Stem cell therapy may sound futuristic, but it’s becoming much more common when dealing with athletic injuries in horses.

If your horse has ever had a tendon injury or related problem, your veterinarian may have suggested stem cell therapy. Also called regenerative medicine, the use of stem cell therapy is expanding in equine medicine. These cells were discovered in the early 1950s and first used in humans in 1968. Today, they’re routinely used in human cancer and joint replacements, and over the last decade, in horses too.

Types of Stem Cells

There are many types of stem cells, and they’re categorized by the developmental stage of your horse. The main ones you will want to understand are early stage stem cells and adult stem cells.

1. Early stage stem cells (embryonic/fetal) have great potential, but there are currently no commercial options available because of several factors, including bioethics, the expense of harvesting/handling them, and most importantly, the difficulty in controlling their action. These cells often turn to tumor cells.

2. The cells we use in equine treatment are adult stem cells. They include cells harvested from umbilical cord blood from a newborn foal as well as fat, bone marrow and blood from adult horses. There are dozens of equine stem cell kits on the market.

Umbilical cord blood (UCB) – To harvest these cells, the placenta is gathered up after the foal is born and hung up to allow gravity to force the blood down for collection. UCB is then evaluated at the lab and frozen, with the option of using it years later on the same horse in the event of an injury (e.g. bowed tendon). Stem cells and blood delivered from your horse to the same horse is an autologous transfer, while cells delivered from your horse to a neighbor’s is known as an allogeneic transfer. Allogeneic transfers of UCB have been used for years in human cancer patients and were recently used to treat a laminitic horse.

Fat and bone marrow – These can be harvested through surgery, then filtered and injected the same day back into your horse. Another option is to have the harvested cells sent to a lab first to be cultured in an attempt to increase stem cell numbers and, after two to three weeks, go back and inject them into the injury site.

Blood – Blood can be harvested from your horse much like a single blood draw for a Coggins test. The blood is processed in a centrifuge, removing cells (platelets), and then you inject the platelets into the injury. This process is called PRP (Platelet Rich Plasma) and the more concentrated the number of platelets placed into an area, the more stem cells in that area multiply. A five times increase in PRP cells can produce a seven times increase in stem cells to that area.

PRP is the most popular stem cell therapy because it involves no surgery, is the most economical, and can be done on site at the time of the blood draw. It also provides a large volume of therapeutic injections. PRP is now routinely added to fat or bone marrow stem cells because it increases healing actions above using fat or bone marrow alone. PRP is full of growth factors that coordinate stem cell action.

The future of stem cell therapy The wave of the future regarding PRP, fat/ bone marrow or UCB will be under FDA control. Both the AMA and AVMA have been advised of this fact. Whether allogeneic stem cells will be allowed in horses is not clear. Different companies have different harvest techniques, and there is currently no standard as to what cultured stem cells do or do not do in a horse. The quantity of stem cells needed in a site to help healing, along with which type of stem cell source is best, is not known.

PRP is now routinely added to fat or bone marrow stem cells because it increases healing actions above using fat or bone marrow alone.

As research advances, however, stem cell therapy will become more and more popular. Joint injections with stem cells to treat athlete horses will increase – with drug testing and certain medications banned, horse owners will want products that are natural and produce healing, not ones that just provide pain relief. Costs of certain stem cell therapies will come down to allow their use in pleasure and backyard horses. In time, this therapy won’t sound quite so futuristic anymore, nor will it be reserved mainly for high level performance horses. With a bit more time and research, it has the potential to become an excellent and affordable natural option for all horses.

Selecting a Stem Cell Product

You need to consult with your veterinarian on the best stem cell product for your particular horse’s injury. Recent studies show that ultrasound misses about 20% of the injury’s length, so a 2” tendon strain is more like 2.5”. The longer the injury, the more stem cell injections are needed, so a product making three to four injections will not work on a knee to ankle suspensory problem.

The cost of PRP is about $700 on average, and fat/bone marrow (including surgery, culture and injection) is about $2,500 to $3,000. Take note – many insurance companies will pay for these treatments, so keep them in the loop.

The action of PRP is known, but the action of fat or bone marrow stem cells is not fully understood. These products are a “soup” of stem cells, fat, growth factors, blood cells and connective tissue. One company said it best: “Cells injected into an area probably do not become the cell tissue it is injected into. They only stimulate resident cells.” They create an environment of healing but rarely, if ever, are they turning into tendon or cartilage.

Dr. Frank Reilly is the head doctor at Equine Medical and Surgical Associates in Wests Chester, PA with over 25 years as an equine veterinarian. A member of AAEP and also AAPF, he has worked on six world record racehorses and multiple track record holders and is a regular speaker at the International Hoof Summit, the largest farrier convention in the USA. His website on equine insulin resistance and equine summer eczema is top rated on the internet. equinemedsurg.com