Canine Leptospirosis

Canine Leptospirosis is more common than previously realized. In dogs the infection results in varying severity and presentations depending on the infecting serovars, geographical location,and host immune response. Some dogs display mild or no signs of disease, whereas others develop severe illness or death. In Kansas veterinarians should suspect leptospirosis in dogs with signs of renal or hepatic failure,pulmonary hemorrhage, acute febrile illness, or an abortion.

The two tests routinely utilized for the diagnosis of canine leptospirosis are serology by the traditional microscopic agglutination test (MAT), and polymerase chain reaction (PCR)testing (blood or urine). Used in combination, this antigen and antibody test offer the best combination to maximize accuracy.

Using MAT, the optimum confirmation of a diagnosis of leptospirosis is to document a 4-fold rise or higher in the reciprocal titer over a 2-4 week period (e.g., 800 initially and then 3200 two week later).The PCR identifies the presence of the leptospiral organism in urineor blood and is unaffected by previous vaccinations. Note: the PCR test may be negative if the patient is not bacteremic, not shedding organisms in the urine or is on antimicrobials.

Given that false negative test results may occur with either the MAT or PCR, per forming both tests on a patient in which leptospirosis is suspected is recommended and
the combination provides the greatest diagnostic accuracy.