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good to ultrasound the testicles if an ultrasound machine is available. Then we can check the consistency of the testicles and also measure them with ultrasound to determine total mass. This correlates well with the horse’s ability to produce sperm cells. We can evaluate total mass and make a prediction of potential total sperm production. This is another tool, along with our assessment of daily sperm output,” he explains.
“We also want to palpate both testicles
and assess their uniformity. Any abnormali- ties, such as drastic disparity of size or a soft
or too-hard texture, will often correlate with poor sperm quality and/or lower than expected sperm numbers. Position of the tail of the epididymis should be noted. Normal posi- tion is a caudal orientation (toward the rear
of the horse), but it is not uncommon to find
a 180-degree rotation with no ill effects due
to a twisted spermatic cord. Doing several collections gives us an opportunity to evaluate his behavior, and also to evaluate the penis for normal function and conformation.”
“To be thorough, we also need to culture the semen. We should also process it, just like we were going to ship it out. We need to dilute it or extend it and cool some samples so we can evaluate it at
Mounting the phantom and collecting the stallion
24 and 48 hours (regarding motility, etc.) to see how well his semen ships,” explains Coy.
During or after the breeding soundness exam, if any major issues arise - whether behavioral, musculoskeletal issues, or sperm issues such as lack of numbers, too many defects or poor motility - these can be pursued with further evaluation. “This may require
a reproductive specialist who is well trained in stallion fertility and evaluation. Advanced fertility evaluation can best be handled by a professional who has the training, knowledge and equipment for this,” he says.
“The seminal plasma, or the fluid part of the ejaculate, of sub-fertile stallions has a nega- tive effect on sperm quality. The removal of 95% of this seminal plasma via centrifugation will reduce detrimental effects to sperm qual- ity. This enhances the overall fertility of that horse and allows them to have a satisfactory breeding season,” says Coy.
There are techniques that can be used to concentrate semen or remove seminal plasma, and this can help a lot of stallions. Those with less than optimal sperm motility in fresh and/ or cooled semen can often benefit from further experimentation with different semen extenders
and/or more advanced processing of the semen. “Semen should be processed and extended with different brands and types of extenders, and evaluated for motility after cooling to determine which extender provides the best preservation of semen quality. If a stallion has spermatic defects or viability issues, more advanced techniques can be explored to enhance his fertility.”
This is all the more reason to start the evaluation well ahead of the breeding season to discover any issues that might need some time to resolve. “There are many issues that can be helped, but we need to find out about them before the last minute because it may require time to identify and deal with them. If there
are fertility issues, there are various techniques that can be explored. Some of these new tech- niques have been proven to be very effective in helping sub-fertile horses. For instance, there are products and techniques that are useful in processing the semen of these horses to reduce or eliminate the defective sperm cells and concentrate the viable cells so these can be used in a low-number, low-volume, deep uterine horn insemination technique that enhance a stallion’s fertility,” explains Coy. These have recently been very effective for several stallions.
SPEEDHORSE, March 22, 2013 35
EQUINE HEALTH
Royal Vista Southwest