Zusammenfassung: Es wurden die Krankengeschichten von 15 Pferden und Eseln ausgewertet, welche in den Jahren 1996 -2011 wegen einem Harnblasenstein am Departement für Pferde der Vetsuisse-Fakultät der Universität Zürich behandelt wurden. Es handelte sich dabei um 14 Patienten (8 Warmblutwallache, 1 Ponywallach, 2 Warmblutstuten, 2 Eselwallache, 1 Eselstute), wobei ein Eselwallach zweimal operiert wurde. Die häufigsten klinischen Symptome waren Hämaturie (14), Strangurie (7), Pollakisurie (7) und Kolik (4). Bei der Harnuntersuchung konnte in den meisten Fällen Hämaturie (12/13) und Proteinurie (11/13) Schlüsselwörter: Urolithiasis / Harnblase / Hämaturie / Lithotripsie / Laparozystotomie Cystoliths in the horse -A retrospective study A search of the medical record data base of the Equine Hospital, Vetsuisse Faculty, University of Zurich, Switzerland yielded 15 cases with urinary bladder stones referred for treatment from 1996 to 2011. The median age of patients was 15 years (8 to 29 years), and there were 8 warmblood geldings, 1 pony gelding, 2 warmblood mares, 2 donkey geldings and 1 jenny. One donkey gelding was operated twice. The most common clinical signs were haematuria (n =14), stranguria (n =7), pollakiuria (n =7) and colic (n = 4). Mild haematological abnormalities were seen in some patients. The main serum biochemical abnormalities were mild hyperglycaemia (n = 5), hypoproteinaemia (n = 2) and increased creatinine concentration (n = 2) in addition to other mild abnormalities in some patients. Haematuria was seen in 12 of 13 samples and proteinuria in 11 of 13 cases. Bacteriological culture of the urine of five patients yielded Enterococcus spp. (1/5) and Staphylococcus spp. (1/5). Cystoscopy showed one or more bladder stones in all 15 patients and inflammation of the bladder mucosa in 13. Sonographic examination of the urinary tract in four horses revealed a bladder stone in three and an additional ureterolith in one. Treatment included laparocystotomy (6/15), laparoscopic cystotomy (1/15), lithotripsy (5/15), manual intraurethral removal (2/15) and bladder lavage with a urethral catheter (1/15). Laparocystotomy was carried out with the horse under general anaesthesia and in dorsal recumbency using a paramedian approach. An electrohydrolic lithotriptor was used for transurethral lithotripsy in standing sedated horses. Laparocystotomy allowed bladder stone removal in toto (5/6) or in multiple fragments (1/6), and laparoscopic cystotomy was also successful for urolith removal. Lithotripsy was conducted in one (2/5) or multiple sessions within 3 or 4 days (3/5), aided by bladder irrigation (4/5) to aid in fragment removal. The bladder stone was removed manually through the urethra in two mares and by means of bladder irrigation in a jenny. Complications of laparocystotomy included preputial and/or ventral abdominal oedema (6/6), abnormal micturition including stranguria and pollakiuria for two to three days (2/6), transient penile prolapse (1/6), myopathy (1/6), fetlock injury during the recovery phase (...