[PawNHoofPrints]

Does anyone know what blood lines combined immunodeficiency is found in in Arabians or a website, etc. that would give the information?

I can find info that 25% of Arabs in the US are carriers and each year 2-3% of foals are born with it. As well as the disease is found in the US, Great Britian, and Australia, and is believed to have begun as a genetic mutation in a horse in Great Britian and then spread through importation of horses from there to other countries.

Thanks.

[Sandra-A1]

I doubt you will find many Purebred stallions that are SCID positive advertised as such.
There are a few (but a very few) stallion owners who have come forward for example:

December 1997 - Gene and Sue Mathews, West Hills, California:
It is mid-fall now, three months after the Canadian Nationals where our stallion Eqynox was named the unanimous Champion Stallion, and we have just had confirmed the fact that he and his sire Myrlyn have tested out to be carriers of the autosomal recessive trait known as SCID.

There are stallions that have been tested and are CLEAR and are advertised as such. While there are rumors and gossip about which Stallions are SCID Positive (some not at all true) the best you can do is to learn all you can about SCID and make your own decisions when it comes to breeding.
The more active you are in the Arabian Industry the more information you will aquire as to who has recently lost foals to SCID and what horses were involved.
As long as a positive mare is not bred to a positive stallion there is no problem. Since some Arabian owners do not test their stallions or mares it is, in my opinion, a wise decision to have your own mares (and stallion if you own one) tested so you will at least know if any of your breeding stock is positive and you can then make wise breeding decisions based on that horse's test results.

SCID In Arabian Horses