Dogs can develop health problems that make them unable to urinate. Bladder stones are the most common cause. Some breeds, such as Schnauzers, Yorkshire Terriers, Bichon Frises and Pomeranians, are more prone to this. Underlying illnesses like Cushing’s disease and portosystemic shunts also increase the risk for stones, as does the presence of a urinary tract infection. Males seem to be at higher risk than females.