by Alberta Algriculture
What is ascites?
Ascites syndrome is a type of congestive heart failure seen mainly in
young rapidly growing meat type chickens. It has become a major concern to
the poultry industry around the world and it is extremely common in Alberta
Ascites is an accumulation of protein rich fluid in the body cavity.
Because of the high protein level, there may be clots of yellow, jelly-like
In birds, the right side of the heart is thin walled and the valve on
this side consists of a flap pushed against the wall of the heart. As well,
lungs of birds are different from those of animals. Bird lungs have very
little ability to expand and the blood capillaries in the lungs are not able
to handle increased blood flow or blood pressure.
When the right heart encounters increased blood pressure in the arteries
of the lungs, it responds to increased workload, as other muscles do, by
getting bigger. If the pressure remains high, the muscle continues to
thicken until the valve no longer is able to completely close. This causes
blood pressure to rise in the veins leading to the heart, especially from
the liver. The result is an increased pressure in the liver with leakage of
blood fluids, without the red blood cells, into the body cavity forming
What causes it?
The genetics of meat birds has changed dramatically in the last ten
years. Today's broilers grow much faster, eating less feed. The growth of
the heart and lungs has not increased in size proportional to the increase
in body weight and breast meat yield. The rapid growth of the bird means
more oxygen demand, requiring more work out of the heart and lungs.
Anything that limits oxygen uptake from the lungs is going to cause the
heart to work harder. Diseases of the lungs and poor ventilation may be
Excess levels of sodium in the water or salt in feed leads to increased
blood pressure in the lungs. Many well waters in Alberta have high levels
of sodium. Levels of sodium over 400 ppm could cause problems in broilers.
High altitudes have long been known to cause heart failure and ascites.
Chilling is a common cause in small flocks. It causes an increased
blood flow through the lungs.
Signs of the disease
Broilers with ascites look bluish because they are not getting enough
oxygen in their blood. They have trouble breathing and often just sit and
pant. They tire out easy and often die on their bellies. When it occurs
within the first week of life, too much salt in feed or water usually is
involved. Because the heart failure takes time to develop, most deaths begin
at about 3 weeks of age.
Birds that die from ascites are quite easy to recognize. If their belly
is opened as in proceeding to clean the bird, a cup or more of fluid or
jellied material will pour out. Sometimes birds with the condition die from
the effects of too much blood and fluid in their lungs before there is any
significant amount of fluid in the body cavity.
Ascites can be controlled by slowing the growth rate of the birds to
reduce oxygen requirements. This can be done by restricting feed, feeding a
mash diet, or using a less dense (lower energy and protein) diet. The other
things causing ascites need to be controlled. If your water has high levels
of sodium, consider using an alternate source of water that is better
quality for the first 3 - 4 weeks. Take care to prevent chilling or
overheating while at the same time maintaining proper ventilation.
As one can see, the cause of ascites is increased blood pressure in the
lungs leading to a failing heart. The things that can lead to increased
pressure and a failing heart are many. There is no one easy solution. Losses
from the condition can be greatly reduced once problem areas are identified