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.
[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.