Hopefully, you have dodged the bullet on the founder issue.
According to another article in the 'The Horse',
The Timeline of Laminitis where they induced laminitis in 5 horses and studied the changes in the horses, you should be getting into the timeframe when the symptoms will start to show up. Apparently the histological (microscopic, cellular level) changes are becoming visible at 12 hours with the onset of discernable 'clinical' signs following that.
Link:
http://www.thehorse.com/ViewArticle.aspx?ID=10856
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Clinical signs
Mildly increased digital pulses were first detected at 13 to 29 hours and became more pronounced from this time on, he reported. The typical constant weight shifting of laminitis was seen in all horses starting 20 to 43 hours after induction.
"Lameness in four of the five horses progressively worsened with signs of severe laminitis evident in all four feet," he noted. "The remaining horse exhibited a mild lameness in all four feet that remained constant once detected. All horses developed moderate to marked transient (6- to 8-hour duration) epiphora (watery eyes), blepharospasm (eyelid twitching), and corneal opacity, which was clinically diagnosed as corneal edema, between 30 and 40 hours." He theorized that the corneal BM was affected similar to the laminar BM, but corneal biopsies could not be taken to confirm this theory. The eye problems had all resolved by 48 hours, he reported.
Take-Home Message
"Laminar histological lesions are present as early as 12 hours (after the causative factor has been administered), before the onset of clinical signs of laminitis occur at around 24 hours," van Eps stated. "Basement membrane disintegration and detachments are early pathological events. Failure of the BM results initially in the stretching of dermal-epidermal attachments, leading ultimately to a complete failure of this attachment under load. Efficacious therapy should commence before 12 hours; we need to treat these horses very early if we want to prevent damage."