As the 2018 breeding season is quickly approaching, we at Colt Ventures are excited to see what the year will bring for High Brow Cat. We saw incredible numbers in 2017, and we can’t wait to see those foals this year! High Brow Cat produced 108 pregnancies this season and an additional 70 embryos were frozen from aspirations through the ICSI procedure. 
     In preparing for the upcoming season, we sat down with Justin Ritthaler, DVM, Weatherford Equine, who helped shed some light on High Brow Cat’s success in 2017 and what he thinks the future will hold for “Cat” as we continue to attract many of the industry’s top performing and producing dams.


Question: High Brow Cat has produced 100+ embryos every year with ICSI since Colt Ventures started with the procedure in 2013. What are your thoughts about these numbers for 2017 as well as the overall consistency of his conception rates with ICSI? 

Dr. Ritthaler: “This was, again, another very successful season for Cat. With several years of using ICSI to generate a high number of pregnancies, it provides a good testimony for the success of the procedure.”  

Question: What are some common misconceptions about ICSI? Have you seen any negative long term effects on mares with ICSI? 

Dr. Ritthaler: “The most common misconception I hear among mare owners that are not using ICSI is that there are concerns about it affecting the reproductive health of the mare. We do not see any adverse effects from aspirating oocytes. The vast majority of the mares aspirated at Weatherford Equine are also bred to flush embryos, and also put into foal to stallions with available frozen semen or fresh semen. We will switch back and forth between ICSI and routine embryo flushing and breeding depending on the mare’s available follicle numbers. We have not seen any change in embryo flush rates or pregnancy rates of mares that have undergone an oocyte aspiration.” 

Question: How do you think ICSI is going to change or impact the breeding industry in regards to extending the breeding career of stallions such as Cat, the leading cutting horse sire? Also, how does it extend the breeding career of top broodmares?

Dr. Ritthaler: “Cat has been instrumental in proving how the ICSI procedure will extend the breeding life of a stallion. Without the procedure, we would not have seen a fraction of the foals born sired by High Brow Cat as we have since Darren started using it in 2014. With the success that High Brow Cat has experienced as a stallion with the ICSI procedure, we are starting to see more stallion owners promoting ICSI to increase the productivity of their stallions and extend limited supplies of semen. Use of ICSI is growing in all breeds of horses, but in our practice, the cutting horse industry is still providing the most mares for the procedure.  The cutting industry is starting to fully embrace it as a valuable breeding technique as the mare owners become more educated about it.”

Question: “What type of mares are good candidates for ICSI? How can ICSI increase pregnancy rates for mares with fertility issues?

Dr. Rithaller: “Any mare is a candidate for ICSI. There are many mares with reproductive problems that can only produce pregnancies with ICSI. But the other category of mares are the ones breeding to stallions of limited semen availability, and for those situations any mare is a candidate. We have produced pregnancies from ICSI derived embryos from mares 3-25 years old.”

Question: What advancements or additions have you seen in regards to ICSI recently?

Dr. Ritthaler: “There haven’t been any advancements, so to speak, in the actual procedure. I will say that with the opening of EquiEmbryo in North Fort Worth by Dr. Choi, we have been able to fine tune the logistics of getting oocytes to him and embryos back from him for implantation. Dr. Choi is one of the most regarded veterinarians in his field. He proved this season that his new facility in Fort Worth is very capable of handling a high number of oocytes and with a high success rate of producing ICSI derived embryos. Dr. Choi positioned himself there to be close to our high population of valuable breeding animals, as well large airports so that his facility can receive and ship to other areas of the country. We have been very happy with his success and expect to continue using his laboratory in the future.”

Question: What are advantages of freezing embryos with ICSI? What are the associated costs with a frozen embryo? Have the costs associated with ICSI decreased since it was first introduced?

Dr. Ritthaler: Freezing embryos has allowed some of our mares the chance to only get aspirated when we run out of frozen embryos to transfer. By decreasing aspirations, we are also able to decrease overall costs for the mare owner. Many clients are also interested in banking as many embryos as they can from some of their aging mares. In doing so, we can transfer the embryos when the mare becomes unable to flush embryos, when she becomes too old to be aspirated, or when the mare passes away. Another reason for freezing embryos is that the procedure can be done any time which can accommodate the mare’s show schedule or other time conflicts.

For more information on ICSI and breeding to High Brow Cat email breeding@coltventures.com