Alistair Chilcott BVetMed MRCVS
Grazing cattle, in both dairy and beef systems, are at risk of this costly disease (HUSK) during the autumn months, with the risk period increasing due to changing weather patterns. So why worry now?
Because last Autumn we saw several cases of Lungworm and now is the time to implement an effective preventative management strategy to avoid the potential cost of a HUSK outbreak.
HUSK outbreaks have resulted in:
- Loss of milk yield – an average of 4kgs/cow/day
- Decreased fertility – calving intervals increased by 30 days
- Lost body condition score – over 1 BCS loss across a herd
- Deaths – over 10% of a herd being lost
Effective Lungworm control relies upon strategic grazing patterns, the responsible and appropriate use of wormers (anthelmintics), and vaccination (Bovilis® Huskvac).
Silent “carrier” animals are the major source of Lungworm infection from one year to the next, with heifers carrying over more larvae than cows. It is estimated that 1 in 5 outbreaks of disease are due to overwintered larvae on pasture. Some larve can live in pasture for several years before migrating up a grass leaf to be eaten. Outbreaks are often seen after a dry period followed by a big storm that enables grass to grow rapidly.
If using anthelminitics/ wormers in youngstock to control normal gut parasites (stronglyes) during the whole of the first or second grazing season then usually this is effective in preventing HUSK in these animals. However, the problem with this approach is that animals will not have the opportunity to develop an effective immune response to Lungworm when they are young. When anthelmintic protection does not cover the entire grazing season, non-immune animals are at risk.
Animals that enter the main herd with a good immunity to Lungworm remain at risk of HUSK as adults.
An effective vaccination against Lungworm has been available since the late 1950s, now known as Bovilis® Huskvac. Appropriate use of this vaccination establishes a reliable immune response, avoiding the worry associated with the previously mentioned at-risk animals.
A few key points to remember when using Huskvac:
- Licensed to be used from 8 weeks of age
- A primary course requires 2 doses orally, 4 weeks apart, with onset of immunity after 2 weeks following the second dose
- Primary vaccination courses need to start 6 weeks before turnout
- This vaccine contains live attenuated Lungworm larvae, therefore do not worm animals within 2 weeks of vaccine administration – this will kill the larval vaccine, and stop it from working!
- Following vaccination, immunity should be “topped up” by natural exposure to Lungworm during the grazing season
- If this exposure does not occur, a booster may be required
Early spring is the time of year to engage with your vet to develop an appropriate management strategy for your system against this disease, and we would always advise putting a plan in place making the most of the effective vaccine available to prevent this unpredictable and destructive disease.