In Part 1 of our blog on winter vaccination we covered the general principles of vaccination, including vaccine choice and correct storage and handling. In Part 2 we will look in more detail at vaccination protocols using the example of vaccination against bovine respiratory disease (BRD).
Once a decision has been made to vaccinate it’s important to have a vaccination protocol which should be made available to all those responsible for vaccinating the animals. It may seem obvious advice for larger units, but even on smaller farms it can’t be stressed enough how important clear written protocols are in ensuring mistakes aren’t made.
- Which – List of animals that need vaccinating
- When – Age of animal/time of year
- What – Select the correct vaccine
- How – Volume required, route of administration and interval between doses if a 2 dose course is required
I mentioned at the outset that in this blog we would look more specifically at vaccination against Bovine Respiratory Disease (BRD). This is a useful disease to review all the points we have covered because it’s a complex disease, caused by multiple pathogens, with other factors (housing, ventilation etc.) playing a key role. And given the time of year it’s also highly topical. The impact of BRD on production systems can be tremendous in the short and longer term. The longer term impact arguably causes the greatest losses. In beef calves these include ongoing reduced daily liveweight gains1(meaning delays to finishing or a lighter carcass weight) and carcass downgrade. For the dairy heifer calf these include increased age at first calving2, a reduction in lactation yields3 and a reduced longevity in the herd4.
The causes of BRD are multifactorial. Viruses such as BRSv, PI3v and IBR can act individually or in combination as primary pathogens to cause signiﬁcant lung and airway damage reducing the animal’s resistance to secondary bacterial infection. BVD virus is an important trigger for many diseases through suppression of the immune system. By protecting against these four viruses, we can clearly have a dramatic effect on protecting the respiratory health of our calves.
We’ll look at some example BRD vaccination protocols to show some of the considerations we take into account which help inform the decision around which vaccine and which protocol is most suitable.
Example Vaccination Protocols for Protecting Calf Respiratory Health
Option 1- most suitable for home-bred spring born suckler calves
Weaned and housed in autumn, these calves will be over 3 months of age at housing and ideally want protection throughout the winter months. Where no testing has been carried out, or animals are bought-in, broad cover is advisable.
Rispoval®4 may be a suitable vaccine for these animals since it provides broad cover - protecting against all 4 key BRD viruses - BRSv, Pi3v, BVDv and IBR (the BRSv and Pi3v components are live) , and protection lasts for up to 6 months, ensuring cover throughout winter housing.
As shown in the diagram, this vaccine requires two doses to be given 3-4 weeks apart with the vaccination course completed at least 2 weeks before the risk period (i.e. housing). Whilst from a management perspective it’s understandable that giving the second dose at housing may be more convenient, this means that the calves are not fully protected until 2 weeks into the housing period. In the authors experience it is not uncommon to see BRD problems during this period. So for farmers who absolutely cannot complete the vaccination course 2 weeks prior to housing, option 2 may be more appropriate. This requires some compromise to the breadth and duration of cover so you should discuss with your vet which option is most appropriate for you individually and for your farm.
Option 2 - Most suitable for bought-in calves or as an alternative option for spring/ summer home-bred calves where fast onset protection is required
For bought-in calves not vaccinated pre-sale the challenge lies in protecting them quickly enough. In these situations a 2 dose vaccine programme may not be appropriate. More rapid protection can be provided by using single dose vaccines delivered intranasally. This applies equally to home bred calves where more rapid cover is required. This speed may however come at the expense of breadth and/or duration of cover.
For example Rispoval® IntraNasal, a single dose live intranasal vaccine, will protect calves against 2 viruses, BRSv and Pi3V in just 5 to 10 days, and cover for 12 weeks. Tracherine® another single dose live intranasal vaccine will protect calves against IBR in just 4 days and cover for 6 months. The compromise is that compared to Option 1, there is no cover against BVDv, and cover against BRSv and Pi3v is for 12 weeks vs 6 months. Decisions on vaccine choice clearly involves many factors, including how they will fit into your management system. The best vaccine in the world may not be appropriate if for whatever reason you will be unable to administer it according to the label instructions.
