Egg Yolk Peritonitis, sometimes referred to as Egg Peritonitis (or ‘EYP’ for short), is a common condition seen in backyard hens of all ages, from the point of lay onwards. It is an infection established within the coelomic cavity of hens, caused by the presence of an ectopic yolk within the coelom (main body cavity). Egg yolk peritonitis is a common condition seen in backyard hens of all ages
It is important to distinguish egg yolk peritonitis from egg-binding in chickens, and this should be determined by your vet. The general condition of the hen, along with any evidence of an egg being stuck (sometimes in combination with x-rays) must be used to determine whether she has a simple obstruction, or is suffering from egg yolk peritonitis; as egg binding is relatively rare in backyard hens in comparison.
What causes Egg Yolk Peritonitis? Once your hens reach point of lay, the left ovary (the right ovary is usually non-functional in most birds) will begin producing ‘ova’ (yolks). These are then passed to the infundibulum (oviduct) which, in normal egg production, will ‘catch’ the yolks, to begin transporting them through the rest of the reproductive tract until they are eventually expelled as fully-formed eggs.
However, in a bird suffering from Egg Yolk Peritonitis, the yolk is not caught by the infundibulum, but is instead released into the coelomic cavity. Here, it provides the perfect growth medium for bacterial growth, with E. coli being most commonly isolated from affected birds.
Once the infection has become established, the infection will infiltrate throughout the coelom and cause a widespread peritonitis.
How can I tell if my hen is suffering from Egg Yolk Peritonitis? To catch egg yolk peritonitis early, you must be extremely vigilant of your laying flock
The issue with hens, as an example across all birds, is that generally speaking most are prey species, and as such will do their utmost to disguise and hide any indication that they are feeling unwell. They are therefore a) less likely to appear tempting to a predator and b) are far less likely to get isolated and bullied by the rest of the flock. This sadly means that generally by the time a chicken is looking overtly ‘ill’ she is most probably very close to death. Therefore, vigilance must be paramount when inspecting your birds, which should be done at least on a daily basis.
These are some of the important signs that should be used to indicate that your chicken is possibly feeling unwell, and should seek veterinary attention as soon as possible:
Pale comb/wattle
Eyes are dull, may be partially/fully closed
She’s not as keen as the rest to eat and drink
May be keeping herself away from the rest of the flock, usually tucked up in a nest-box/coop
Tail may be lowered
Difficulty/reluctance to move about
Reluctant to walk around and scratch; lack of interest in surroundings
Any evidence of discharge from the eyes, nose or mouth
Going off lay
Loss of condition – can be assessed by feeling over the keel (breast) bone muscle mass: in chronically ill birds they often lose the majority of this muscle mass
Faecal matter stuck around vent
Look in poor feather condition (not preening)
Any obvious injury (wound, limping, falling over)
Two healthy young Silver Sebright pullets; a breed less susceptible to egg yolk peritonitis due to having a reduced rate of egg laying compared to hybrid hens
Although the signs listed above will provide a good indicator as to whether your bird may be sick, some or all of the above may be displayed by a hen suffering Egg Yolk Peritonitis. As such, any ill bird that has gone off lay, potentially lost muscle mass over her keel, or is looking in general in poor condition should be checked by a veterinary surgeon. Hens with Egg Yolk Peritonitis, in combination with the signs mentioned above, will usually have a swollen abdomen. This is due to the infection within the coelom causing fibrin deposition and fluid accumulation, and it is usually this that is the give-away sign that you have a bird that is in the more advanced stages of Egg Yolk Peritonitis.
How is Egg Yolk Peritonitis diagnosed? Fluid may be drawn out of the coelom by a veterinary surgeon in order to assess the sample for evidence of Egg Yolk Peritonitis. X-rays may also be required in order to rule out egg-binding. In larger commercial flocks, or where a bird is found dead, Egg Yolk Peritonitis may be diagnosed by your vet performing a post mortem.
Can Egg Yolk Peritonitis be treated? Sadly treatment for Egg Yolk Peritonitis is rarely successful, and the majority of birds are too sick by the time they are seen by a vet.
The best chance of successfully treating egg yolk peritonitis is to catch the disease early, and this can only be achieved by being extremely vigilant of your laying flock.
The earlier a case of Egg Yolk Peritonitis is diagnosed, the better the probable outcome. If a bird is to be treated, antibiotics and good, attentive nursing care are essential.
About Elliott Simpson
With an interest for exotic and in particular a passion for avian medicine, Elliott completed an externship in Avian Medicine & Surgery at the Abu Dhabi Falcon Hospital in the UAE during his final year of Vet School. Elliott currently works as a veterinary surgeon at Veterinary Centre Westover, Norfolk.
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