My Dog Chihuahua Age 6 Years Old. He Went To

my dog Chihuahua age 6 years old. He went to vet hospital on Friday for surgery to remove bladder stones but doctor said she could not remove the stone so my dog stay at the hospital without any charge. I went to see my little dog to comfort him and I took him outside and he lift his leg for long time and I watch to see if he peeing and he was not peeing at all so I bring him back and told a lady there that my dog can't pee. so he stay there all weekend and I found out that doctor is going to surgery him tomorrow morning. pls tell me is stone can be remove easy?