A Comprehensive Review of Ovine Progressive Pneumonia in Sheep

Ovine Progressive Pneumonia (OPP), also known as Maedi-Visna, is a chronic and infectious disease that afflicts sheep worldwide. This article delves into the many aspects of OPP, covering its causes, symptoms, treatment, and preventive measures.

Overview of Ovine Progressive Pneumonia

OPP is a slow-acting disease caused by a lentivirus, which is a subtype of the retrovirus family. The lentivirus responsible for OPP is called the Ovine Progressive Pneumonia Virus (OPPV). The disease primarily targets the respiratory and nervous systems, along with the joints and the mammary glands.

Symptoms and Diagnosis of OPP

OPP symptoms vary based on the system it attacks. Here are the primary symptoms associated with each system:

Respiratory System:

  • Persistent coughing
  • Increased respiratory rate
  • Difficulty in breathing

Nervous System:

  • Weakness in the hind legs
  • Weight loss and poor condition
  • Behavioral changes and reduced productivity


  • Arthritis and lameness
  • Swollen carpal joints

Mammary Glands:

  • Hard udders and decreased milk production

OPP diagnosis typically involves serologic testing, where a blood sample is tested for the presence of antibodies against OPPV. Polymerase chain reaction (PCR) tests can also be used to detect viral genetic material.

Treatment and Management of OPP

There is, unfortunately, no cure for OPP. The focus is generally on managing the symptoms and preventing further spread of the disease. Sheep affected by OPP should be isolated to minimize the risk of transmission.

However, there are management practices that can help control the disease:

  • Regular health checks
  • Strict quarantine protocols for new animals
  • Removal of OPP-positive sheep from the flock

Prevention of OPP

Preventing OPP is crucial to avoid economic loss and maintain the health and productivity of your flock. The following are some measures that can be implemented:

  • Regular Testing: Regular OPP testing of your flock helps detect and manage the disease early.
  • Isolation: Isolate new or suspect animals until they have been tested and cleared.
  • Culling: If OPP is detected in your flock, cull the affected sheep to prevent the spread to healthy ones.
  • Clean Feeding Practices: Colostrum and milk from infected ewes can spread OPP. Use pasteurized colostrum or milk replacers for lambs.

OPP is a serious concern for sheep farmers due to its chronic nature and potential for economic losses. While there is no cure, understanding the disease, its symptoms, and implementing sound preventive measures can help mitigate its impact. Regular testing, isolation, culling, and clean feeding practices are key in preventing the spread of OPP. By taking these steps, you can maintain a healthy and productive flock.

“The only good system is a sound system.” – Bill Mollison

As sheep farmers or shepherds, it’s our responsibility to adopt sound systems to prevent diseases like OPP. The health and productivity of our flock rely on our continuous efforts and the best practices we put in place. Despite the challenges OPP presents, with careful management and a proactive approach, we can protect our sheep from this debilitating disease.

Remember: Regular health checks and preventive measures can significantly reduce the risk of OPP in your flock.


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