Lungworm infection is diagnosed annually by SAC Veterinary Services. Cases are now being seen nationwide. Cattle of all ages can be affected although weaned calves at grass are most at risk. While the majority of cattle survive infection the disease can be fatal. Animals at greatest risk are calves in their first grazing season and yearling animals entering their second grazing season.
Prevention of lungworm infection is possible either by vaccination or by repeated wormer use but this can encourage wormer resistance. The only lungworm vaccine available is Bovilis Huskvac (MSD Animal Health). The vaccine is given by mouth and contains lungworm larvae that cannot develop into adults but are able to migrate and trigger an immune response.
The data sheet for the vaccine states that calves can be vaccinated from eight weeks of age onwards. The primary vaccination course involves two doses of the vaccine four weeks apart. The data sheet also recommends the second dose should be given at least two weeks before calves have access to pasture. Vaccination should be considered for (a) spring-born calves in their first grazing season; (b) yearling breeding heifers entering their second grazing season.
Spring Born Calves
- Within the context of a spring-calving beef herd the recommended data sheet protocol is unworkable, as it would require March-born calves to be held off pasture until mid-June at the earliest. A more practical solution is for calves to go to grass unvaccinated and then start the primary vaccination course when they reach eight weeks of age. Calves can be vaccinated at any stage throughout the summer, as long as they receive their second dose of vaccine at least 2 weeks prior to weaning. It is important to note that SAC would always recommend discussing any off-data sheet vaccine use with your vet prior to vaccine use.
Yearling Breeding Heifers
- Bulling heifers are at particular risk in their second grazing season if they have received limited exposure to lungworm in their first grazing season. Establishing exposure can be difficult, especially if heifers are purchased. Given the value of these animals to the breeding herd it is worth considering vaccination as a routine part of the herd health plan. The standard data sheet protocol can be used (as detailed above) with the primary course being completed at least two weeks prior to turnout. Discuss this with your vet as soon as possible in order to implement vaccination at the right time.
It is recommended that vaccinated calves are exposed to pasture carrying a low level of lungworm larvae, as this will enhance the immunity provided by the vaccine. Also, in order for the vaccine to be most effective, it is important to avoid crossover between wormer activity and vaccination and to avoid wormer use for two weeks after vaccination.
Lungworm immunity is maintained from season to season by exposure to lungworm larvae, which in most cases occurs from the grazing of normal pastures after vaccination. A single dose of vaccine prior to each season’s turnout will boost immunity where such exposure has not occurred. Reasons for this may include extensive use of wormers, or use of reserved or clean pasture for a large part of the grazing season.
David Gibson, firstname.lastname@example.org
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