosterone concentrations and anti-GnRH titers measured.

The GnRH vaccinated colts had no fevers, swelling or lameness after vaccine administration. They also had a decline in testosterone levels after the first vaccination; testosterone was undetectable 28 days after the second dose. The vaccinated horses had a 50 percent reduction in testicular volume prior to castration and they also had no post-surgical complications.

The study team concluded that GnRH vaccine administration reduced testicular size and was helpful in controlling post-surgical complications. They noted that the GnRH vaccine could be used to control undesired behavior in stallions.

Read more at EquiManagement.

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Why Do Some Geldings Act Like Stallions?

Some male horses, even when gelded, can act like intact stallions. These behaviors can cause issues when the horses are turned out or when they are being handled in the barn.

As most stallions are kept only for breeding purposes, the majority of horse owners have no experience with them or their hormone-driven behaviors; eliminating these behaviors is a driving force behind having a male horse castrated.

Gelding a horse removes his testes, eliminating the source of testosterone, but some of the greatest effects of testosterone occur when the horse in utero, where the fetus' testes pump out a plethora of male hormones. This early influence may cause geldings to act like stallions, fighting with other geldings, mounting mares, acting aggressively with people, attacking foals or herding mares.

Interestingly, many geldings that exhibit stallion-like behavior are in their teens, though it's unclear why they act this way more than their younger counterparts. One theory is that a tumor on the geldings' pituitary glands secrete extra hormones. Another theory suggests that the increased confidence and social rank that comes with age may encourage the stallion-like behavior.

Some geldings may act stud-like because they were not gelded completely; they may have a retained testicle that has failed to drop into the scrotum. A blood test can determine if the horse has a retained testicle, which can be removed surgically.

Stallion-like behaviors can include:

Fecal marking. Some geldings will pass manure on other horse's fecal piles as a way of making others aware of his presence. Stallions in the wild do this as well.
Flehmen response. A horse raises his head, curls his upper lip and inhales to better smell mares he is near. This is a harmless action, but can accompany more troublesome actions.
Mounting mares. This can be a dangerous as mounting can injure the mare or the gelding if he is the recipient of a kick.
Fighting. A gelding acting stallion-like may fight off male horses to keep them away from “his” mares, potentially injuring himself or other horses in the process.
Herding or guarding mares. A gelding may continuously move mares away from people or other horses in the field, keeping them just out of reach.
Acting aggressively with people. Anyone working with or near a gelding exhibiting this behavior will be at risk of being bitten, charged or struck, especially if mares are present.

Read more at Horse & Rider.

The post Why Do Some Geldings Act Like Stallions? appeared first on Horse Racing News | Paulick Report.

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