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Lepto hardjo-bovis: Too costly to ignore

Doug Scholz Published on 03 February 2010

Surely you’re familiar with the old saying “an ounce of prevention is worth a pound of cure.”

This cliché actually offers valuable advice when it comes to stopping Lepto hardjo-bovis from robbing your dairy herd’s profitability.

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Lepto hardjo-bovis is the most common cause of bovine leptospirosis in the U.S. And a recent Michigan State University study confirmed L. hardjo-bovis is more prevalent than previously thought. The study tested urine and fluids from 15 cows in 44 dairy herds from four different regions of the U.S. Results found at least one infected cow in 59 percent of the herds tested.

Once a cow is infected with L. hardjo-bovis, the disease settles in the kidneys and reproductive tract, where it often causes major reproductive problems, including conception failure and early embryonic death. Infected cattle can continue shedding the pathogen for years through urine and other bodily fluids. Unfortunately, many cattle infected with L. hardjo-bovis won’t have outwardly visible symptoms or signs, so reproductive problems associated with a host animal may be falsely blamed on breeding protocol problems or human error.

Making matters worse, when L. hardjo-bovis infects one cow, it affects an entire herd. Because of the organism’s presence in urine, all animals are considered exposed. In infected herds, it is common to have 30 to 40 percent of infected cattle with urinary shedding at any one time.

Lepto hardjo-bovis can be transmitted during breeding, as well as from cow to fetus. Abortions occur in the last three months of pregnancy, but are sporadic rather than coming in storms. This subtle but damaging disease results in fetal losses after conceptions due to persistent infections of the reproductive tract.

How L. hardjo-bovis steals profits

The economic losses associated with L. hardjo-bovis come from many areas. Although they often go unrecognized or attributed to other factors, these expenses can have a significant impact on your operation’s profitability:

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  • Extra days open – Cost estimates range from $1 to $5 per day open, according to dairy reproductive specialists, with most experts settling around $3. Miss the heat cycle, and you’ve extended the calving interval by 21 days. Multiply 21 days by $3 per day and that equates to $63 for just one dairy cow.
  • Infertility, embryonic death and rebreeding – L. hardjo-bovis is also associated with reduced conception rates. In a study that looked at fertility data from 673 cows in five dairy herds, the overall pregnancy rate of seronegative cows was 28 percent higher than that of cows with a MAT greater than 1:100 for L. hardjo-bovis. An early pregnancy loss that causes an increase of 45 days open can result in a loss of between $90 and $225.
  • Reduced milk production – Cows that have poor conception rates may not produce enough milk in late lactation to remain profitable. A Canadian study found a mean reduction in net revenue of approximately $4 per cow from a one-day increase in the adjusted calving interval.
  • Culled cow expenses – Selling open cows means incurring the cost of raising or purchasing replacement animals.

Diagnosis, management and prevention

Diagnosing L. hardjo-bovis can be difficult. Since L. hardjo-bovis is host-adapted, searching for titers in a blood sample is not a foolproof method for determining if a herd is infected. Currently, L. hardjo-bovis is diagnosed using a combination of serology and identifying leptospires in the urine using fluorescent antibody testing.

Controlling this pathogen requires a combination of biosecurity, antibiotics, vaccination and culling. Start by eliminating carriers through antibiotic treatment, combined with a vaccination program to prevent new infections. When selecting a lepto vaccine, make sure that it contains an L. hardjo-bovis serovar.

It’s important to work closely with your veterinarian, because in most cases it will be more cost-effective to treat and/or vaccinate for the disease instead of testing. Testing can cost as much as $50 per cow, whereas vaccines that contain the specific hardjo-bovis antigens average $2 to $3 per head.

Start a vaccination program when calves are as young as 4 weeks old to reduce the risk of those animals becoming carriers. If you cannot vaccinate the entire herd, start with replacement heifers, which generally are more severely affected by reproductive diseases. Replacement heifers should come from only well-vaccinated, well-managed herds, and be tested before they’re introduced into the herd.

Vaccinating your herd for lepto is a very affordable “ounce of prevention,” especially since it helps boost conception rates and can prevent substantial economic losses. PD

References omitted due to space but are available upon request by e-mailing .

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How to prevent Lepto losses

  • If you treat one, treat them all. Even if only one cow is positive for L. hardjo-bovis, administer a hardjo-bovis vaccine to your entire herd, including calves as young as 4 weeks old.
  • Remember reinfection. Antibiotics alone can still leave cattle susceptible to L. hardjo-bovis reinfection. An antibiotic regimen coupled with an effective vaccination program is the best way to prevent cattle from becoming reinfected.
  • Consult your vet. Your veterinarian is your best resource for helping you manage existing L. hardjo-bovis cases or developing an effective prevention strategy.

Doug Scholz is a Director of Veterinary Services with Novartis Animal Health. Email Doug Scholz.

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