Prevent Barren Cows this Year - Consider Leptospirosis.

Author: Jon Mouncey BVetMed DBR MRCVS, Director and Senior Vet at Westpoint Veterinary Group

Excellent reproductive efficiency is fundamental to the profitability of any livestock enterprise. Effective infectious disease control is one critical step to maximise the reproductive potential of beef and dairy herds. In suckler herds, if more than 5% of your cows are barren after a 9 week breeding season you need to know why. In this instance, a systematic approach can help; ask yourself 5 simple questions to work through with your vet.

Did the barren cows:

  1. Have difficulty with their previous calving?
  2. Calve late in the previous season?
  3. Go to the bull in poorer body condition?
  4. Run with a sub-fertile bull?
  5. Become exposed to an infectious disease that could affect their fertility?

Leptospirosis is a disease that most livestock owners have heard of over the years, and in fact recent infectious disease surveys have positively demonstrated over half of beef and dairy herds tested positive for Leptospirosis.

Leptospirosis in cattle is a disease caused by organisms referred to as Leptospira hardjo. Within the UK there are 2 strains widely spread, Leptospira hardjo prajitno and Leptospira hardjo bovis. Within dairy herds, the colloquial name for Leptospirosis is “Flabby Bag Syndrome” as clinical signs of the disease include sudden and profound milk drop of all 4 quarters within 2-7 days of encountering the organism. Affected animals may have a high temperature but after 5-6 days milk production resumes unless in late lactation when the cow may dry off altogether. Abortion storms can occur, within 2 months of initial infection 30-50% of the herd can be infected, with abortion occurring within 1 to3 months of encountering the organism. Abortion can occur at any stage of pregnancy, but has been found to be mostly in the last third of pregnancy with a marked seasonal incidence in late summer. If the cow is infected close to calving, inflammation can occur in the placenta resulting in a weak, infected calf and possibly retained foetal membranes.

The organism localises in the reproductive tract and kidneys of the cow and is shed in the urine. Transmission is either in utero, through infected milk in calves, through contact with infected urine, aborted tissues and fluids, infected water courses or by an infected bull during mating. The organism can be shed intermittently or continuously, and untreated animals can shed for life with the organism able to persist within the environment for up to 4 months.

L. hardjo can affect you never mind your herd. It can be transmitted to humans with similar sources of infection including urine, aborted fluids, and uterine discharges. Infection can result in a flu-like illness including fever, headaches and muscle pain. Herd owners must therefore be aware of their responsibilities under COSHH regulations.

Introduction of Leptospirosis to a herd is nearly always through the purchase or hire of infected cattle. However L.hardjo has also been isolated in the urine of sheep and studies have shown that where sheep have been grazed on farm, cattle herds are more likely to be infected with Leptospirosis.

To diagnose infection in your suckler herd you will need to work with your vet to blood sample a statistically significant number of animals. Dairy farmers can routinely monitor bulk milk or perform cohort milk samples to determine their disease status. All cattle that have aborted should be sampled to determine exposure to Leptospirosis. When testing it should be born in mind that the dam may have mounted her immune response before the foetus died and was aborted. This is important to take into account when determining which test might be most useful to perform. Currently tests do not determine whether animals were naturally infected or vaccinated. Most importantly, if you are going to investigate any infectious disease including Leptospirosis, know the limitations of the test being performed and be prepared for the result.

If small numbers of older individual cows that have freely mixed with the herd, are identified as antibody positive upon testing, consideration could be given to antibiotic therapy. However treatment cannot guarantee elimination of infection / carrier status and so regular monitoring should continue within the herd if vaccination is not to be implemented. Vaccination is an effective means of controlling infection of Leptospirosis within your herd and crucially is far from cost-prohibitive. A booster vaccination / full vaccine course should be administered prior to turnout and prior to breeding maiden heifers respectively. A full vaccination course requires 2 vaccinations administered 4-6 weeks apart and boosters should be administered within 12 months of completion of the primary course. Now is the time to either start investigating Leptospirosis in your herd, or considering vaccination before stock are turned out onto potentially infected natural water courses or grazing pasture infected by urine from diseased animals. This is a disease that you can take ownership of and control effectively within your herd.

For further information, or if you have concerns about Leptospirosis, please contact your vet.

25th February 2013

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