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Veterinarian discusses stallion castration considerations

by Wyoming Livestock Roundup

            Most young male horses are gelded unless destined for a breeding career. Dr. Peter Sheerin of Nandi Veterinary Associates in New Freedom, Penn., says there are two popular ways to castrate horses.  

“Some veterinarians prefer to anesthetize them and complete the procedure on the ground, while others prefer horses to stand,” he says. “There are pros and cons to both methods.”

 “With the standing method, a veterinarian avoids potential risks with anesthesia. But, it is important to use proper sedation and local anesthetic, such as judicious use of lidocaine. Veterinarians don’t want the horse to be feeling much around the area when they are doing the surgery or there is risk of being kicked,” Sheerin adds.

            “I complete all my castrations with the horses lying down – just as personal preference,” he continues. “The other thing I like about using anesthesia is the horse is down, and if I need to explore something I can do it more readily.”

            “On the flip side with a standing castration, a veterinarian can know right away whether there are two testicles there,” Sheerin notes. “If a person is comfortable doing both techniques, the choice can be made on a case-by-case basis.”

Regardless of the method, there are certain standard treatments which also take place during castration, such as vaccinations.

Care after surgery

            Pain management is important after surgery.  

“A veterinarian may prescribe non-steroidal anti-inflammatory medication for a few days to help reduce pain and inflammation,” Sheerin explains. “The biggest cause of excessive swelling is due to a horse not moving around as much as he should. If he’s in pain, he’s not going to move.” 

            It is important to keep swelling to a minimum. 

“I tell clients to keep the horse confined for the first 12 to 24 hours so bleeding is well-clotted,” he says. “I recommend not allowing the horse to run around at first or his heart rate and blood pressure will rise, and early clotting may increase the risk of bleeding.”

            After this time period, the horse needs to move.  

“If he is standing around feeling sorry for himself, make him exercise at a trot for at least 10 to 15 minutes a couple times a day,” says Sheerin.

Possible complications

            One of the most common complications from castration is hemorrhaging.  

“This may occur due to too much tension when emasculators are applied to cut through the cord above the testicle, or because a vessel didn’t get crushed enough to clamp it off,” he explains.

            Treatment for a hemorrhage will depend on how seriously the horse is bleeding.  

“If it’s simply dripping, veterinarians will usually just monitor the bleed because it should stop in a few hours,” Sheerin continues. “If it starts streaming after the horse gets up, we generally give it a little time and if it doesn’t slow we need to go in and find the source of bleeding.”

He adds, “The streaming vessel must be clamped or ligated again to halt it.  Some practitioners do it while the horse is standing, while others prefer to lay the horse back down and find it that way.”

            Another possible complication would be infection of the remaining spermatic cord.  

“Castrations done out in the field are not sterile procedures,” Sheerin states. “There is always a chance of contamination. If infection develops in the spermatic cord, the horse will spike a fever and go off feed.”

He continues, “The veterinarian should examine the surgical site and detect the problem based on palpation, white blood cell count or ultrasound. For treatment, the horse must be anesthetized again and the section of cord removed, to get rid of the infection. The horse is put on systemic long-term antibiotics for several weeks.”

            The most common complication is excessive swelling in the sheath.

 “If swelling in the scrotum is detected, where the testicles were, this is something to keep a close eye on. It could be due to a hematoma, infection or hernia with some of the intestines starting to come through the incision,” he says, noting all of those possibilities need veterinarian attention.

“It’s important during surgery to leave adequate openings for drainage,” Sheerin explains. “The incisions for the testicles to come through need to be large, and there will be more swelling if incisions are too small.”  

            He notes one of the most serious complications seen with a hernia is the prolapse of intestines through the incision. Although rare, it can be fatal. Sheerin shares owners should keep a close eye on horses, especially after the veterinarian leaves. 

Castrating foals

Young horses tend to be more prone to scrotal hernia at castration, which is one disadvantage to castrating foals.

“The surgery itself is much easier on them when they are younger,” Sheerin notes. “However, as they get older, the bigger the testicles and the spermatic cordare, so there is greater chance of bleeding. Additionally, the surgery is more stressful and traumatic.”

            A foal bounces back quickly after the surgery, compared to older horses, and the  mare helps exercise him as they move around the pasture. This eliminates the need to make the horse move forcibly. 

            “Horses castrated as foals generally end up being a little taller and finer-boned than horses cut later in life. The stallion’s long bones stop growing sooner when he reaches puberty. This is all related to testosterone and the closing of the growth plates,” Sheerin notes. 

            Whether horses are castrated as foals or older is usually owner preference. For management, training and behavioral issues, there are many advantages to castrating young. Colts and fillies can be managed together instead of in separate groups, for instance, and young geldings are easier to handle than young stallions.

            Heather Smith Thomas is a corresponding writer for the Roundup. Please send comments on this article to

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