Why does your old dog have a strong urine smell?

two other diseases cause bad breath. Most likely, you and your veterinarian would see other signs of either of these diseases. DKA, or severe Diabetes, causes a change in breath due to a change in metabolism. The other disease that can cause foul breath is kidney failure, which leads to a buildup of uremic toxins in the bloodstream. Both of these can be ruled out with routine blood screening tests.