Vaccinating Chickens

Should I vaccinate my flock? This is a question often faced by vets in practice and the answer is often a complex one. Firstly, let’s look at what a vaccine is.

A vaccine is made up of either an inactivated form of the organism that causes the disease you are trying to prevent or a live vaccine which contains a version of the organism that is less dangerous to the animal. Live vaccines tend to provoke a better immune response by the animal but immunity last for shorter period compared to inactivated vaccines which creates an immune response that lasts longer but tends to be less effective.Vaccinating Chickens

First we should look at why there may be a need to vaccinate. Often the main reason for wanting to vaccinate is to prevent a disease from entering or to prevent the symptoms of a disease already present in a flock.

The best disease prevention method is biosecurity! Simple protocols such as buying in birds bred from stock that have a high health status (as clear from as many diseases as possible at the time of purchase) and regular cleaning out of coops, feeders and drinkers with a good detergent and a disinfectant will also help keep pathogens to a minimum.

If your biosecurity is in tip-top order and can be improved no further then there may then be room for a vaccination protocol.

What can we vaccinate against?

Commercially there are many disease which we can try to prevent using vaccines, however in backyard flocks situations it is often only necessary if at all to vaccinate against the very common diseases. Below is a list of the vaccines most commonly used in backyard flocks:

  • Marek’s Disease
  • Avian Rhino Tracheitis
  • Infectious Bronchitis
  • Salmonella
  • Mycoplasma Gallisepticum

What should I vaccinate against?

Respiratory disease is a common problem faced by keepers and is most often but not exclusively caused by one or a mixture of Mycoplasma species, Infectious Bronchitis or Avian Rhino Tracheitis. In order to know which vaccine to use it is always best to identify which pathogen your birds are suffering from. To identify the possible causative pathogen a blood test is most likely needed, this will test for the three most likely pathogens and will guide you as the keeper and your vet as to which pathogen to vaccinate against.

If vaccinating is needed then two doses given via intramuscular injection spaced 4 weeks apart and subsequent annual boosters are necessary.

Marek’s disease is a disease owners often want to vaccinate against as the effects of the diseases are particularly nasty and can be life long in your flock. However if your flock has had no previous symptoms suggestive of Marek’s and you do not buy in birds regularly from unknown disease status flocks then we generally advise against vaccinating.

Vaccinating a cockerelSalmonella is a pathogen well-known to many people and commercially there are many protocols and systems in place to try to prevent the development of salmonella infections. The vaccination protocol is similar to the respiratory vaccines. However the vaccines used tend to only protect birds against infections from two species of salmonella and there are several other strains of salmonella that are not protected by the vaccine, this is a major cause as to why it is generally not necessary to vaccinate in back yard flocks. If high hygiene practices are in place when handling chickens or processing items such as egg or meat then there should be minimal risk to the keeper from salmonella.

When to vaccinate?

It is always best to vaccinate birds from day olds when they have not already been exposed to the pathogen which the vaccine is trying to prevent. Vaccination via injection for Marek’s usually occurs at day olds and respiratory pathogens such as mycoplasma gallisepticum, avian rhino tracheitis or infectious bronchitis can be given at point of lay.

chicken vaccination
A commercial chicken being double vaccinated.

Often owners would like to vaccinate their birds when they buy them and they are unsure of their age. The main problem with this is that there is an unknown history of the bird and to what pathogens the bird may have already been exposed to.

Birds that are brought from market may already have for instance the virus that causes Infectious Bronchitis, therefore vaccinating the bird would in the keeper’s eyes be a fit and healthy vaccinated bird but in actual fact it could be shedding IB virus and infecting the rest of the flock. In this instance the gold standard would be to test (via blood) whether or not this bird had had a challenge of IB and whether or not it is worth vaccinating.

Where to get vaccines from?

If you decided that vaccinating your flock may be an option then vaccines can be ordered through vets such as St. Davids Poultry team Ltd, Vaccines are usually produced in large quantities for hundreds of thousands of birds but St. Davids can break them down into 1000 bird doses that are relatively well priced.

It is always worth remembering that vaccines are not always 100% effective at preventing the disease for which they are made. There are many complex reasons as to why some vaccines may not work, and for this reason it is always recommended to speak to a trained person such as a vet who can tailor make a vaccination protocol for the flock and environment for which the birds are kept. Birds should also not be injected with vaccine without prior training as a lot of damage and potential welfare issues can arise if a bird is vaccinated incorrectly

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Kenny Nutting BVetMed MRCVS

Kenny studied at the Royal Veterinary College in London and works for St. David's Poultry Team AKA Chickenvet.

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