Animal Health remains a priority on farm – Leptospirosis focus

We are currently in the middle of unprecedented times with regard to human health. We must all adhere to guidelines from the HSE with regard to personal hygiene and social distancing to slow the spread of COVID-19. Despite the global pandemic facing humans, animal health remains a priority for farmers.

Grazing systems have been largely disrupted by the weather this spring. Calving is drawing to a close and turnout to grass is beginning to happen in parts of the country where ground conditions allow. As calving comes to an end, focus turns to breeding management. Selecting the correct genetics is vital to the performance of the herd and in order to fully achieve the genetic potential of the herd, correct decisions with regard management, nutrition and animal health must occur. For the purpose of this article, we will focus on Leptospirosis, a disease that cattle are exposed to while at pasture and can effect their reproducitve performance.

In the pre-recorded video below, Cara Sheridan (Technical Advisor – MSD Animal Health) outlines the effect of Leptospirosis disease on cattle performance and mechanisms by which Leptospirosis can be controlled.

Leptospirosis is one of the most common causes of abortion in cattle in Ireland. It is an endemic disease, meaning that the majority of herds test positive for it.

Leptospirosis is a zoonotic disease meaning it can cause disease in humans. Leptospirosis can be acquired from contact with urine, afterbirth or aborted foetus of an infected animal. Esentially, all those working with stock are potentially at risk. Clinical signs of the disease in humans are flu-like, with headaches and fever, occasionally progressing to meningitis.

  • There are two serovars of Leptospirosis commonly found in cattle in Ireland;

Leptospira interrogans hardjo and Leptospira borgpetersenii hardjo

Leptospirosis circulates in a herd by direct transmission from infected animals (new infections or carrier animals) or by indirect transmission through urine, birth fluids, milk, contaminated water or other species e.g. sheep. Leptospirosis is very difficult to eradicate as some cows can become carriers. Leptospires can also survive for up to six weeks in wet soil and stagnant water or slow moving streams.Clinical Signs of Leptospirosis

Early signs are usually mild and transient and therefore may go unnoticed.

The most common clinical signs include;

  • Milk drop – A sudden decrease in milk yield
  • Abortions – Usually occur 6-12 weeks after the initial infection.

Abortion rates may be up to 30% in a herd infected for the first time.

  • Infertility – Low pregnancy rates and therefore increased culling due to low fertility
  • Weak calves – Infection in late pregnancy can result in the birth of weak calves that die within a few hours of birth

Diagnosis of Leptospirosis

Based on;

  • Blood sampling and looking for high antibodies level in affected animals (which can prove difficult as often the infection were present 6-12 weeks before clinical signs become apparent e.g. low pregnancy rates picked up at scanning)
  • Culture of urine samples
  • Leptospiral abortion diagnosis is best based on finding bacteria in the foetus

Speak to your vet about investigating Leptospirosis in your herd.

Control of Leptospirosis

  • Isolation of the sick cow and aborting cow
  • Biosecurity  – Avoid the introduction of infected animals
  • Quarantine until test negative
  • Double fencing at perimeters
  • Vaccination – The only practical way of controlling Leptospirosis

Timing of Vaccination

It is essential to vaccinate heifers before their first pregnancy. The primary vaccination course consists of 2 injections 4-6 weeks apart and thereafter an annual booster before turnout and at least 2 weeks before breeding.  It is a 2ml dose, given under the skin to all cattle >1 month of age. The correct use and timing of vaccination are vital to their success, always read the manufacturers recommendations.

Why vaccinate with Leptavoid-H?

  • Leptavoid-H is the only vaccine licensed to protect against both strains of Leptospira hardjo
  • Leptavoid-H is the only vaccine that is licensed to improve conception rates where Leptospirosis has been diagnosed as a cause of infertility
  • Leptavoid-H can be used on the same day as Bovilis BVD (to cattle >8 months of age)

BVD eradication – Update and control measures

The incidence of BVD among Irish herds has declined dramatically since the introduction of the eradication programme in 2013. In 2013, there was 16,194 cattle identified as positive for BVD. In 2019, there was 1,109 cattle identified positive for BVD. As of week 11 2020 there has been 183 animals identified as positive for BVD in comparison to 229 for the same period in 2019. While these results indicate great progress has been achieved in eradicating this disease, these figures show that the virus still circulates in our national herd. To ensure this disease is eradicated we must continue our approach, as outlined below, at farm level since the introduction of the eradication programme.

