Most of our livestock diseases are infectious, spread by carrier animals or via the environment.

The pig and poultry industries have been practising excellent biosecurity and disease control for decades, with high stocking densities and valuable populations – these industries operate a zero tolerance to disease, with strict health status, hygiene, and comprehensive vaccination protocols.

Disease outbreaks are potentially catastrophic, requiring whole population culls. Showering before entering and leaving facilities is common practice, as is wearing specific clothing and boots. Staff salmonella screening is undertaken, maintaining disease freedom.

Livestock movements

Livestock movements are still the greatest threat to disease control. Operating closed herds and flocks greatly reduces the risk of new diseases being introduced onto holdings.

Bovine TB, BVD, IBR, Johne's, salmonella, contagious abortions and lameness are just a few examples where major risks are associated with livestock movements.

Operating a truly closed business may be difficult to maintain, therefore any livestock joining a holding must be from a known health status.

Quarantine of added animals, pre- and post-movement testing for disease, should be undertaken together with vaccination and parasite treatments before joining the main herd/flock.

Neighbouring livestock

This can also be seen as a significant biosecurity risk. Stock-proof three-metrr boundary fencing will prevent nose-to-nose contact.

BVD and sheep scab would be highly infectious diseases easily spread from neighbouring livestock. Shared water courses are known to be a risk too, especially for spread of lepto, Johne's and salmonella.

Preventing access to open water and providing mains drinking water troughs would reduce this risk.

Housing management

Another fundamental point to disease control is housing management. Pig and poultry units operate strict disinfection procedures to prevent environmental build-up and spread of disease.

Empty buildings are thoroughly cleaned and disinfected between groups of animals. Multiple disinfectants are used to kill different bacteria, viruses and protozoa.

Ensure these products are used on clean surfaces at the correct concentration and contact time. Many disinfectants just kill viruses and bacteria, but specific agents must be used to kill protozoa like coccidia and cryptosporidia oocysts.

Batch rearing

Another way to dramatically reduce disease risk is through batch rearing, especially dairy youngstock and store cattle rearing.

Keeping livestock in stable management groups, preventing mixing with older and younger animals of different disease status and immunity, offers the healthiest environment to maintain health and reduce disease. Ideally these environments should not have contact or sheared airspace with adult animals.

Winter housing

Winter housing of sheep is known to be a risk factor for the spread of respiratory disease like OPA. Stocking density, shared troughs and mixed age groups are likely to increase the spread of disease.

Salmonella outbreaks can be devastating, causing serious scours, septicaemia, abortions and death. Salmonella strains behave differently. Carrier animals may introduce new infection – 2% of cattle can be carrying salmonella without showing any symptoms – but vermin, birds, humans and contaminated feed are also common sources of infection.

Key events

Livestock shows and markets are key events for advertising and selling stock but also a significant disease risk too.

Animals of different disease status can travel the length of the country and back to attend shows and sales. Some well-established schemes like the MV accreditation in sheep maintain biosecurity by only allowing members of the scheme to attend shows and sales. Unfortunately, there are still many contagious diseases that are commonly spread at these events.

Organisers of shows and sales should promote disease testing and freedom. Being aware of the risks, proactive health schemes and quarantine will help reduce the risks of bringing in new diseases.


Vaccination is still an underused but valuable way of reducing the risks of introducing new infections into herd and flocks.

In Scotland, we are making progress in the control of BVD in breeding herds, with effective monitoring methods in place to ensure detection of disease breakdowns.

As BVD becomes less of a perceived risk, it could be deemed that vaccination is no longer necessary.

Unfortunately, BVD is still very common and uncontrolled in large parts of England and due to the high contagious nature of the disease, the threat to Scottish herds is a serious risk.

Continued effective vaccination programmes and pre/post-movement testing including newly-born calves are essential until our neighbours have done more to control BVD.

Biosecurity risk

Biosecurity risk is such an important area in animal health and should never be overlooked.

Learn from our colleagues in the pig and poultry industry and ensure that you have a comprehensive biosecurity plan in you herd and flock health plans.

Your vets have access to excellent online resources to help you discuss the risk factors specific to your business.

Remember, livestock movements are the single biggest risk associated with new diseases.

It is important to know your current disease status and protect it through proactive health schemes, vaccination programmes, and pre- and post-movement testing.