[QUOTE=Kyzteke;8032283]
I totally understand what “carrier” means.
My point was that, at worst, all my horses (and the horses behind them) could be is carriers.
What I meant was that, given all the evidence & history of all the horses involved, the risk was seriously minimal.[/QUOTE]
You may understand the meaning of carrier, but the phrasing of your earlier statement could be confusing to people who don’t.
There is a TON of misinformation about these disorders and how to manage the risks; it is important to have clarity in these discussions because there are people reading who may utilize the information they read here in other contexts.
FWIW, neither SCID affected nor LFS affected foals ever live to breeding age. SCID foals typically die at a few months of age after their maternal antibodies wane and they succumb to some kind of infection since they have no ability to mount an immune response. LFS foals die within hours or a few miserable days unless euthanized sooner. So there are no SCID or LFS affected horses of breeding age–only carriers and clears.
CA affected horses are typically euthanized prior to breeding age due to their neurological symptoms, but some horses have had such mild signs that they can be managed. Prior to the CA test and the spreading of awareness of the existence of CA, some mildly affected horses were used for breeding. A handful of well documented cases have revealed CA affected (homozygous) horses with NO overt neurological signs. There was one stallion who was a successful endurance horse. Research is ongoing to try to unravel why CA affected horses show such different levels of expression.
So in the case of SCID and LFS, every ADULT Arabian horse’s worse case scenario is that it is a carrier because affected foals NEVER survive; your horses are not any different in that regard. For CA that is also largely true with the very rare cases of asymptomatic and slightly less rare mildly symptomatic CA affected horses.
In your case, the risk of producing a foal afected by any of these disorders IS minimal. Personally, I prefer to be 100% sure I won’t produce any foals that are affected. Having at least one tested clear horse in the mating pair assures that. I also believe there is value in knowing whether or not any carriers are being produced in order to work most effectively toward decreasing the frequency of these alleles as well as to avoid introducing them into breeding populations where they either don’t exist or exist at extremely low frequencies. YMMV.
