With farms all around the country opening trailers and gates to replacements, correct quarantine procedures – and sometimes the lack of them – as highlighted in the recent Farming Against Wormer Resistance (FAWR) campaign, will be a key topic amongst vets and SQPs.
Just under half of all farmers completing the campaign’s survey into worming practices were not separating incoming stock. 32% of farmers were not worming at quarantine, and of the 68% that did worm, well over half were using one active only. All these practices, highlighted in the Novartis Animal Health survey, are likely to increase the risk of spreading resistant worms. In fact only 25% used the recommended products and according to Lesley Stubbings, SCOPS representative and FAWR panel member, only 10% carried out an effective quarantine routine.
“Sheep farms are at their most vulnerable when they are bringing in stock from markets or other farms,” says Ms Stubbings. “Quarantine is the only effective defence against a number of serious health threats, including resistant worms and sheep scab. Even expensive sheep from reputable sources can still carry problems, – farmers can’t tell just by looking at them so the only way to be sure is to implement a rigorous quarantine protocol using effective treatments.”
The strategy recommended by SCOPS is to use two broad spectrum anthelmintics, both with the least chance of the worms in the sheep being resistant to them. SCOPS also recommends that all sheep are treated against sheep scab. Sheep should be yarded for 24-48 hours to allow any worms eggs to pass then moved to dirty pasture.
SCOPS Quarantine Strategy
- Quarantine (isolate) all incoming stock
- Yard for the first 24-48 hours
- Drench with 4-AD orange wormer or 5SI wormer plus inject 1% moxidectin while yarded
- Move to dirty pasture (that has carried sheep this season)
- Keep isolated from resident flock for as long as possible (minimum 3 weeks)
“The orange drench, monepantel, is an ideal choice for use as a quarantine treatment,” says Fiona Anderson, Novartis Animal Health Veterinary Manager. “There are no resistant worm populations in the UK so it is highly effective even against triple resistant worms. In the unlikely event that any worms have survived, moving sheep onto dirty pasture ensures that they will be diluted out by the worm population already on the farm pasture.”
FAWR, in addressing the growing concern about wormer resistance, worked closely with organisations such as SCOPS to promote greater understanding of the issues through improved contact between farmers and their advisors.
Appropriate wormers
Mike Glover, Veterinary Surgeon from Torch Farm Vets who, as a member of the FAWR panel and the Sheep Veterinary Society discussed the survey findings, said: “Whilst we can take some encouragement in that over half of farmers surveyed were isolating stock, and 68% of those were drenching, not all were treating with the appropriate wormers.
“20% were using white drench, which would have been ineffective in preventing the introduction of resistant worms. 62% were only using one chemical class, which again is disappointing. However, 38% were using the recommended two with 20% of those using Zolvix® and a 3-ML wormer. The sheep industry clearly is making progress, but there is still work to be done. As yet the message hasn’t quite reached that critical mass of farmers who will then persuade others that having an effective quarantine strategy in place is essential for a sustainable future in sheep farming.”
One of the main messages farmers need to accept is just how common resistance is. Various studies in the UK show BZ resistance on a high percentage of the farms tested, LV resistance is less prevalent, but ML resistance is now a much more common problem than previously thought.
Resistance is common
“At practice level, here in North Devon, we have been conducting Faecal Egg Count Resistance Testing with the support of Novartis Animal Health on over 20 farms in the practice,” continues Mr Glover. “With full results back on 15 farms so far we have only found one farm on which all three of the older wormer classes are still working fully effectively. In line with other surveys nearly all farms (13/14 tested) had BZ resistance and most also had resistance to more than one of the older classes. So, as elsewhere in the UK, resistance on our practice’s farms appears to be common.”
“As a practice, sheep farmers are aware that we are interested in helping them to develop more sustainable parasite control plans and in offering advice. The principles of sustainable parasite control can be more complex to apply now than the ‘blueprint approaches’ of the past so we try to discuss worm control with our clients throughout the year and adapt control plans regularly in response to seasonal weather patterns, the results of feacal egg counts and any clinical signs of disease.”
Quarantine – an investment
Another potential chink in the quarantine armour of any farm can be rams. “Purchased rams should not be overlooked as a potential source of resistant worms,” says Mr Glover. “Breeding rams may be treated more frequently with wormers to maximize growth rates during the rearing phase and we know that frequent treatment increases the selection pressure for resistance. So it is very important that they undergo full quarantine before they integrate into the flock. Bringing a ram home and putting it straight out with ewes is a high risk strategy.”
“Quarantine should be regarded as an investment in the flock,” says Ms Stubbings, “even if it is just ‘a few rams’ the proper procedure must be followed. And when buying in replacements, farmers are not going to know the impact of buying in resistant worms in the short term, possibly not for years. So it can never be regarded as being expensive to spend a bit of money on these few animals – even though they are only small proportion of the flock – because farmers are protecting the rest.”
Picture: Mike Glover
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