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Avian Mycoplasmosis

Other Names: Mycoplasmosis

Avian mycoplasmosis is the collective term for clinical disease caused by Mycoplasma. M. gallisepticum and M. synoviae are the two most important Mycoplasma species which affect chickens and other poultry.
  • M. gallisepticum: Can cause Chronic Respiratory Disease (CRD) in chickens and infectious sinusitis in turkeys. It is commonly found in backyard and free-range flocks worldwide.
  • M. synoviae: Is usually associated with subclinical infections, largely confined to the air sacs. When stressed, the infection can become systemic, affecting the synovial membrane of joints and tendons, causing acute and chronic 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
  • Lab tests

Reported Cases

  • Case 1: Mycoplasmosis in a Duck A disease associated with central nervous system signs was observed in two duck flocks, each consisting of 6000 three-week-old ducklings, a week after their arrival at the receiving farms. The clinical signs included leg weakness, dyspnoea, diarrhea, and in many cases disturbance of equilibrium, retrograde movement, torticollis and twisting of the neck. Pathological and histopathological examinations revealed lymphoihistiocytic meningitis and cerebroventriculitis, airsacculitis with moderate amounts of fibrinous exudate, bronchitis associated with formation of lymphoid follicles, focal or interstitial pneumonia, in some cases with fibrinous serositis, interstitial catarrh and splenomegaly. Large numbers of mycoplasmas were seen by electron microscopy and were isolated from the affected meninges and pericardium. Ref

  • Case 2: Chondrodystrophy in a Turkey In September 1989, 17-day-old turkey poults were submitted to Iowa State University because of leg weakness and dehydration. These birds were commercial large white toms from a flock of 23,214. Lesions observed at necropsy included chondrodystrophy of the hock joints, clear fluid in hock joint spaces, valgus deformities and shortening of the tarsometatarsal bones, and curled toes. Mycoplasma iowae was isolated and identified from swabs of the air sac, cloaca, hock joint, and large intestine. Approximately 1.4% of the flock was culled between 2 and 8 weeks of age because of leg problems. M. iowae infection did not severely affect overall flock performance. Eighty-seven percent of the flock was marketed at 18 weeks of age with an average per turkey weight of 29.5 pounds. Ref

  • Case 3: Mycoplasmosis in a Partridges Clinical signs including respiratory and intestinal disorder were seen in birds of all ages but mainly in those kept housed during rearing. Mortality rates averaged over 20% during the year. Treatment with antibiotics and antiparasitic drugs produced only a transient improvement in condition. The gross pathology findings included poor body growth, lack of development of the breast muscles, abnormalities in the keel development, and bone fragility. Some birds showed infraorbital sinusitis with serous or fibrinous exudates and catarrhal tracheitis, while others presented serofibrinous airsacculitis and splenomegaly. Laboratory investigations revealed pure cultures of M. iowae in the gut as well as sinus and air sacs. While other organisms such as coccidia, Trichomonas, Escherichia coli, Clostridium perfringens, and Aspergillus spp. were detected, the similarity of the disease with that seen in turkeys infected with M. iowae strongly suggests that this mycoplasma may be the primary pathogen here. The presence of M. iowae in game birds commonly released into the wild could have serious implications particularly in areas where industrial poultry farms are concentrated. Ref

  • Case 4: Mycoplasmosis in a Turkey Two 5-week-old bronze turkeys were submitted with crooked necks that could not be straightened. Both birds were serologically and culturally positive for Mycoplasma meleagridis (MM). Histologically, there were lymphoid follicles in the cranial thoracic and cervicoclavicular air sacs, and inflammatory changes in the cartilage of some cervical vertebrae. This appeared to be a case of MM-associated wry necks. Ref

