Urolithiasis in 20 guinea pigs (Cavia porcellus)

During 1989 to 1996 20 cases of urolithiasis in guinea pigs were diagnosed. 15 (75%) of the animals were female, the mean age of guinea pigs with urolithiasis was 4.6 years. In five males and two females cystic calculi were diagnosed, in 13 female guinea pigs calculi were located in the urethra near the ostium urethrae externum. Three urethral calculi were removed by forceps, one by palpation manipulation, the rest surgically by cystotomy or urethrotomy. According to the results of infrared spectroscopy, calculi consisted of two or more minerals. Except of two all stones contained calcium carbonate, 12 calcium phosphate and three calcium oxalate. In 10 cases the calculi contained masses of struvite. Urethral calculi should be considered in the differential diagnosis of female guinea pigs in cases of hematuria and in cases of unremarkable clinical examination.