I have a nearly 4 year old English Lab. He has been limping off and on for about 6 months and is now limping weekly. The limping switches between legs on any given day and will disappear for a week or more at a time like nothing every happened. I took him to the vet this morning and they are testing for valley fever and ran x-rays. The vet is not completely sure what is it is that is causing his random 24hr limping. The vet says possibly Panosteitis (Bone Inflammation) or Polyarthritis. I am very concerned that even the vet is not fully sure what is going on. He was put on anti-inflammatory meds and pain meds (which I hate giving to him). I am hoping that a dog parent out there might know something that none of us are picking up on. (My dog was on fish oil for the last 6 months and I took him off and the limping still remained).