Science is an incredible field of discovery and they are always discovering new things. I wasn't a breeder much before the advent of genetic testing for equines, but it is definitely more prevalent now than it was 10 years ago even. Even in this day and age, new genetic tests are constantly being added. Last year it was 5 panel, and this year they are adding a sixth. There are also extra tests for variants of diseases that aren't regularly tested.
Every breed has its own predispositions towards diseases, but my limited knowledge and research is only connected to the stock horse breeds. With that said, what tests are part of the 5 panel? The first and most commonly known is HYPP, Hyperkalemic Periodic Paralysis Disease. It has been talked about for years. It is a muscular disease caused by a genetic mutation traced back to the AQHA stallion, Impressive. Horses that are symptomatic have muscle tremors/spasms that can cause weakness or collapse.
A second disease on the panel is HERDA or hereditary equine regional dermal asthenia. It is a disease of the connective tissue. Horses with HERDA have skin that is loose in nature, tears, scars and has lesions across the back. Horse with HERDA are often euthanized because it can be painful and they cannot be used for riding, driving or breeding.
A third disease is PSSM or polysaccharide storage myopathy. The technical definition says that it is a glycogen storage disease that causes exertional rhambdomylosis. Got that? Yeah, me neither. When we had a horse come back as having PSSM through genetic testing I did a ton of research. The best I can understand it, when a PSSM horse is having an "episode" they "tie up". Old ranchers often would talk about "typing up" as a horse that has muscle stiffness, sweating and refusal to move after exercise. The word on the street is that PSSM horses are generally more reactive than non PSSM horses and might be the horses we wrote off in the past as "nutty" or "spooky".
A fourth disease tested on the panel is one I don't know as well, GBED or glycogen branching enzyme deficiency. This disease is characterized by muscle weakness, still births or late term abortions. If the foal is born, it will die as the heart, brain and skeletal muscles cannot function. From my limited research, I'm super thankful I don't have much experience with this one.
The fifth and final disease on the 5 panel is MH or malignant hyperthermia. I have really never heard of this disease or know of anyone that has experience with it. I had to do a bit of research and the website from the Animal Genetics website states the following:
"Malignant Hyperthermia or MH is a genetic muscle disorder that affects Quarter Horses and related breeds. Horses with the MH mutation may not show any physical signs of the disorder until triggered by exposure to anesthesia or extreme exercise or stress. Symptoms can include high temperature, increased heart rate, high blood pressure, sweating, acidosis, and muscle rigidity. Symptoms develop rapidly, and if not treated quickly, this condition can be fatal."
With the advent of genetic testing, many of the diseases should become less common as responsible breeders work to breed only negative horses and ponies. However, there is some debate to this as well. With a breed as small as POA, what will happen to our breed as more ponies are tested and found to be positive? Many of these ponies will be asymptomatic and could be for the rest of their lives. If we narrow our gene pool down and down and down, what will we have moving forward? Especially since new diseases are being discovered and researched and tested all the time.
As many of my friends will tell you, I'm not afraid to share my opinions. But this is honestly one hot topic issue that I'm still figuring out what my opinion is. If every positive horse/pony were never bred, I'm pretty sure we would be in trouble for quality horses/ponies being available down the road. There are so many aspects to quality breeding; conformation, disposition, movement, and yes - genetic testing is definitely a component of that big picture as well. A component, but should it be the end all/be all decision maker or breaker? That is a big ethical question I haven't figured out my answer to yet.
The other side to genetic testing is COLOR testing. That part is a whole lot more fun and exciting to talk about. There are tests for every aspect of color from dun, to the dilution gene which makes your buckskins, palominos, cremellos, etc..., to the test for red based and agouti (black markings), paint patterns like splash and our personal favorite - the LP and pattern tests.
LP, short for leopard complex spotting, is the test that POA and Appaloosas use to determine if their horse/pony is considered "colored" per breed standard. As stated in our FAQ page, that means it has mottled skin, visible spotting or roaning (not related to QH roan), sclera and/or striped hooves. Many POA and Appaloosas are born solid but color out with time. However, some are solid. This testing allows breeders to guarantee the foals will color by breeding ponies with the genetic traits to produce color to each other. Ponies that carry two copies of the LP gene or are what's called LP/LP and will always produce Appaloosa coloring when bred; even to a solid. Ponies that are LP/lp carry and show Appaloosa coloring but only have a chance of producing color depending on who they are bred to. Ponies with lp/lp are solid and would have to be bred to a pony with at least one large L to produce a colored foal and the chances are not great.
The PATN1 gene is the gene that allows for large amounts of white in the coat pattern. This would be your fewspot or leopard ponies. Invy is our first and only pony on the place to carry the PATN1 gene. As a family we have had a lot of ponies and have had only a couple of leopards in that time. We are super excited about the possibility of leopard foals in the future. They are so loud and fun! I stole the bottom image from Google, if it is yours, please let me know and I would love to give you credit.
Through color testing we discovered that Pepper is not black as she looked as a newborn, but red based (chestnut). We learned that China is indeed a bay, but does carry the gene that allows her to have dun markings (hence why her papers say dun). We know that Cher is indeed black and the others are all red as we expected. We know that Charlie, Invy and Pepper are homozygous and 100% color producers and China is as solid as they get. But we love her anyway.
Oh science, how we love you. There is so much we have learned and so much we have yet to learn. But the ride will be a fun one as we go. Maybe someday we will look back and laugh at how little we know, but for now... I'm feeling kind of smart today.
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