Vaccination: one jab or two?

For many livestock vaccines, two doses are required to provide adequate and long-lasting protection.
For many livestock vaccines, two doses are required to provide adequate and long-lasting protection.

The development of vaccination is surely one of the biggest breakthroughs in medical history. In the world of human health, it all started with a few milkmaids in the 1700s. Doctors noticed that these milkmaids seemed to be protected from the potentially deadly smallpox.

It was eventually discovered that it was exposure to cow pox – a similar but much less severe disease – which provided them with protection.  How were the milkmaids exposed to cow pox?  These were the days of hand milking.

‘Vaccination’, this ability to use a small dose of a particular bug which has been killed or modified so that it’s harmless, is a powerful tool. 

We sometimes take it for granted, but vaccination has also played a big role in livestock health.  It provides livestock producers with cheap and effective insurance against a range of diseases. 

In my job as a District Vet I often deal with cases which could have been prevented by the right vaccination program.

The first question to consider is which diseases to vaccinate for.  Both sheep and cattle should be vaccinated for what are called ‘clostridial’ diseases.  This group of bacteria includes some particularly nasty ones, such as those which cause ‘pulpy kidney’, ‘black leg’, and tetanus.

Clostridial diseases like pulpy kidney can develop quickly and often cause sudden death.  For that reason, they’re difficult to effectively treat, so vaccination is a really useful option.  Prevention is certainly better than cure.

Tetanus is a bug which can survive quite a long time in the environment, and can infect wounds such as those associated with lamb or calf marking.  I’ve seen a number of cases of tetanus in unvaccinated sheep and cattle.  Unfortunately unless it’s caught early it can be difficult to treat effectively.

A number of products are available which cover these clostridial diseases.  The common “5-in-1” (so named because it covers 5 clostridial diseases) is probably the best known example.

While a clostridial vaccine should be given routinely to all stock, there are a range of other options.  Vaccines are available for leptospirosis, pestivirus, botulism, erysipelas arthritis, Johne’s disease, cheesy gland, scabby mouth, vibrio in bulls, and even pinkeye. 

Which ones are necessary? The right choice will depend on your enterprise type, disease history, and environment, amongst other things. 

VACCINATION: First arrow: first dose. Second arrow: second dose.

VACCINATION: First arrow: first dose. Second arrow: second dose.

Another question I’m often asked is, “if the label says to give two doses, can I get away with just the one?” Although this approach is tempting, it simply isn’t effective. The diagram above shows why this is the case – without the follow up dose (given around a month after the first, for many vaccines) immunity quickly falls away. It’s the second dose which boosts immunity to provide maintained protection. In the long term, giving one dose of a vaccine which requires two is about as effective as doing nothing. So next time you’re picking up some vaccine, have a think about what program is best for your farm. Done right, vaccination is cheap and effective insurance.