Maedi-visna is debilitating viral disease that can undermine the economic viability of a sheep flock.

The name Maedi-Visna is an Icelandic description of the two major forms of the disease (Maedi=progressive pneumonia and Visna=wasting). Although it is ultimately fatal, most of the economic loss attributed to this disease is due to decreased milk production; lowered weaning weights; increased incidence of severe arthritis and wasting; higher than average number of respiratory infections; and decreased ewe fertility. In one study, it was found that 66% of healthy appearing, Maedi-Visna positive ewes had udder lesions and their lambs had lower than average weaning weights. The disease is common in many sheep producing countries, and 70% of flocks tested in Ontario in the late 1980's had at least one positive animal. There is no cure or treatment for the disease, however, there is a reliable blood test that can identify infected animals. 

The Ontario Maedi-Visna Flock Status Program (OMVFSP)

The OMVFSP is a voluntary program to enable sheep producers to determine the disease status of their flocks with respect to Maedi Visna infection, and to eradicate this infection through a program of biosecurity, serological testing of sheep and subsequent removal of postive animals from the flock.

To enroll in the program, the producer must be willing to follow the rules of the program, permanently and uniquely identify all sheep in the flock, and follow specific biosecurity requirements.

Testing your flock

  • Blood is collected by your flock veterinarian and samples are sent to the Animal Health Lab at the University of Guelph at a cost of $11.50 per sample.
  • Results are sent to Ontario Sheep Farmers (OSF), and OSF then informs you and your vet of your test results.

Learn more about the OMVFSP program

OMVFSP enrollment form

Maedi-Visna Protocols

List of producers enrolled in Ontario Maedi Visna Flock Status Program

Additional Resources 

  • Maedi Visna and what it means for your flock - By Dr. Paula Menzies click here
  • The National Sheep Producer Biosecurity Planning Guide click here

For more information or to enroll in the program

Contact the Ontario Sheep Farmers office
P: 519.836.0043