Leptospirosis Vaccine Information

Aug 30, 2016

Leptospirosis Vaccine Information

As of November 2015, a vaccination for leptospirosis was approved for use in horses. It
is called Lepto EQ Innovator and is made by Zoetis. It is a killed, whole cell bacterin.
The product is labeled for vaccination of healthy horses 6 months of age or older as an
aid in the prevention of leptospirosis caused by Leptospira interrogans serovar pomona.
Vaccinated horses when challenged with the organism did not show leptospiremia (the
organism in the blood) or leptospiuria (the organism in the urine) as compared to
controls. The duration of immunity of this product has not been determined nor the
ability to prevent abortion.

The vaccine has demonstrated safety in foals as young as 3 months of age and
demonstrated safety in pregnant mares during the 2nd trimester. Additional safety studies
in pregnant mares are ongoing, remembering that it has only been available since last fall.
Equine leptospirosis is typically a sporadic disease. In central Kentucky, we primarily see
leptospiral-associated late-term abortions. Other clinical presentations include recurrent
uveitis and acute renal failure. Infection is acquired through exposure to the organism via
the mucous membranes or breaks in the skin. The leptospiral organisms are shed in the
urine of infected horses as well as the placenta, fetal fluids and urine of the mare in
abortion cases. Also, a number of wildlife hosts can shed Leptospira spp. in their urine.
Seroprevalence data from healthy horses indicate that it is common for horses to carry
titers to multiple serovars. Multiple serovar titers can result from direct exposure to these
serovars, cross-reactivity of the MAT (microscopic agglutination test) between different
serovars or both. In diseased horses, Leptospira interrogans serovar pomona is the most
commonly incriminated pathogen/serovar in the U.S.

Vaccination Schedule:

Horses 6 months of age or older: Initial two dose series, 3 to 4 weeks apart. Annual
revaccination is currently recommended.
Pregnant mares: The product has demonstrated safety in pregnant mares during the 2nd
trimester. Additional safety studies in pregnant mares are ongoing.

This information is being sent to keep you up to date of new vaccines and products
coming out on the market and help you and your client make informed decisions. We are
using this vaccination at a limited number of farms.