I have a 13 year old cocker spaniel, Lily. Recently she has become less active, having trouble climbing stairs. My vet did bloodwork and said everything was normal except her RBC count was low, may have internal bleeding. Is there anything I can give her to help raise the RBC levels
A low red blood cell (RBC) count (AKA anemia) in dogs can have many reasons and the severity can range from an incidental finding to something potentially life-threatening. However, the first step is to find the underlying cause. First of all, I would look into how the RBC count was performed. If it was done by a machine there can be errors and an additional test such as a PCV (packed cell volume) that can confirm the anemia. Another method would be to have the test ran again to verify it is in fact true anemia.
Once anemia is caused, then there are several potential causes. For more information on specific causes of anemia, I recommend this article: https://vcahospitals.com/know-your-pet/anemia-in-dogs
It is important to also look at the severity of the anemia as well as other clinical signs. Your dog not getting up and down stairs and being less active could be a sign of an underlying cause directly related to the anemia, or potentially another issue completely unrelated such as arthritis, which is common in older dogs. A vet should be able to confirm whether or not there are signs of arthritis present with a physical exam.
As far as medications for anemia, it depends on what the underlying cause is and should talk to your veterinarian on what the most likely cause is given some of the information I described above.