Traditionally, leptospiral abortions were thought of as late-term losses and the source of infection was a contaminated environment due to wildlife, dog, or swine reservoirs.  These late-term abortions are caused by several serovars including Leptospira interrogans serovar hardjo (type: hardjo-prajitno), Leptospira interrogans serovar pomona, Leptospira interrogans serovar canicola, Leptospira interrogans serovar icterohemorrhagiae, and Leptospira kirschneri serovar grippotyphosa.  The standard 5-way leptospiral vaccines provide protection from all of these pathogens; however, an additional leptospiral threat exists, Leptospira borgpetersenii serovar hardjo (type: hardjo-bovis).

  For hardjo-bovis, cattle are the maintenance host.  The reproductive tracts and kidneys are colonized and cattle serve as the source of infection in a herd.  The traditional late-term abortions can occur, but the real effect is overall reduced reproductive performance.  Herds see reduced conception and pregnancy rates, increased early embryonic losses, and stillbirths and weak calves.

  Eliminating carriers is key to minimizing losses associated with leptospirosis once a diagnosis has been established within a herd.  To diagnose a herd problem with hardjo-bovis, serum and urine samples are required from a representative sample of the herd.  Any open cows should be included in that sampling.  To facilitate flushing the leptospiral organisms from the kidneys, cows are given furosemide and the urine sample is collected from dilute urine that is voided after the initial concentrated urine is voided.  The urine is chilled in red-top tubes.  Although serology is typically more useful with the L. interrogans and L. kirschneri serovars, serum samples should also be collected from the same animals that provided the urine samples.  If aborted fetuses are available, useful samples include kidney, liver, lung, urine, and thoracic or abdominal fluids.  Contacting your diagnostic laboratory for guidance on what samples to submit and how to package them for shipment is always recommended.

  Once the diagnosis of hardjo-bovis is established, carriers are eliminated by treatment with oxytetracycline.  A diligent herd vaccination program that includes not only the traditional 5-way vaccines, but the new Spirovac vaccine for Leptospira borgpetersenii serovar hardjo (type: hardjo-bovis) is necessary.  Spirovac is safe and effective in calves as early as 4 weeks of age.  Initial vaccination includes 2 doses at 4-6 weeks apart.  Once the entire herd is initially vaccinated, annual vaccination is required to maintain protection.  Additionally, any additions to the herd should be isolated and follow the same treatment and vaccination schedule used to initially clear the herd.

-by Dr. Julie Davis, Class of 2005
-edited by Dr. Leon Thacker, ADDL Director

References:

1. ABS Global Technical Services: 2003. L. hardjo-bovis: Preventing the Silent Profitability Killer. Breeders Journal. June, pp 2-5.

2. Heath SE, R Johnson: 1994.  Leptospirosis. JAVMA 205: 1518-1523.

3. Schlafer DH: 2003.  Bovine Placental Pathology - an Overview of Placental Development, Infectious Disease, and Diag-nostic Features in Cases of Pregnancy Failure.  Proceedings Society for Theriogenology Annual Conference and Symposium 137-144.

4. Wikse SE: 2004.  At Last: An Effective Control Program for Leptospira hardjo-bovis. Veterinary Quarterly Review. 20:1-4.

5. Wikse SE: 2003.  Practitioner's Approach to Investigation of Abortions in Beef Cattle. Proceedings of the Society for Theriogenology Annual Conference and Symposium. 214-220