Two horses were injured when the trailer they were riding in overturned on the ramp from Route 1A to Interstate 495 North in Wrentham late Tuesday morning, State Police said. The horse trailer, being pulled by a pickup driven by a 55-year-old West Tisbury man, tipped over around 11:30 a.m. near Exit 15, said David Procopio, a State Police spokesman. Neither the driver nor his 51-year-old female passenger were injured, Procopio said. A Wrentham animal control officer, Christopher Wider, said the horses were taken in another trailer to Tufts New England Veterinary Medical Center in Grafton. They were able to stand on their own, but Wider said that both were a “bit lame.” Procopio said the incident is still under investigation to see if speed was a factor. If so, charges may be pursued.