- news, features, articles and disease information for the swine industry

ThePigSite Quick Disease Guide

Use the above box to quickly switch to another disease

Mycoplasma Arthritis

Related Products:
Most herds are infected although not all infected herds show clinical signs. Mycoplasma hyosynoviae lives in the upper respiratory tract without causing clinical signs and is spread by droplet infection. It invades the joints and tendon sheaths of susceptible animals and causes lameness and swelling.

Older sows develop a strong immunity which they pass to their offspring in the colostrum.

Infection takes place sometime after this colostral immunity has worn off, usually between 12 and 30 weeks of age but sometimes gilts do not become infected until introduced to a new herd or in early pregnancy.

It is common in purchased gilts which have been reared in isolated grow-outs, but uncommon in mature sows.

Infection with or without disease takes place in the growing pig from approximately 8 to 30 weeks of age.


  • Clinical signs in the gilt are sudden in onset.
  • Starting with a reluctance to rise.
  • Lameness.
  • Swellings over hock joints visible.
  • Affected pigs are in pain and only stand for short periods.
  • The temperature may be normal or slightly elevated.
  • Shivering.
  • None.
  • Disease rare.
  • Protected by maternal antibodies
Weaners & Growers
  • Reluctance to rise.
  • Trembling.
  • Considerable amount of pain particularly when standing.
  • Only stand for short periods of time.
  • Temperature normal or slightly elevated.
  • Lameness swollen joints.

Causes / Contributing factors

  • The quality of housing - in particular low temperatures and draughts which act as trigger factors.
  • Mixing and fighting.
  • Respiratory spread.
  • High stocking density.
  • Sudden reduction in energy intake producing stress nutritional changes.
  • Poor ventilation.


This is based on clinical signs and the response to therapy. Joint fluid can be aspirated and examined for antibodies and the organism can be isolated.

Serology is not much help because sub-clinical infection is common and so healthy animals often have antibody titres. Rising titres in blood samples taken two weeks apart aid diagnosis.

Post-mortem examination may be necessary to reach a definitive diagnosis.

It must be differentiated from muscle damage, leg weakness, trauma, erysipelas, and Haemophilus parasuis arthritis.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.