Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
I am so sorry to hear about Spud's condition....I know this is scary!
Your vet needs to do testing if this has not been done.The possibilities for this decrease in red blood cells is the following:
Kidney or liver disease
Bleeding splenic tumor
Autoimmune Hemolytic anemia
Make sure your vet runs Xrays and Ultrasounds to rule out a tumor that can be removed. Have them run an autoimmune profile blood test along with a complete blood panel including chemistries to rule out an autoimmune disease and/or kidney or liver disease. If this is an autoimmune hemolytic disease , this will require other medications such as Cyclosporine as an immune suppression medication.
Spud is getting to a dangerous point that he may require a blood transfusion but it is extremely important that the diagnostics be run on sweet Spud so the correct treatment can be given. Many of these possibilities on the differential list do have treatments that can be curative or at least stop this process and ease his discomfort.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
Sincerely, ***** *****