A 3‐year‐old, female, entire guinea pig presented with an 8‐week history of dysuria and vocalising when urinating. Investigations included radiography, ultrasonograpy and urine culture, which did not yield a definitive diagnosis. Medical management continued over a 3‐month period during which time, the clinical signs waxed and waned. A computed tomography scan was performed, which revealed cystitis, cystolithiasis and evidence of a persistent urachal remnant. Surgical resection of the urachal remnant was performed. The guinea pig made a good recovery from the procedure, and clinical signs have not returned 9 months later.