The Cryptorchid Project: Identification of genes regulating cryptorchidism in horses
Project overview
Participants
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Short summary
Horses with cryptorchidism, an incomplete descent of the testicles, are often referred to as geldings. These horses are at increased risk of developing testicular tumors and often have hormone production equivalent to that of a normal stallion.
This means that they usually have fully developed stallion behavior, which is undesirable if the individual is not considered suitable for breeding.
Cryptorchidism is common in horses, affecting an estimated two to eight percent of all stallions. In most breeding associations, cryptorchidism means disqualification for breeding, but for some performance-oriented breeds, exceptions are made if the stallion is a successful competition individual.
Owning a gelding means a financial loss for the horse owner, as castration is a more complicated procedure. The cost can sometimes be more than 10 times higher than for a normal castration. For the horse, it means heavier sedation, a longer recovery period, and the risk of complications such as swelling, bleeding, intestinal prolapse/hernia, inflammation of the vas deferens, and peritonitis. Some geldings retain stallion behavior after the operation due to remaining hormone-producing tissue. There is also an increased risk of tumor formation in the testicles of cryptorchid horses. This is believed to be due to the testicles being exposed to high temperatures inside the body, which disrupts rapid cell division in the testicles.
The first step in this research project is to calculate the heritability of cryptorchidism. Once this has been done, we want to move on to finding out which genes are involved in certain horses developing cryptorchidism and becoming geldings. We want to answer this question by conducting a genome-wide association study (GWA), which means that, with the help of horse owners and veterinary clinics, we will collect blood and hair samples from a large number of geldings and control horses (case-control design), which we will then test on a Single Nucleotide Polymorphism chip (SNP chip).
Using this methodology, we can identify gene regions associated with cryptorchidism. This is relevant for future horse breeding work to avoid cryptorchidism and may also give rise to candidate genes involved in cryptorchidism in both horses and humans.
Sample collection
If you own a horse affected by cryptococcosis, please feel free to contact us for more information.