Horton was limited at Sunday's practice due to a hamstring injury, John Boyle of the Seahawks' official site reports.
Coach Mike Macdonald relayed Aug. 18 that Horton was dealing with a health concern but wouldn't elaborate further. On Aug. 27, Corbin K. Smith of SI.com reported that Horton's issue was of the long-term variety, but it wasn't until the Seahawks posted their first Week 1 practice report that its nature was revealed. Horton will have two more days to prove his health ahead of Wednesday's regular-season opener versus the Patriots.