Mycoplasma arthritis

Mycoplasma hyosynoviae and M. hyorhinis are present in most farms and cause arthritis in swine.

Alternative names: Mycoplasma hyosynoviae, Mycoplasma hyorhinis


Most farms are infected but not all of them show clinical signs. Mycoplasma hyosynoviae and M. hyorhinis live in the upper respiratory tract without causing clinical signs and are transmitted through the respiratory route. They invade joints and tendon sheaths of susceptible animals producing inflammation and lameness.

Mycoplasma hyorhinis clinically tends to occur in swine from 3 to 10 weeks old and Mycoplasma hyosynoviae is present in pigs of more than 3 months. M. hyorhinis, besides causing arthritis can also cause polyserositis and pneumonia.


All ages

  • Lameness.
  • Inflammation of joints, especially hocks.
  • Body temperature may be normal or slightly elevated.
  • Tremor.
  • Polyserositis (M. hyorhinis).
  • Pneumonia (M. hyorhinis).

Causes / Contributing Factors

  • The quality of housing - especially low temperatures and air draughts, which act as triggers.
  • Mixing of animals and fights, such situations cause stress.
  • High density of animals.
  • Poor ventilation.
  • Slippery or rough floors.


  • Serology is not of much help because subclinical infections are common and therefore healthy animals often have antibody titers. However an increase in antibody titer in blood samples taken two weeks apart, along with typical symptoms, suggests the presence of the disease.
  • Necropsy.
  • Sampling of joint fluid in anesthetized live animal.
  • Sampling of lung from pneumonia.
  • Sampling of pleural or pericardial fluid from polyserositis.
  • Culture or PCR testing.
  • Histologic evaluation of joint tissue (synovium).
  • Oral fluids samples are often positive especially for M. hyorhinis.


  • Antibiotics can be used to treat early infections.
  • Strategic use of antibiotics can help minimize transmission and clinical signs but will not eliminate the organism form the herd.

Atlas of pathology

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