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Flip Over Disease in Broilers

By Alberta Agriculture

Also known as Acute Death Syndrome

Flip-over disease, or acute death syndrome, can cause a serious mortality rate in broiler chickens.

Flip-over disease usually affects the larger, and rapidly growing, broilers that are between 2 and 12 weeks old. Most cases occur when the birds are between 3 and 5 weeks old. Although the percentage of birds affected is usually low, perhaps about one percent, in some instances it may be as high as 5 percent. The condition can also affect small farm flocks.

Small farm broiler flocks may be affected by the disease, but it is not usually a problem in these situations because the rations are often not conducive to rapid growth.


Birds that succumb to flip-over disease are often found dead on their stomachs with their legs stretched out behind them and their necks extended forward. Occasionally, a dead bird is fount on its back. There is rarely any sign of sickness prior to such deaths, but some people have observed a bird, which appeared to be perfectly normal, suddenly squawk, and make a small jump into the air and land on its back. The wings flutter, there are some convulsive movements and the bird is dead.


The cause of flip-over disease is still obscure. Heart attacks and enterotoxemia have both been suggested as causes, but neither theory has been substantiated.


Decreasing the light intensity in commercial broiler barns, thereby slowing down the activity of the birds, appears to reduce the incidence of flip-over disease. Inhibiting the growth of the birds has also been reported to reduce the problem, but this is obviously not a practical approach. Apart from keeping the birds as calm as possible, there is very little that can be done to prevent flip-over in flock of broilers, or to prevent it from occurring in other flocks, until the cause of the condition has been determined.