Lameness vaccines in sheep

Lameness vaccines have their part to play in flock management to reduce the incidence of lameness on farm.  

Lameness in sheep flocks is one of the most common and persistent disease problems; scald, footrot (caused by Dichelobacter nodosus) and contagious ovine digital dermatitis (caused by treponemes) are common infectious causes. It is unrealistic to expect that a flock will never have lame sheep, but it is important that the infectious nature of lameness is fully understood so that careful control might prevent the number of cases from escalating.  

The cost: £24m per year for footrot (Nieuwhof G. J. 2005) and the overall cost of lameness in a flock is estimated to be between £3.90 and £6.35 per ewe per year (Winter J. R. 2017). 

The five point plan (Clements R. H. 2014) is the current sheep industry-accepted standard for lameness control. It summarises the tools that are available for lameness control in sheep flocks. 

The five point plan

1. Cull badly or repeatedly affected animals.

2. Quarantine incoming animals.

3. Treat clinical cases promptly.

4. Avoid transmission of infection on farm.

5. Vaccinate against footrot biannually.

With two-thirds of antibiotics used on sheep farms considered to be used in the control of infectious lameness (Davies 2017), improved lameness control is one of three hotspot areas for the reduction of antibiotics in the sheep industry, as identified in the RUMA Targets Task Force Report 2020. This target is to be achieved by increasing awareness and uptake of the five point plan. It has been estimated that footrot vaccination reduces the prevalence of footrot by 20–70% (Winter J.R. 2015) (Hindmarsh F. 1989) (Duncan 2012), though recent work suggests that lameness prevalence is only lower in flocks that have been vaccinating for over five years (Prosser 2019) (Best 2020).

There is evidence to suggest that farmers consider vaccination against footrot to be a reactive tool rather than a preventative measure (Best 2020), which may suggest why short-term vaccination (1–2 years) is actually associated with higher reported levels of lameness.

Only one footrot vaccine is available:

• Footvax is a vaccine for the active immunisation of sheep as an aid to the prevention of footrot and reduction of lesions of footrot caused by serotypes of D. nodosus  

Assumptions

Numerator: The number of doses of vaccine administered has been calculated by multiplying the number of packs sold by the number of doses per pack.

Denominator: Although there are flocks for which lameness is well controlled and footrot vaccination is not necessary, for the purposes of this report, it was decided that for a denominator that all ewes intended for first-time breeding should receive two doses of vaccine as a primary course and that older ewes would be vaccinated at least once a year. Rams appear to be particularly susceptible to infectious lameness and since the mobility of rams is critical to their breeding performance, it was considered that all rams should be vaccinated for footrot twice a year. The total number of vaccine doses that would be required to help prevent footrot in the national UK flock has been estimated based on the assumption that all ewes intended for first-time breeding and all rams should receive two doses of vaccine, and that all ewes intended for further breeding or slaughter receive an average of one dose. Ewes that are culled without being vaccinated are likely to be balanced by those ewes receiving additional doses in times of higher risk.

Vaccination uptake

In 2022, it was estimated that 16% of the breeding flock was vaccinated for footrot. This is decrease from 19.4% in 2021 due to vaccine supply shortages. The value is above the 2012–2021 average of 13%.