You waited 4 weeks to go to the vet? I would take him/her after a couple days and probably call them at least after 1 day.
A torn ACL is painful. Try walking around on a torn ACl for 4 weeks and you'll understand why you should go to the vet sooner.
Sep 05, 2008 Rating
ACL Tear by: Anonymous
Two years ago my Jack Russell was running in the back yard and I heard a yipe. We waited for about 4 weeks to see if it would heal and she continued to limp. We took her to the vet and they took xrays. We found out the ACL tore and would require surgury. 2500.00 later she is running around again. Hopefully this is not the case for you and your dog! Good luck!!