Quarantine: why and how long?
By Megan Fergusson – Veterinary Investigation Officer
With sheep sales underway and many more on the horizon, now is an ideal time to review your quarantine procedures to avoid bringing in more than you bargained for. Buying in any stock can pose a significant health risk to your flock. If done well, quarantine can remove or reduce the risk posed by incoming animals.
Where and for How Long?
Incoming sheep should be housed or put on pasture that will not be grazed by your own flock. Some diseases, such as sheep scab, can be transmitted through handling facilities and trailers, so a good disinfection protocol should be used between batches of sheep.
The length of quarantine time will depend on the diseases being screened for or treatments required. A minimum of twenty-one to twenty-eight days is commonly suggested. Whole groups should be quarantined until all testing and appropriate treatment is complete.
Parasites
Anthelmintic resistance is one of the biggest threats to sheep production. Incoming sheep have great potential to introduce both resistant worms and new species of worm, such as haemonchus, to your farm. Incoming sheep should be treated to eliminate any resistant worms, and it is essential that following treatment, any worms that are passed are not passed onto areas that will be grazed by the existing flock. Hence, the rationale behind housing or quarantine paddocks for at least 48 hours post-treatment. The quarantine worming strategy to be used will vary on each farm. Discuss with your vet the best approach for your farm. The SCOPS website is a great resource for quarantine worming protocols.
Parasite quarantine procedures should also take into account the risk of sheep scab. Not all infected animals will appear itchy, and previously non-infected animals could become infected after moving through a market, handling pens, or sharing transport. The most effective way to ensure scab is not introduced to your flock is to dip on arrival. Blood sampling can also be used 14 days after arrival to assess for exposure to sheep scab; the group should remain in quarantine until results are back.
Iceberg Diseases
The ‘Iceberg diseases’ include Border Disease (BDV), Maedi-Visna (MV), Johne’s disease, Ovine Pulmonary Adenocarcinoma (OPA), and Caseous Lymphadenitis (CLA). All of these conditions can cause long-term production losses in your flock. Depending on the diseases already present in your flock, you may want to screen some or all incoming animals. There are blood tests available for BDV, MV, CLA, and Johne’s disease, and some vets can screen for OPA using ultrasound. Talk to your vet about the best testing strategy for you.
Infectious Lameness
Footrot and Contagious Ovine Digital Dermatitis (CODD) cause lameness and can be challenging to manage. Any sheep which become lame during the quarantine period should be examined. If footrot or CODD is identified, then sheep should be treated, and the lameness resolved prior to the sheep entering the flock. You may want to consider whether you want to add animals which are predisposed to getting footrot/CODD to the flock.
Vector-Borne Diseases
Although Schmallenberg virus (SBV) and bluetongue virus (BTV) are spread by midges, it is theoretically possible for either of these viruses to travel in a sheep that has recently been infected. Transmission to other sheep thereafter would mainly rely on the involvement of midges. If bringing in sheep from high-risk areas, minimizing exposure to midges for at least two weeks following arrival is advised. Blood sampling can be done for both diseases to assess for exposure.
While these tests and treatments can seem expensive, the cost of lost production, disease treatment, or eradication if these parasites or diseases infect your flock will be significantly more. Prevention is always better than cure.
Posted by SRUC Veterinary Services on 13/09/2024
