Egg yolk peritonitis
Egg yolk peritonitis is commonly diagnosed in laying hens when yolk from a developing egg or an incompletely shelled or ruptured egg is deposited within the body cavity (the coelom).
Normally, the developing egg passes from the bird’s single ovary (generally on the left side of the body) into the single tube-like oviduct (salpinx) and then out of the body, through the vent, as a fully shelled egg.
The yolk material that is released into the coelomic cavity then causes inflammation of the peritoneum (the thin layer of tissue lining the coelom and internal organs) and typically the development of fluid within the coelom.
The yolk material can become infected with bacteria (most commonly E. coli) that can then spread into the bloodstream, causing a secondary, potentially life-threatening infection in critical organs such as the kidneys, liver, and heart.
Hens with egg yolk peritonitis will stop laying eggs or lay only soft-shelled, thin-shelled, or misshapen eggs. They may be less active, choosing to sit more in the nest box rather than to walk around, and they may eat less than normal. Affected hens may have visibly distended abdomens due to the presence of fluid and may have difficulty breathing from the pressure of the fluid on their respiratory tract
Egg yolk peritonitis may occur simply from a single egg not forming properly or may develop secondary to other underlying reproductive diseases including inflammation of the oviduct (salpingitis), impaction of the oviduct with multiple abnormally formed eggs, ovarian cysts or cancer, or twist of the oviduct preventing normal passage of eggs through it.
If your chicken is showing signs suggestive of egg yolk peritonitis, she should be examined by a veterinarian familiar with chickens as soon as possible. Your veterinarian will perform a complete physical examination and may palpate (feel with fingertips) fluid or soft-shelled eggs in the coelom. Your veterinarian also may note that you bird is breathing quickly or with increased effort.
Typically, the veterinarian will perform blood tests, including a complete blood count (CBC), that may show an elevated white blood cell count, indicating inflammation or infection. The veterinarian also may perform coelomocentesis in which he or she inserts a small needle into the bird’s coelom, typically just below the keel (breast bone), to draw off fluid present in the abdomen. This fluid is usually submitted to a referral laboratory for microscopic analysis and culture to determine whether bacteria are present and if so, which antibiotics will be most effective for treating the infection.
The veterinarian also may take radiographs (X-rays) or perform an ultrasonographic examination to further assess the inside of your bird’s coelom and to confirm the presence of fluid and/or unshelled or partially shelled eggs.
Mild cases of egg yolk peritonitis, in which there is no secondary bacterial infection or underlying reproductive disease, may require only supportive care such as supplemental hand feeding and anti-inflammatory medication.
With more advanced cases in which infection is present, your veterinarian may prescribe oral or injectable antibiotics. More aggressive supportive care may be required, such as hospitalization for fluids injected subcutaneously (under the skin) or intravenously (in a vein), oxygen therapy, and repeated drainage of coelomic fluid. In the most advanced cases, surgery (called salpingohysterectomy) to remove the offending egg(s) and oviduct may be necessary.
Many avian veterinarians treating egg yolk peritonitis also will administer a hormone, either through injection or as a slow release implant under the skin. This will temporarily prevent further egg laying that would worsen the hen’s already compromised condition.
While egg yolk peritonitis may be life-threatening, with proper treatment, birds with this condition can be treated successfully.