Researchers develop tools to help castrate horses
Castration of young stallions is often performed at home, but there are risks with the current method that in the worst case can lead to serious complications. Now, researchers at SLU want to improve the method with the help of a new product.
A self-locking band has been developed to facilitate a common castration method in horses. A study investigated the degradation time of the band and its impact on body tissue.
Horses younger than 3 years are often castrated in their home environment. The castration is usually done while the horse is standing up, under the influence of sedatives and local anesthesia only.
Most commonly, a method called ‘castration of the uncovered testicle’ is used, which involves opening up the membranes surrounding the testicle. The membranes are an extension of the peritoneum and opening them creates a small passage up to the abdominal cavity. However, this poses a small risk of abdominal organs escaping through the wound, known as intestinal prolapse, with disastrous consequences for the horse. Before removing the testicles, the funicle (the spermatic cord with its surrounding blood supply and musculature) is crushed with forceps to seal the blood vessels. If the forceps have not crushed the blood vessels sufficiently, this can cause severe bleeding, which can also be life-threatening for the horse.
Researchers at SLU want to develop an aid to reduce the risk of these complications. Today, the product LigaTie is developed for sealing (ligation) of blood vessels and tissue in small animals, including dogs. It works like a cable tie and is made from a material that breaks down and dissolves in the body. By modifying the product to be suitable for larger blood vessels and thicker tissue, it could be used for ligation of the equine funicle. The aim is to make the product so flexible and easy to use that it can be used for standing castrations of stallions, thereby reducing the risk of serious complications such as bleeding and intestinal prolapse.
Before starting clinical studies, the local tissue reaction caused by the band was investigated by inserting several bands under the skin of a number of horses. At set times, tissue samples were taken from the band and surrounding tissue. The samples were examined microscopically and mechanical tests were performed on the tape. The ligaments and surrounding tissue were also examined by ultrasound to monitor the appearance of the ligaments over time.
These studies showed that the tape caused a transient inflammatory reaction similar to that previously described for the same material. However, the bands took longer to dissolve than expected and were still clearly visible on ultrasound examination 4 months after insertion. A major difference was seen in how the bands degraded after being placed under the skin (in vivo) or in a buffer solution (in vitro). Bands degraded in vivo lost their tensile strength and elasticity significantly faster than bands degraded for the same amount of time in vitro. This explained to some extent why tapes that were surgically removed after 10 days had already broken into pieces.
In conclusion, the band causes only a mild and transient tissue reaction in horses, but further research is needed on the strength of the material before the product is ready for clinical trials.
References:
Adolfsson, K.H., Sjöberg, I., Höglund, O.V., Wattle, O. and Hakkarainen, M. (2021), In Vivo Versus In Vitro Degradation of a 3D Printed Resorbable Device for Ligation of Vascular Tissue in Horses. Macromol. Biosci., 21: 2100164.
Sjöberg, I., Law, E., Södersten, F. et al. A preliminary investigation of the subcutaneous tissue reaction to a 3D printed polydioxanone device in horses. Acta Vet Scand 65, 48 (2023).