Recently one of my young layers died unexpectedly so I sent her body to the provincial Animal Health Centre for a necropsy. I got the results back in two stages: the gross examination with the cause of death and then, further lab work that included bacteriology, histopathology and molecular diagnostics. I’m not a veterinarian so I had to do a bit of research to translate the terminology into layman’s language.

Surprisingly, to me anyway, she died of visceral gout, a result of impaired kidney function. Scanning through the lab work I noticed that she also had a receded ovary, mild egg yolk peritonitis and bacterial infections.

Having never had a hen with egg yolk peritonitis (EYP) I did a bit more reading to understand what had been going on, unseen, for her.

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). They are  passed to the infundibulum (oviduct) which, in normal egg production, will begin transporting them through the rest of the reproductive tract until they are eventually laid as fully-formed eggs. In a hen with EYP, the yolk is not caught by the infundibulum, but is instead released into the coelomic cavity.

Hen Reproductive System
Hen Reproductive System

EYP is inflammation in the peritoneum (tissue covering the inside of the abdomen and most organs) caused by the presence of yolk from a ruptured egg or a retained egg in the oviduct. The yolk may result in only mild inflammation and be absorbed by the peritoneum. Unfortunately the yolk is also a medium for bacteria, which can lead to infection. My hen’s lab work revealed the presence of both E. coli and Staphylococcus, which are just two, of several, bacteria associated with EYP.

Betty’s primary condition was avian gout, with EYP being her secondary issue. It is common that EYP occurs as a by-product related to other reproductive issues: salpingitis, impaction or torsion of the oviduct, ovarian neoplasia, cystic ovarian disease, defective egg syndrome and obesity.

As I mentioned, Betty’s death was unexpected. She appeared somewhat ‘off’ the day before her death, but her symptoms weren’t a red flag for how serious her condition was. Many birds with gout are often diagnosed post-mortem because they are functioning fairly normally prior to their demise. I currently have a flock of almost 30 adult birds and just as many chicks, of varying ages. With that number it’s sometimes difficult to monitor individuals and notice small changes that might alert me to an underlying health issue.

When I sent in the paperwork for the necropsy I stated that I thought she was eating, drinking and laying. Clearly I was wrong: her crop was full and although she was drinking, she was dehydrated (a symptom of gout). With a recently receded ovary and mild chronic EYP she couldn’t have been laying. Her post-mortem was revealing in that she didn’t display any overt signs before her death.

Symptoms of EYP include:

  • lethargy
  • depression
  • excessive sitting in the nest box
  • decreased appetite
  • delayed molt
  • laying deformed or soft-shelled eggs
  • ‘penguin stance’ (standing upright/waddling)
  • fluid retention: distention of the abdomen, difficulty breathing

When I read about the methods for diagnosing EYP I realized they were out of reach for most chicken keepers, who don’t have access to avian veterinarians or the funds to pay for their services. To figure out if a hen is affected, vets use a combination of methods: health history, symptoms, physical exam, and sometimes a variety of diagnostic imaging equipment and lab tests.

A simple exam, palpating the abdomen, might reveal the presence of eggs in the oviduct or ectopic eggs within the abdomen, ovarian masses or displacement of the ventriculus. Blood work measuring white blood cells could indicate inflammation or infection and cultures can identify what bacteria might be the cause.

For those with deep pockets, who can both afford further diagnostic work and are exceptionally dedicated to the survival of their bird: abdominal fluids can be extracted via needle for testing; x-rays and ultrasounds can show accumulated egg material or lesions. I’m wondering to what end someone would go to these lengths if the prognosis isn’t a full recovery.

Treatment varies depending on the cause and severity of the condition.

If there is no secondary bacterial infection supportive care may be all that is required. Bacterial infections might require a combination of pain killers, anti-inflammatories, broad-spectrum antibiotics, supportive care and strategies to deter egg laying. There are some folks who put their hens on hormones to stop them from laying and, even go so far as, having them spayed.

For most small flock keepers, a severe case of EYP often means the end of the road for that bird and euthanasia is the most practical and humane option. For me, the cost of care isn’t the main driver; it’s the quality of life for our birds. I’ll do what I can to save a bird that has the potential for a meaningful life and opt to euthanize those that don’t.

If you’re really interested in seeing what a necropsy on a hen with EYP is check out this video.

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