Lepto is a dreaded abortion disease of cattle. In the last few years we have figured more out about this problem. We have found Lepto to be in almost every mammal, including man. I have known a local dairyman that came down with it. He almost died in the hospital from it. Therefore, this is truly a zoonotic disease and can be transmitted to man.
The bacterium that causes this disease is Leptosporia sp. We have many different species of these bacteria. The one that cattle can carry is Lepto hardjo. Before we did not know that we had a species of Lepto that cattle carried. We now know that this species of Lepto is carried by cattle and is transmitted. The classic way Lepto is transmitted is by an animal urinating and then an animal drinking the water. I have always wanted a picture of a cow urinating in a creek and another cow taking a drink from the same creek. This would be the ideal picture showing the transmition of Lepto.
A few years ago a major research project was done across the nation checking for the infection rate of Lepto. Samples were checked from cattle in every state in the United States. These samples revealed active Lepto infections in every state. But, what was alarming was the 42 percent infection rate. This means that at least 42 percent of our cattle were infected with Lepto.
But, we have had Lepto vaccines for years and we all give them to our cattle, right? Well this research project proved that they we not working as well as we thought. We now have Lepto vaccines with this new form of Lepto Hardjo. We even have a vaccine now that has been proven to clear cattle of these spirochetes, (Lepto). This new vaccine will only clear Lepto if given twice, 2-4 weeks apart.
The main antibiotic we used to use was Streptomycin. Supposedly one dose at the rate of 25 mg/lb of body weight would clear a cow of Lepto. Well this antibiotic has been removed from the shelf due to antibiotic residues. It was part of the combination known as Combiotic. Now all we have is the tetracycline’s to work on Lepto. This would be the LA 200 group of antibiotics. And we may have to treat them for at least a week to have it work.
Clinical signs of Lepto in a herd of cattle are late term abortion and unthrifty calves. Yes calves can get Lepto. Recent research has shown that we should vaccinate our calves for Lepto. The stockers and feed lots have had a lot of trouble with calves not getting over respiratory disease and not having the immune system they should and then Lepto was diagnosed on post-mortem examination in these calves.
Dr. Tim O’Neill owns Country Veterinary Clinic in Farmington, Ark.


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