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Infectious Synovitis (Mycoplasma synoviae / MS) in Poultry

Guide covering Mycoplasma synoviae etiology, joint exudate, breast blisters, lameness, MS-H vaccine, and Tylosin therapy.

Scientific Overview

Infectious Synovitis is an acute-to-chronic infectious disease of chickens and turkeys caused by Mycoplasma synoviae (MS). It primarily targets synovial membranes of joint capsules, tendon sheaths, and bursa, leading to swollen hock joints, breast blisters, severe lameness, and growth retardation.

Etiology & Transmission of Mycoplasma synoviae

Mycoplasma synoviae (MS) is defined as a cell-wall-less bacterium causing synovitis and subclinical upper respiratory tract infection.

Transmission occurs vertically through breeder eggs and horizontally via respiratory droplets. MS can remain persistent in flocks for the duration of their life cycle.

Pathology: Swollen Hock Joints & Tendon Exudate

Clinical signs and lesions include:

  • Lameness & Hock Swelling: Birds wobble on legs with hot, swollen hock joints and footpads.
  • Viscid Synovial Exudate: Joint cavities contain cream-colored to honey-like viscous fluid that hardens into caseous pus in chronic stages.
  • Sternal Bursitis (Breast Blisters): Prominent fluid-filled blisters over the keel bone due to birds resting on litter.

Control: MS-H Live Eye-Drop Vaccine & Antibiotics

Prevent MS by acquiring MS-free breeder stock and administering live MS-H vaccine via eye drop at 5–6 weeks of age. In active outbreaks, administer water medication with Tylosin, Tiamulin, or Chlortetracycline.

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Infectious Synovitis (Mycoplasma synoviae / MS) in Poultry — Frequently Asked Questions

What is the difference between MG and MS in chickens? expand_more
Mycoplasma gallisepticum (MG) primarily causes respiratory airsacculitis and sinusitis, while Mycoplasma synoviae (MS) targets joint synovial membranes, causing lameness and swollen hocks.
Can Mycoplasma synoviae be passed through eggs? expand_more
Yes, MS is transmitted vertically from infected breeder hens into hatching eggs, making MS-clean breeder replacement essential.
What antibiotics treat Infectious Synovitis? expand_more
Macrolides and pleuromutilins like Tylosin, Tiamulin, and Chlortetracycline are effective at reducing clinical joint swelling.
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Related Pathologies & Differential Diagnosis

Differential diagnostic screening: Cross-reference clinical lesions and flock symptoms against these closely associated avian pathologies:

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Chicken foot and hock joint exhibiting severe caseous exudative synovitis, interdigital swelling, and arthritis biotech Clinical Pathology
Clinical Pathology: Infectious Synovitis (Mycoplasma synoviae) Interdigital Arthritis • Photo: Dr. Lucien Mahin, DVM • CC BY-SA 4.0

Related Calculators

Scientific Literature

  • WOAH Terrestrial Manual (Mycoplasma synoviae).
  • Diseases of Poultry, 14th Edition (David E. Swayne et al., 2020).