SPONTANEOUS URINARY CALCULUS IN YOUNG LEW RATS CAUSED BY CORYNEBACTERIUM-RENALE

Spontaneous urinary calculus was observed in only 27% of female LEW ra ts among nine inbred strains maintained in the Institute for Animal Ex perimentation. The condition occurred between 3 and 9 weeks of age wit h loss of weight, enlargement of the os urethral externum, anuria and general marasmus. All of the affected rats died from anuria 3 to 4 day s after the onset. The affected rats had one to ten infected stones or many fine crystals of sand, which consisted of magnesium ammonium pho sphate, in the urinary bladder and/or urethra. Analysis of microorgani sms revealed that Corynebacterium renale, known as a causative agent o f bovine pyelonephritis, was the most probable candidate for producing infection stones. This is the first report that the rat is spontaneou sly infected with C. renale. This could be a useful animal model for h uman urinary calculus and also for C. renale infection in the field of veterinary science.