PARASITE FORECAST October 2013 – Summary

Local farm conditions may change, consult your vet. Effective worm control should be part of your veterinary health plan

For the full forecast please go to www.nadis.org.uk

LIVER FLUKE FORECAST

Watch out for: risk of high prevalence of liver fluke disease in north and west; occasional losses over rest of UK

Early infections this year have led to large numbers of ewes and lambs carrying adult fluke and shedding fluke eggs during September

Infection pressure may be reduced by fencing off wet areas or avoiding such pastures until around February

Sheep

Farms with a history of fluke will probably need to dose gazing sheep if not done already. It may be advisable to give a second fluke dose 4-6 weeks after the first, following veterinary advice.

Triclabendazole is usually the drug of choice at this time of year, although resistance to the drug appears to be spreading

Flocks with no previous evidence of fluke disease should monitor for the presence of infection via post mortem examination, abattoir feedback, blood sampling etc.

Cattle

Outwintered cattle may be treated in the autumn with a flukicide effective against young immature fluke

Cattle housed over the winter that have been exposed to infection should be dosed after housing; the interval between housing and treatment will depend on the product used. If closantel or nitroxynil are used, they may be given six weeks after housing to ensure that all flukes are old enough to be susceptible.

SHEEP NEMATODES

Prevention: use faecal egg counts to time dosing of lambs on contaminated pastures. Quarantine dose any new stock moving on to farm

The worm life cycle will be slowing down and larvae do not develop when it gets too cold, typically below 10 °C

Some larval development may occur throughout the year given a mild winter

Any lambs remaining on contaminated pasture should be dosed less frequently. Using FECs and other information to time doses is preferable to just giving regular anthelmintic treatments

Any stock still moving onto farms will need to be quarantined and treated; current best practice (as recommended by SCOPS) involves the use of two highly effective wormers from different groups; e.g. sequential full dose treatments with monepantel (Zolvix) and moxidectin,

followed by yarding for 24-48 hours, and turnout onto pasture recently grazed by sheep; i.e. NOT clean grazing

CATTLE NEMATODES

Watch out for: outbreaks of lungworm disease which often occur very suddenly especially following heavy rain after a dry spell

August to October is usually the peak period for lungworm disease in cattle

Only a small dose of Dictyocaulus is needed to instigate disease in susceptible animals, and locally wet conditions, especially thunder showers after a dry spell, can quickly increase pasture infectivity

Susceptible animals include:

o Unvaccinated spring-born calves before housing

o Unvaccinated yearling calves either after suppressive PGE control has finished or those animals on a dose and move system

o Older cattle that have not been exposed to regular small natural challenges to maintain immunity, perhaps following suppressive worming regimes in previous years

Dry conditions from June onwards in many regions may be associated with an increased risk of type 2 ostertagiosis this year

Moving calves in the autumn back onto pastures infected by calves earlier in the summer is also associated with an increased risk of type 2 disease

The problem should be straightforward to prevent; in general, all calves should receive a housing anthelmintic dose, ideally with a Group 3 wormer (ivermectin-type)

LICE IN CATTLE

Prevention: combined worm/louse dose is probably advisable when cattle are housed

Severe louse infestation may cause poorer liveweight gain due to interrupted feeding patterns.

Group 3 (macrocyclic lactone, ML) wormers are usually recommended for the housing dose in cattle due to their larvicidal activity and efficacy against lice.

Parasite Control should be part of your veterinary health plan, consult your vet

Parasite Forecast

October

NADIS

Sheep affected by acute liver fluke may simply be found dead. Sudden unexplained deaths must be investigated to confirm the cause

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Early signs of Type I ostertagiosis