had an issue with my past lab many yrs ago, kinda same thing but she got very weak and ill, turned out had infection in her blood causing her red blood cells to die and she would pass the dead cells thru her urine not a deep red blood , the infection was caused when she cut her "wrist " on front leg very deep severed veins ....the infection didnt show up for many months after, long story short she need a blood transfusion and medication several months to heal up....