Calcification of the urinary bladder in the wild cotton rat (Sigmodon hispidus).

Calcification of the urinary bladder epithelium was observed in 19 of 30 and 18 of 30 wild cotton rats from control and petrochemical-contaminated sites, respectively. The rats in the two sites did not differ significantly in respect of serum calcium and phosphorus concentrations. The calcification was considered to be dystrophic in nature. An unidentified factor common to both control and petrochemical-contaminated sites was considered to be responsible for this syndrome.