9yr old border collie mix started limping

:confused: My 9 yr old border collie started limping out of the blue moon. It seems it started about two weeks ago, sometimes she can not step on her foot for a couple seconds, than other days she is fine the last three days I took her for good long walks and now she almost seems worst, now I notice sometimes when she is lying down she takes her time. I used to call her and she would run to me, now she looks but it seems that she hurts when she has to move. She doesn't cry or make any noises of beeing in pain.
I figure its a strained muscle, how long should I wait?
I am scared to go to the vet and they might tell me bad news, like cancer or artheritis.
She is on two medications on is a tyroid medication the other one is a prednisone, but even beeing on the medication she is otherwise a healthy dog. Somebody told me this is very common problem for border collies.

Your dog needs to go to the vet. My 10 year old rottweiler started limping, I lost her within a month to cancer.

You need to get her to the vet. You may be afraid that the vet will diagnose cancer or some other ailment, but your dog is in pain. You owe it to her to try to find a way to stop that pain.

You must take your dog to the vet. I know that it is hard when you are worried that they may say something you don't want to hear. But how can you treat something with out having it diagnosed? It could be something that you can treat and be done with it.

It could be many things. It could be arthritis. This is manageable with glucosamine supplements. When the pain is really bad there are pain killers. Avoid the long walks until you get her looked at. If it arthritis, you are probably making it worse.

It is better to know what is causing her pain and get it treated now at the early stages than have it get worse and beyond the point of treatment.

Good luck and please keep us updated.