News & Advice

Increased risk of disease this season

Apr 11, 2023 | Biosecurity, Dairy

Your farm’s biosecurity plan is more important than ever this year and should not be left to chance.

There are many reasons why this season’s wet weather could result in an increased risk of disease – some are obvious, some less so. More animals have been moving between farms already this year, either to get animals off flood-affected land or perhaps simply to take advantage of an over-supply of grass on other, unaffected properties. As we get closer to June 1st, we will continue to see stock being moved around the country for the annual shift to grazing and home again for calving.

Whatever the reasons are behind the animal movements, there are some additional risks this year that should be considered in your biosecurity plan this year to protect animals already present on the property from the potential of introduced disease, but also to protect incoming stock from diseases (including those they could take back to their home property at the end of their stay!).

We’ve put together a list of diseases to keep in mind and importantly, what you can do about them:



Leptospirosis – this one is a biggie this year – not only because it can cause clinical disease (including abortions) in animals, but also because it is a serious zoonotic disease meaning it passes from animals to humans, making humans very unwell too. Flooding increases the risk of leptospirosis as the lepto bacteria love living in wet environments.

What can you do to manage the risk?

      • Recognise the signs of disease – leptospirosis can be mistaken for other diseases as the clinical signs aren’t always specific – abortion, milk drop, “red water” (red coloured urine), fever, conjunctivitis, jaundice are all features of lepto but can also be seen in other diseases. Keep lepto in mind if you see any of these signs in your animals and contact your vet for advice.
      • Vaccination – make sure all animals are fully up to date with their lepto vaccinations to reduce the chances of them picking up a new infection. Have a read here if you want to know more about Why do we vaccinate against Leptospirosis? Anexa.
      • Pest control – rodents are known to increase the risk of spreading lepto both between animals and from animals to humans. Make sure your pest control is up to scratch particularly around stored feed (e.g. meal).
      • Protect yourself – lepto is a really nasty disease in humans and you don’t want you or your staff getting sick. Make sure everyone wears appropriate footwear at all times on the farm. Don’t eat, drink or smoke in the cowshed (when you are most likely to get splashed when cows urinate) and cover any cuts & grazes with waterproof plasters or gloves.
      • Talk to your Anexa vet to arrange a Lepto Risk Assessment consult for your farm.



BVD can affect animals of any age. Pregnant cows that catch BVD or are PI (persistently infected) can lose the calf (abortion), give birth to sick/weak calves or pass on the infection to the unborn calf who goes on to be born looking fine, but will actually be infected for life (PI) themselves.

What can you do to manage the risk?

      • Know the BVD status of any animals coming onto your property – only accept animals you know have been tested as being PI-negative.
      • Vaccinate any animals leaving your property to go grazing and consider whether animals at home should also be vaccinated – your vet can sit down with you to assess the BVD risk on your farm and put in place appropriate management strategies protect you current and future animals.



Salmonella – another unpleasant zoonotic disease that can cause both devastating animal health and human health problems. Salmonella can spread through water, so a wet year (especially with flooding) increases the risk of salmonella affecting previously uninfected properties. Stress of any kind will increase the chances that carrier animals will start shedding bacteria and become unwell.

What can you do to manage the risk?

      • Signs of disease can range from animals being mildly ‘off colour’ to profuse diarrhoea (often smelly) through to sudden death.
      • Vaccination is a cost effective way to reduce the risk and severity of disease.
      • Protect feed sources and troughs from birds and rodents and fence off flooding and areas of standing water from stock.
      • Protect yourself – be very aware of hygiene around sick animals – wash hands, wear gloves, don’t eat, drink or smoke around sick animals.


Staph aureus

Staph aureus… and other contagious mastitis bugs – if you are buying or leasing cows, or simply milking someone else’s cows for a while, do you know what bugs they might be bringing with them? You don’t want to introduce a new mastitis problem – especially if it brings antibiotic resistance genes with it!

What can you do to manage the risk?

      • Ensure you have milking management systems in place that will reduce the risk of spreading any bugs during milking (e.g. milk newly introduced cows last; teat spray every cow, every milking; all staff wearing gloves etc.)
      • Ask the farm of origin if they have Dairy Antibiogram (DAB) results for their herd and carry out a DAB on your own herd so you know the current antimicrobial resistance status – talk to your vet if you want to know more.
      • Chat to your vet during your milk quality consult about what you can do to minimise the risk of spread of mastitis bugs.


Johne’s Disease

Johne’s Disease – another hidden disease that could cause long-term negative impacts on your herd if accidentally introduced. Johne’s is incurable once an animal is infected. Calves are most at risk of picking up new infections.

What can you do to manage the risk?

      • Know the Johne’s Disease status of the herd of origin of the new cows.
      • There are a range of tests available to test animals for Johne’s Disease.
      • Talk to your vet to develop a management plan to prevent calves coming in contact with infected material (milk or faeces). Read more here Johne’s Disease – why are we worried about it? Anexa


Clostridial disease

Clostridial disease including Blackleg – many clostridial bacteria live in soil. Anything that disturbs that soil (floods, earthquakes, ground works etc.) can release clostridial spores increasing the risk of disease in animals.

What can you do to manage the risk?

      • Vaccination – ensure all calves have been fully vaccinated with both a sensitizer and booster. High risk areas may require a more comprehensive vaccine covering 10 strains of clostridium (rather than 6 strains in the more commonly used vaccine). Older animals should be given an annual booster in high risk areas.



Worms – don’t forget about those internal parasites. Calves will continue to need regular worming throughout autumn and winter. Chat to your vet if you need any advice about the parasite management in your animals.


There is a lot to think about when considering good biosecurity measures on farm. Book a chat with your vet to talk through the specific risks on your farm or read more about Anexa’s Biosecurity Risk Assessment here. We know every farming situation is different – we can work with you to make a tailored approach to keep your animals as healthy as possible.

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