My 13 year old terrier mix had bladder surgery four years ago to remove a massive bladder stone. She had suffered with bladder infections for years and ended up with blood in her urine and needed 2,000 dollar surgery! A very large stone was removed. After the surgery to avoid *another* expensive, painful surgery I started sprinkling cranberry powder or D-mannose with Cranactin powder on her food. Just a quarter to a half a powdered capsule. It worked GREAT! The urinary tract infections stopped and the crystals stopped appearing in her urine. Her vet said to keep doing what I was doing because it worked! I also give her bottled water now.