Leptospirosis is a zoonotic disease caused by pathogenic species of a spirochetal bacterium of the genus Leptospira. It is most commonly spread through direct contact with contaminated urine from reservoir hosts, such as rodents, skunks, raccoons and deer, or other objects that serve as fomites. Once an animal is infected, the bacteria spread systemically and most commonly cause an acute nephritis and/or hepatitis. If not treated promptly with appropriate antibiotic therapy and supportive treatment for the organs involved, this infection can be fatal. The most common diagnostic test used in veterinary medicine is the microscopic agglutination test (MAT). Diagnosis is based on obtaining a titer greater than or equal to 1:800 in a non-vaccinal serovar, or a 4 fold increase in paired titers performed 7-10 days apart. The following case report illustrates the presentation, diagnosis, disease progression and treatment of a classic case of canine leptospirosis.