How long does it take for a should sprain to heal in a dog? My German Shorthaired pointer also has a shoulder sprain, and it  can take 2 - 4 weeks for it to heal. I recommend to help them  rehabilitate it gentle massage on the sprain … , frozen peas to chill  it, and gentle movement. Do this after the first week.ow long it can take for a sprained knee to heel is dependent upon  the severity of the injury and the patients capacity to heal. It  could take anywhere from a few weeks to … a couple of months for  healing to occur. 1 person found this useful.