How does BVD spread?

This mainly occurs by nose-to-nose contact between infected cattle within the herd. Introduction of infected animals (either transiently or persistently) to the herd provides the greatest risk. Contact with infected animals from neighbouring farms, at marts or shows and during transport facilitates spread of disease. Animals can be infected by exposure to contaminated equipment, other species including sheep or by visitors to the farm.

What is a transiently infected (TI) animal?

Acute or transient infection occurs when an animal becomes infected for the first time at any point in its life after it is born. The animal may scour and occasionally it can result in death of the affected individual but often this infection is not associated with any obvious signs. When animals are transiently infected with BVD their immune system recognises the disease and responds by producing antibodies to protect against the effects of BVD.
Transiently infected (TI) animals test virus positive at the time of infection but become virus negative within 3 weeks after infection. Once TI animals become clear of BVD virus they are no longer a threat to the rest of the herd. The majority of PI animals are born to cows which were transiently infected in the first 4 months of pregnancy.

Why do I need to vaccinate if I am testing all calves and removing PI’s?

Removal of PI animals will decrease the amount of virus circulating within the herd. However, if cows are not protected during pregnancy, transient infection during the first 4 months of pregnancy can result in the birth of future PI calves. The most effective approach to BVD control within the herd is to test and eradicate PI carriers, vaccinate to protect pregnant cows and be vigilant regarding biosecurity. On-going monitoring to ensure the herd control measures are working, form the last critical aspect of a comprehensive control plan.

Bovilis BVD Vaccination Protocol


8 CRITICAL POINTS RELATING TO BVD ERADICATION

  1. Tissue tag testing remains compulsory in 2020.
  2. Take tissue tag samples from all calves as soon as possible after birth.
  3. Submit samples to a designated laboratory.
  4. Tissue tag and test all calves born including still births.
  5. Carry out all necessary follow up testing once a PI is identified e.g. test dam of PI. If the dam is also positive all her other offspring must be tested. Where a decision is taken, based on veterinary advice, to re-test the calf, this must be done by means of a blood sample only (this also applies to testing of dams). DAFM will meet the costs of the visit by the herd’s veterinary practitioner and of testing the calf (and dam
    if sampled at the same time).
  6. A PI animal should not be sold but should be isolated and culled at the earliest opportunity. DAFM will automatically restrict movements into and out of herds that retain PI animals for more than 21 days after the date of the initial test (in the absence of a recorded date of death on AIM). DAFM supports for removal of PI calves remain at the following rates:
    a. BEEF HERDS:
    i. €220 for beef breed animals removed with a registered date of death on AIM within 10 days of the initial test, reducing to €30
    if removed between 11 and 21 days after the initial test.
    b. DAIRY HERDS:
    i. Dairy heifers and dairy cross calves: €160 if removed within 10 days of the initial test, reducing to €30 if removed between 11
    and 21 days after the initial test.
    ii. €30 for removal of bull calves within 14 days of the initial test.
    It is anticipated that from 1st April 2020, there will be a legal requirement to test pre-2013 born animals.
  7. Vaccinate all breeding animals before service each year to protect against infection.
  8. Maintain high level biosecurity and continue monitoring to ensure freedom from disease.

To find out more about BVD vaccination, please contact your veterinary practice.

Use Medicines Responsibly
Bovilis® BVD Suspension for injection for cattle vaccine contains inactivated antigen of cytopathogenic
BVD virus strain C-86.
Legal categories: ROI: POM (E) . NI: POM-V . Withdrawal period: zero days.
For further information please contact your vetinary practioner or MSD Animal Health Technical Team,
MSD Animal Health, Red Oak North, South County Business Park, Leopardstown, Dublin 18, Ireland.
Tel: +353(1) 2970220. E-Mail: vet-support.ie@merck.com
Web: www.msd-animal-health.ie