Hello, my name is***** and I have over 20 years of experience as a veterinarian. I understand that Mugsy is struggling with two serious diseases (COPD & renal failure) and you are concerned because he seems to be panting excessively today.
How high were his kidney values?
Is he spilling excessive amount of protein in his urine?
Was his blood pressure elevated?
If he has been on prednisone long term and has not been panting previously then that is less likely to be behind his panting today.
Is he eating and drinking well? If so and his kidney values weren't very high then kidney failure is less likely to be causing his panting. Dogs with kidney failure can experience metabolic acidosis, and that will cause them to pant more. But dogs that have that severe degree of kidney failure have very high kidney enzyme levels and changes in their electrolyte patterns. If his values weren't that high then I don't think his increased panting is related to kidney failure.
It is possible that he is panting excessively because he is off Theo-Dur, and his COPD is not as well controlled as it was when he was taking it. Although we need to be cautious when prescribing Theo-Dur in dogs with kidney failure, as it can increase blood pressure and also acts as a mild diuretic both of which can further stress the kidneys, in some cases we can use a low dose when the positive effects from the medication outweigh the risks.
This is something that needs to be discussed with his veterinarian in light of whether his blood pressure was elevated and how high his kidney waste product levels were.
Please let me know if you have any further questions.