lindapalm, I am no expert on irises so I leave them alone apart from giving them lime in winter, stripping back any leaves that have dried off, then giving them a good feed at the start of Spring. Here are a couple that flowered today. The yellow one is Lemon Twist, I can't name the other at the moment.Last photo is an Echium.
I really don't know what causes that problem with shelties but I think it could be an inherited problem, at least with Silk's family. She and her mother were effected, and I was told of others carrying a prefix that shows in their pedigrees. I haven't heard of it in other breeds, but that's not to say it doesn't happen. I might quiz a friend about it, see if she knows more.