The objective of this paper was to present a case of urolithiasis in a two-year old Pug weighing ten kilos, with a history of food allergy/atopic dermatitis. Upon physical examination, the animal presented mild abdominal pain upon palpation. The tutor indicated emesis 2 days ago. Upon ultrasound examination, it was possible to identify the presence of a 2.2 cm urolith in the bladder, in addition to cystitis in the urinary tract. The animal underwent surgical treatment, with cystotomy being the most suitable for this type of case. From the case report, it was found that racial or even familial predisposition was the main cause of urolith formation. In addition, the chances of urolithiasis occurring are greater in small breed dogs.