Option 3 - For autumn born suckler or dairy /dairy-bred calves
These calves are often born into a higher risk environment so priorities are likely to be a vaccine which can be used early, works in the presence of colostral antibodies, and which works fast to provide protection and minimise pathogen loads in the shed.
Rispoval® IntraNasal, for example, is a single dose vaccine which can be used from just 9 days of age, and since delivered via the intranasal route it works in young calves, and it works in the presence of colostral antibodies, meaning it provides the earliest possible protection against 2 key BRD viruses BRSv and Pi3v.
The compromise here is that it does not include cover against BVDv and IBR, and protects for at least 3 months (vs 6 months for Rispoval 4 ). Importantly this vaccine works fast (which is arguably the highest priority in these young calves) ensuring they are protected over a critical risk period. This vaccine may be all that is required to get calves on their way, but if ongoing cover is needed follow on vaccination can be carried out as below. Again this depends on each individual farm so is a discussion to be had with your vet.
Why Do Things Go Wrong Sometimes?
Inevitably on occasion disease occurs despite use of a vaccine programme. It’s worth exploring the reasons why this could happen;
- The wrong number of doses were given: the most common problem being failure to complete a 2 dose primary vaccine course. The appeal of single dose vaccines is obvious to see.
- Incorrect inter-dose interval during a 2 dose primary vaccination course: the time interval which should be applied between the first and second doses will be stated on the product information sheet. It’s commonly between 2 and 4 weeks. If the interval is too short or too long the response to the second dose may be less than expected, potentially resulting in a reduced level of protection, or reduced duration of protection.
- Wrong age of animal: some vaccines are either not licensed for use in young animals, or are licensed but have no information on how effective the vaccine will be if the calf has colostral antibodies. Ensuring calves receive sufficient good quality colostrum is a vital part of good calf management, but those same antibodies can interfere with some vaccines.
- Wrong timing: too near risk period:this is a common problem when vaccinating youngstock prior to winter housing. No vaccine works immediately, they all have a period of time (known as the ‘onset of immunity’) before they provide effective protection.
- Losing track of which animals are done or which need a second injection or forgetting the booster vaccination.
- Unrealistic expectations! Vaccination should be used as part of an overall disease control strategy, and should not be used to prop up poor management practices. In the face of overwhelming challenge the immunity gained from vaccination may simply not be enough to prevent disease.
Vaccination plays a key role in protecting the health of our livestock. Vaccines are an investment in terms of cost and labour, so plan ahead and make sure that you get the most from your vaccines by storing and using them correctly.
Williams P., Green L. (2007) Cattle Practice Vol 15 Part 244-248 (‘moderate BRD’-3 consolidated lung lobes, ‘severe BRD’- 6 consolidated lung lobes)
Van Der Fels- Klerx, H.J. et al. (2002) Livestock Production Science 75, 157-166
Morrison S., (2011) Zoetis Conference Rhodes (www.afbini.gov.uk)
Bach A., (2011) J Dairy Sci 94(2), 1052-1057
Rispoval® RS+PI3 IntraNasal contains modified live Bovine PI3 virus and BRSV. POM-V.
Tracherine® contains live attenuated Infectious Bovine Rhinotracheitis (IBR) virus strain. POM-V.Rispoval®4 contains attenuated strains of BRSv and PI3 viruses supplied together with a suspension containing inactivated, adjuvanted IBR and BVD cytopathic and non-cytopathic Type 1 viruses. POM-V.
For further information please see the product SPC, or contact your veterinary surgeon or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. http://www.zoetis.co.uk/. Always seek the advice of your medicines provider. Use medicines responsibly (http://www.noah.co.uk/responsible).