Mycoplasma in poultry is not
a new disease. There is mention in the old books of similar
symptoms from about 100 years ago but it has generally been called
roup or a common cold. Treatment tended to be by culling
The disease acquired the name mycoplasma once the causative
organism had been discovered. Mainly the respiratory system in
poultry is affected and the disease may be becoming more common,
spreading with increased travelling of stock, more people keeping
chickens and mixing them from different sources. The incubation
period before clinical signs appear can be as little as a few days
- it is very infectious. It appears to thrive in the bird when
other pathogens are present, such as E. coli or infectious
bronchitis (IB is certainly now more common in free-range flocks)
or if the birds are stressed or debilitated. Debilitating factors
include nutritional deficiency, excessive environmental ammonia and
dust and stressors such as changes in the pecking order or
Fig 1: Normal turkey head (note quite sunken
appearance): Bourbon Red female
Fig 2: Normal chicken head:
Causes and clinical signs
The organism is neither a bacterium nor a virus in size, but
part way between, having no cell wall but with a plasma membrane.
Four out of the known 17 species of mycoplasma are pathogenic in
Mycoplasma gallisepticum: signs can include foamy eyes,
sneezing, nasal discharge, swollen eyelids and sinuses, reduced egg
production and gasping in chickens, turkeys and pheasants, swollen
sinuses in waterfowl. This one is the main culprit in backyard
Mycoplasma synoviae: signs include swollen and hot
joints in chickens and turkeys and/or respiratory signs as above,
or thin, deformed shells at the broad (apical) end of the egg.
Mycoplasma meleagridis: signs include poor growth in
turkey poults and lowered hatchability in turkey breeders.
Mycoplasma iowae: signs included reduced hatchability
in turkey breeders, twisted legs in turkey poults.
When nasal discharge is evident, feathers become stained with
this as the bird tries to clean its eyes and nostrils. There is a
particular sweet smell associated with this discharge which to the
sensitive nose is immediately apparent when entering a hen
Fig 3: Nebraskan Spotted Turkey with
Mycoplasma. Note swollen sinus (arrowed)
Nasal discharge and cool
temperatures are protective of the organism so any sneezing will
deposit droplets which will remain infective for several days.
Transmission is also through the egg, plus carried on the clothes
and hands of people tending the birds.
Reduced egg production and
reduced weight gain in chickens, turkeys, waterfowl and
Diagnosis is on clinical
signs, see above.
Swollen hock (Fig 4) and Apical eggshell deformities (Fig
5) both due to Mycoplasma synoviae
Fig 6 White Orpington with
severely swollen sinuses and nasal discharge
Antibiotic treatment will not
completely cure the disease but will reduce the incidence to a
tolerably low level. Tylan Soluble is licensed for the treatment of
mycoplasma and is probably the best treatment. Baytril Oral should
not be used in laying hens as it will take them out of the food
chain. Tylan Soluble is effective in young stock but seems to be
less effective in older stock unless given at the acute (early)
stage of the disease. If still showing signs after treatment the
bird must be culled as the organism will be too deeply entrenched
within the airsacs and hollow bones to be removed, the bird
remaining a carrier which will infect others. (Denagard is
sometimes prescribed for chickens: this drug combined with the
coccidiostat in a grower ration becomes fatal, so only use it in
adults on a layer ration).
- Keep stressors to a minimum or if a known stressor such as a
show is imminent, give vitamin supplementation. There are several
useful products on the market which contain probiotics and/or
vitamins, administered in the water.
- Use a suitable disinfectant for both huts and equipment such as
Virkon or F10.
- Keep dust and ammonia levels low by having (vermin-proof)
ventilation on two sides of the hut at the top and never closing it
off. Ammonia paralyses the small hairs (cilia) which act like an
escalator to move normal mucus up the trachea before being
- Feed high quality commercial food for the stage of growth and
the species of bird.
- Monitor weather changes and take steps to minimise any
- When attending to the stock, begin with the youngest at the
start of the day (i.e. with clean clothes).
- Either quarantine new stock for 2-3 weeks or treat with Tylan
Soluble as soon as the birds are obtained if there has been
mycoplasma in your flock.
- Do not buy from auctions.
- If adult stock are kept symptom-free the risk of passing
mycoplasma on through the egg is reduced.
- If young stock happen to be exposed to a mild bout of
mycoplasma they will acquire a certain amount of immunity as long
as there are no other pathogens (such as E.coli)
- Cider vinegar (10ml:500ml, plastic drinker only to avoid zinc
toxicity) helps strengthen the immune system and keeps drinkers
cleaner. Use one week a month, more often if diseases are
There is a mycoplasma vaccine marketed by MSD but it is
recommended not to use it in breeding chickens. This appears to be
because the manufacturers do not know how long the vaccine is
With vigilance, mycoplasma can be kept at a low level in
backyard flocks thus increasing the welfare of the birds.