A Guide to Eradicating Lentiviruses (OPP and CAE) from Your Flock

by Dr. Hannah Stokley, DVM

Ovine Progressive Pneumonia (OPP) and Caprine Arthritis and Encephalitis (CAE) are challenging lentiviruses affecting sheep and goats worldwide. These diseases can lead to chronic respiratory, mammary, joint, neurologic, and wasting conditions in infected animals. Infected flocks can cause significant economic losses for farmers. Fortunately, with a systematic approach and diligent management, it is possible to eradicate lentiviruses from a flock. This guide provides practical steps and strategies for achieving this goal.

Step-by-Step Eradication Plan

1. Segregate your flock into two groups

• Parent Group: Animals that are from your original flock that are 12 months of age or older regardless of OPP/CAE status.

• OPP/CAE Free Replacements Group- offspring from the parent flock that have been found to be 100% OPP/CAE negative post weaning with two sets of testing 3 months apart.

Never allow the two groups to come into contact. Do not allow for shared fence lines, waterers, or feeders. When working with your animals always work with the OPP/CAE free replacement group first. The pathogen can persist in the environment but is killed by most common disinfectants. Be sure to disinfect any working facilities and fomites when moving between groups.

2. Cull any OPP/CAE positive animals that are a year of age or older

This eradication strategy is designed to transform an OPP/CAE positive flock to an OPP/CAE free flock without the necessity of culling all positive animals. By culling all positive animals you will reach an OPP/CAE free herd in a more timely manner and it is highly recommended.

3. Forming the OPP/CAE free replacement group

• Lambs and kids from infected dams should be orphaned: lambs and kids from infected dams should not consume any of the infected dams colostrum or milk and should instead be grafted to an OPP/CAE negative dam or fed milk replacer or milk from a negative sheep/goat until weaned.

• Wean at 6-8 weeks of age- wean lambs from the parent flock early and segregate them to their own group away from the parent group.

• Test all of the segregated lambs and kids starting 3 months after weaning- move any positive lambs or kids to a strict solitary quarantine with solid panel confinement and retest in 6 weeks. Cull any animals that test positive twice at the 6 week retest. If they are negative for two tests second time then return them to the negative parent group

• Test the replacement group every 3 months- test the replacement group every 3 months, removing any positive animals as stated above, until you have two consecutive 100% negative test results.

  
  

4. Monitoring

• Annual testing- test each group annually, ideally prior to the breeding season, cull any positive animals

• Monitor Health: Keep a close watch on flock health and immediately investigate any signs of illness.

5. Adding animals to the OPP/CAE free group

• Lambs and kids from subsequent breedings of the parent group: manage the lambs and kids as stated above by weaning at 6-8 weeks of age, segregating them into their own group and only adding them to the OPP/CAE free replacements group when they have had two consecutive negative tests 3 months apart

• Lambs and kids from the OPP/CAE free replacements: lambs and kids can stay with their dams in the OPP/CAE free replacement group. They should be tested at six months of age, one year of age, and then annually. If any of the lambs or kids test positive, they should be removed promptly, placed in strict solitary quarantine, retested in 6 weeks, and the whole OPP/CAE free replacement group should be tested.

• Animals purchased off farm or animals that have traveled off of the farm- animals over a year of age, that have been quarantined for 60 days, and have had two consecutive negative OPP/CAE test results 6 weeks apart can be added to the OPP/CAE free replacement group

6. Manage Environmental Contamination

The virus can survive in the environment, so it’s essential to manage potential sources of contamination:

• Clean Facilities: Regularly clean and disinfect housing, feed areas, and any equipment that may come into contact with the animals. The virus is effectively killed by most common disinfectants.

• Manage Waste: Properly manage manure and bedding to prevent contamination.

Long-Term Strategies for Success

• Maintain Records: Keep detailed records of testing, culling, and health management to track progress and make informed decisions.

• Engage with Veterinarians: Work closely with veterinarians to stay updated on the latest research and control methods.

Eradicating Ovine Progressive Pneumonia and Caprine Arthritis and Encephalitis from a flock requires a comprehensive and persistent approach. By implementing stringent biosecurity measures, conducting regular testing, culling infected animals, and maintaining rigorous management practices, you can significantly reduce, and eventually eliminate, the impact of OPP and CAE on your flock. While the process can be demanding, the long-term benefits of a healthy, disease-free flock are well worth the effort.

You can learn more specifically about OPP from Dr. Michelle Arnold's Ovine progressive pneumonia (OPP) blog post.

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Dr. Hannah Stokley is a recent graduate of Auburn University's College of Veterinary Medicine and the owner of Bluegrass Mobile Veterinary Services. Her mobile veterinary practice serves both large and small animals across a wide range of locations in Kentucky. Dr. Stokley hopes to be a valuable asset to her community and strives to make veterinary care more accessible.