Contagious Agalactia in Sheep and Goats: A Welfare-Significant Flock Disease

Contagious agalactia is a mycoplasmal disease causing mastitis, arthritis, and keratoconjunctivitis in small ruminants, with significant welfare impacts across affected flocks.

Key Facts

Contagious agalactia (CA) is caused primarily by Mycoplasma agalactiae in sheep, and by M. mycoides subsp. capri and other mycoplasmas in goats.
The name refers to the most dramatic sign — loss of milk production (agalactia) — but the disease also causes joint inflammation (arthritis) and eye inflammation (keratoconjunctivitis).
CA is endemic in Mediterranean countries, the Middle East, Central Asia, and parts of Africa; it causes major economic losses in dairy small ruminant production.
Transmission occurs through milk, nasal secretions, urine, and feces; introduction of carrier animals without quarantine is the most common route of herd entry.
Affected animals experience painful swollen joints, difficulty walking, reduced vision, and mastitis causing teat pain and udder damage.
Antibiotic treatment with tetracyclines or fluoroquinolones can reduce severity but rarely eliminates the organism; mycoplasmas lack cell walls making many antibiotics ineffective.
Vaccination is available and is the primary control strategy in endemic areas, though vaccines provide partial rather than complete protection.

Welfare Considerations

Contagious agalactia causes multisystem welfare compromise that can persist for months in affected individuals. Arthritis causes chronic joint pain that limits movement and normal behavior; affected animals may be reluctant to walk, graze normally, or compete for resources. Keratoconjunctivitis causes eye pain, photophobia, and impaired vision, reducing the ability to navigate safely and detect threats. Mastitis causes teat and udder pain and prevents normal suckling — lambs and kids of affected ewes and does face starvation if not supplemented. The chronic, recurring nature of the disease in endemic flocks means animals may experience repeated painful episodes across their productive lives. Control programs that combine vaccination, biosecurity, and early case identification and isolation can dramatically reduce the welfare burden in affected flocks.

What You Can Do

Support biosecurity programs that prevent introduction of CA to naive flocks through quarantine of new animals.
Advocate for vaccination programs in CA-endemic regions as the primary welfare and production protection strategy.
Encourage early veterinary involvement when multiple animals in a flock show mastitis, lameness, or eye disease simultaneously.
Support research into more effective mycoplasma vaccines and treatment protocols.
Learn about welfare monitoring in small ruminant flocks — CA is one of several diseases causing significant but sometimes underrecognized suffering.