This study aimed to analyze the case series of canine leptospirosis at the University Veterinary Hospital - UFPI. A total of 82 dogs were treated between 2018 and 2019, with suspected leptospirosis. For confirmation, the Microscopic Seroagglutination Test (MAT) was performed. The sera classified with 50%, 75% and 100% of agglutination were submitted to a second test of the MAT for titration with the reactive serovars, considered infective the one with the highest titer, with 35 (43%) reagents and 47 (57%) non-reactive. It is concluded that leptospirosis is widespread among dogs from Teresina - PI and has its main hosts in synanthropic rodents, as well as the dog itself.