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Other Names: Mycoplasmosis

Mycoplasmosis is caused by infection with Mycoplasma spp. Although there are more than twenty species of Mycoplasma which can infect birds, the two most significant pathogens to chickens include M. gallisepticum (MG), and M. synoviae (MS).
  • M. gallisepticum (MG): Causes Chronic Respiratory Disease in chickens. One of the most common causes of respiratory disease in backyard poultry.
  • M. synoviae (MS): Infections may be subclinical or result in respiratory disease or Infectious Synovitis .

Clinical Signs

Nasal/eye discharge
Tracheal rales
Reduced appetite
Weight loss
Reduced egg production
Warm, swollen hocks or footpads


  • History
  • Clinical signs
  • Physical exam
  • Blood test


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Lincomycin/spectinomycinAdministered orally (50 mg/kg q24h), or in drinking water (528 mg/L for 3-7 days)B Speers
TiamulinAdministered orally (25-50 mg/kg, once a day) or in drinking water (0.25 g/L) for 3-5 daysB Speers, A Garmyn et al., K Marx
TilmicosinAdministered orally (30 mg/kg q24h) or in drinking water (100-500 mg/L) for 5 daysB Speers
Tylosin (Tylan)Administered IM (15-30 mg/kg q6-12h),or in drinking water (250-1000 mg/L)B Speers



  • Cover feed and water to prevent contamination from wild birds
  • Quarantine new birds for 30 days before adding them to the flock.
  • Discourage wild birds by taking down bird feeders and bird baths.



Scientific References

Good Overviews

Risk Factors

  • High populations of wild birds on the premises.