L. canicola. Dogs are the reservoir host (organism is host-adapted in dogs), and thus sub-clinical infection is more common than acute disease in dogs. Urine shedding of L. canicola is usually seen in large numbers and for long periods, so this can spread infection to other dogs. Subsequent to infection, antibody titers increase (to ˜ 1:1,600) but then decline. Chronically, titers decline and dogs may become seronegatiove shedders of organisms.

L. icterohemorrhagiae. Rats are the reservoir host, but infections in dogs are seen associated with farms or urban environments where rats are present. Dogs may shed organisms in urine for a few months.

L. grippotyphosa. Wildlife (raccoons, possums, deer) are the reservoir hosts, but dogs shed organisms in urine only for short periods Titers tend to stay high after infection (˜ 1:3,200 - 1:6,400), often for a year or more.

L. pomona. Reservoir hosts include pigs, cattle, skunks, possums; dogs shed organisms for short periods only.

L. bratislava. Pigs are reservoir hosts, and source of infection for dogs is uncertain. Dogs shed organisms in urine for only short periods.

L. hardjo. Cattle are the reservoir hosts.

L. autumnalis. Mice are the reservoir hosts, but the importance of this serovar as a cause of clinical illness in dogs is uncertain.

Microscopic agglutination test
(see above for titer interpretation)

Mix dilutions of patient and control sera with live organisms, and look for agglutination microscopically. The endpoint titer is the highest dilution that causes 50% agglutination of live organisms. Accuracy is +/- one dilution.

Urine testing for organisms (RCR, Fluorescent Antibody)

Limitations with this methodology—organisms need to get into the renal tubules in significant numbers before they will be shed into the urine. Organisms are not usually found in urine until 5-7d after the onset of illness. Once treatment has commenced, organisms will no longer be detected in urine (most dogs have already been treated by the time they are referred). FA testing is done primarily in cattle looking for L.hardjo.

Animals ill from leptospirosis should be treated with penicillin or ampicillin, although cephalosporins are also effective. The organisms are killed quickly by §-lactam antibiotics. Once dogs start to feel better (or if they were never ill), one can switch to doxycycline. If doxycycline is not tolerated, use a fluoroquinolone or amoxicillin. Corticosteroids may help with per-acute cases, but antibiotics should be used beforehand or concomitantly.

[Contributed by Dr. Carole Bolin, Michigan State University.]

Antech offers to test for all serovars listed above:
Test code S16514
TAT 5-10 days
Sample: Urine sediment resuspended in 1-2 mls of normal saline (pooled sediment from 2 or 3 urine samples is best as organism may be shed intermittently).