[header] How to detect canine bladder stones [title] Watch out for blood-stained urine. [step] Bladder stones rubbing against the delicate mucous membrane lining the bladder may cause it to become inflamed. When the bladder lining becomes inflamed it is prone to bleeding. 
This blood collects in the bladder and is passed out when the dog urinates. [substeps] Stones that are smaller than the diameter of the urethra should pass out with no problems.