Mycoplasma Synoviae

Infectious Synovitis is a bacterial disease affecting chickens caused by Mycoplasma Synoviae (MS). It causes a wide variety of damage to joints, tendons, tissues, organs and the respiratory system. Historically it was seen as a disease which affected the synovial membrane of joints and tendons, but is now becoming more common in multi-age flocks presenting as an upper respiratory tract illness. Birds can be infected and appear healthy until stressed, which then triggers systemic symptoms.

Symptoms

Lethargy, depression
Decreased appetite
Ruffled feathers
Stunted growth
Green poop
Pale or bluish comb
Breast blisters
Decreased egg production
Poor egg quality (thinning at the wide end)
Swollen, red and warm hocks, shanks and feet
Fluid retention in hock joints
Difficulty walking
Mild tracheitis, sinusitis or airsacculitis (often seen in conjunction with Newcastle Disease or Infectious Bronchitis)

MS Swollen Feet & Joints (Credit: AECA-WPSA)

MS Poor Egg Shell Quality (Credit: NADIS)

Transmission

Can be spread by chickens, turkeys, wild birds or rodents
Spreads vertically from hens to chicks (via egg) and between birds of all ages within a flock
Direct spread through poop, aerosolized droplets between birds to the eyes or upper respiratory tract
Indirect spread between flocks via fomites (shoes, clothes, equipment)
MS remains infectious in the environment for several days
Incubation period 11- 21 days
Risk factors include stress and pre-existing viral respiratory infections
Seen as a complication of airsacculitis in co-infection with Newcastle disease or Infectious Bronchitis.
High infection, but low death, rates

Treatment

Injectable forms of antibiotics such as tylosin, erythromycin, spectinomycin or chlortectracycline are more effective than those administered in drinking water or feed.
Antibiotics will decrease symptoms, cut recovery times and prevent new transmissions, but are not a cure. All infected birds (even those who are asymptomatic) are considered carriers for life.
Chronically infected chickens are more vulnerable to contracting other pathogens like Newcastle Disease, Infectious Bronchitis or other bacterial infections.

Prevention

Although MS is less common than its cousin Mycoplasma Gallisepticum the prevention strategies are the same:

Purchase birds from a known MS-free flock (NPIP in the USA)
Practice all-in, all out flock management
Adhere to strict biosecurity
Minimize stress
Boost your flocks’ immunity with a balanced feed
Quarantine new birds
Minimize contact with wild birds and rodents (keep feed inside the coop, pick up dropped feed)
Vaccines are not widely available