  • Case 5: Mycoplasmosis in a Falcon A wild, 3-wk-old saker falcon nestling showing uncoordinated movements and a perosis type tarsometatarsus deformity was found abandoned; it was euthanized a week later on 29 May 1997 after an unsuccessful attempt to rehabilitate it. Gross pathological findings included congestion of parenchymal organs and a lateral bowing of the left tarsometatarsal bone. Histopathology revealed initial interstitial hepatitis, focal catarrhal pneumonia, and dyschondroplasia in the epiphysis of the left tarsometatarsus. Mycoplasmas were isolated from the lungs, trachea, bone marrow and brain. A polymerase chain reaction (PCR) assay was performed for the detection of the mycoplasmal 16S rRNA gene. The resulting 262 base pair PCR product was sequenced and compared to the available mycoplasmal sequences but no identical corresponding sequences were found. However, 98% similarity was found to the Mycoplasma buteonis 16S rRNA and the isolate also was positive by immunoblotting against reference sera to the same species. Ref

  • Case 6: Salpingitis in a Geese An outbreak of disease in a White Rhine laying goose flock was characterized by increased water uptake, increased mortality, production of eggs with abnormal shells, a 25% drop in egg production and 40% embryo mortality. Affected dead or sacrificed birds had sero-fibrinogranulocytic peritonitis and salpingitis, infiltration of the lamina propria in the uterus and heterophil granulocytes in the isthmus and magnum of the oviduct. Mycoplasmas, mainly identified as Mycoplasma sp. strain 1220, were isolated from the airsac, liver, ovary, magnum and peritoneum of some affected geese. Strain 1220 was originally isolated from a Hungarian gander with phallus inflammation and, according to detailed biochemical and serological examinations, it is expected to represent a new avian species within the genus Mycoplasma. Ref

  • Case 7: Mycoplasmosis in a Chickens Mycoplasma synoviae (MS) infection was diagnosed in a flock of 113-day-old, brown feathered, meat type, chickens. Ten live birds were submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in Center, TX with a clinical history of respiratory problems and increased mortality. At the necropsy examination, the birds had tracheas with reddened mucosa and excess mucus in the lumens, opaque and thickened pericardia, thickened thoracic air sacs with large accumulations of yellowish caseous exudate, and bloody/gelatinous material accumulated over the keel bone. PCR testing yielded positive results for MS. Ref

  • Case 8: Eggshell apex abnormalities in a Chickens Eggshell abnormalities were seen in the apex of eggs in two of three flocks of multi-age, HyLine layer chickens housed on a farm in Northern Italy. Approximately 1.3% to 1.8% of eggs in one flock were affected, amounting to 300–400 eggs per day; the abnormalities resulted in a great deal of breakage and spoilage of healthy eggs. The mean weight of eggs was also reduced. Egg abnormalities in a second flock were less severe. Mycoplasma synoviae was detected in birds from both of the affected flocks by serologic, cultural, and molecular techniques, but not in a third, adjacent flock where no eggshell abnormalities were seen. Treatment with tylosin, administered in the drinking water for 5 days, resulted in an immediate improvement of eggshell quality and egg weight. There was no evidence of infectious bronchitis virus in the flocks. Ref


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
Baicalin (Scutellaria baicalensis) extract450 mg/kg of dietJ Bao et al., 2021; Z Wu et al., 2019, 2020; M Zou., et al. 2021; M Ishfaq et al., 2019, 2021; J Li et al 2019; Y Wang et al. 2022; F Yang et al., 2020; Y Zhou et al., 2019; B Yin et al., 2021; M Bao et al., 2022; Z Hu et al., 2022
ProbioticsWhen added to the diet of chickens infected with Mycoplasma, it alleviated lung inflammation injury caused by the infection and increased their defense against Escherichia coli by improved gut microbiota composition.J Wang et al., 2021



  • Cover feed and water to prevent contamination from wild birds
  • Quarantine new birds for 30 days before adding them to the flock.
  • Minimize stress



Scientific References

Good Overviews

Risk Factors

  • High populations of wild birds on the premises.
  • Males and young chickens are affected more severely than females and adult birds.
  • Stress