• Cause: failure of complete regression of second (right) Mullerian duct during embryo development.
• Signs: common incidental finding with no clinical signs. Size of cysts can vary from 2-20 cm. Large cysts act as space-occupying lesions with associated clinical signs.
• Diagnosis: clinical signs, diagnostic imaging (ultrasonography, celioscopy), celomocentesis, exploratory celiotomy, post-mortem examination.
• Treatment: monitoring of small cysts, reduction or removal of large cysts.
• Prognosis: good for small cysts; fair to poor for large cysts with secondary infection, comorbidities, or if surgery required.

• None for birds with small, incidental cysts, often a necropsy finding.
• Birds with large cysts may show signs relating to the presence of a space occupying lesion. Birds with infected cysts may show related secondary symptoms:
  • Lethargy.
  • Weakness.
  • Reduced appetite.
  • Cessation or reduced egg production.
  • Fluid-filled coelomic distention.

• Adult laying hens.

• Females.

• More common in backyard poultry compared to commercial poultry.

• Rarely effects commercial poultry performance/quality.
• Cost of investigations or surgery in individual hens may be prohibitive.

• Increased anesthetic risk in birds with large space occupying lesions.

• Most avian species retain a functional left ovary and oviduct originating from the left Mullerian duct during embryonic development.
• The right Mullerian duct normally regresses prior to hatching.
• Failure of complete regression or partial development of the second (right) Mullerian duct leads to persistence of vestigial tissues.
• Vestigial tissues can result in the formation of a cyst.

Specific

• Genetic predisposition.
• Infectious bronchitis virus outbreaks have been associated with increased incidence of cystic right oviduct.

• Variable time to clinical signs if present.

• Single bird affected.
• Group may be affected in breeding system.
• Flock incidence have been associated with infectious bronchitis virus outbreaks.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Mueller Slay A, Franca M, Jackwood M & Jordan B (2022) Infection with IBV DMV/1639 at a young age leads to increased incidence of cystic oviduct formation associated with false layer syndrome. Viruses 14 (5), 852 PubMed.
• Wakamatsu M, Yamagata T, Namikawa T & Mizutani M (2000) Hereditary persistent right oviduct in the chicken PNP/DO line. Poultry Sci 79 (8), 1075-1081 PubMed.
• Greenacre C B (2015) Reproductive Diseases of the Backyard Hen. J Exotic Pet Med 24 (2), 164-171 PubMed.

Other sources of information

• Swayne D E (2013) Diseases of Poultry. 13th edn. Wiley-Blackwell, USA.