What JB said. Rapid early growth is linked to DOD/OCD. You want to make sure the foal is getting all the amino acid, cal/phos, copper/zinc and protein building blocks it needs to complete ossification in all joints.
I would (and have... on fast-growing foals) be giving a shot of adequan once a month, starting at 4 months for six months. There is no science to back up the Adequan, just conversations with some folks on the big TB farms and their anecdotal stories of OCD reduction when yearling sales surveys are done.
"No matter how cynical I get its just not enough to keep up." Lily Tomlin
Best way I know to support rapid growth is to supplement with Rejuvenaide or Rejuvenaide Plus (by Progressive Nutrition) or Foal Aid (by Buckeye). Progressive Nutrition's nutritionist, Don Kapper, has a long standing special interest in this particular problem, breeds WB's himself, and he and his company are very good about answering questions, even to the point of analyzing your horses' present situations/diets/general management, and designing rations to meet their individual needs. If you call Progressive Nutrition's 800 number, I'm sure they will be glad to help.
How long should I plan to give it since she is not having any problems and I am using it as a preventative. I also plan to ask my vet about the once monthly Adequan once she is 4 months old but they don't have a ton of experience with
WB babies due to the area I live in.