Intracranial lipomas are a congenital malfunction that occurs in Crested Duck breeds. Crested ducks possess a distinct feather crest on their head which has been associated with very conspicuous alterations on brain morphology. The feather crest occurs on top of a cushion of fat and connective tissue in the parietal part of their skull (this differs from crested chicken breeds, where their crest is situated on a bony protuberance). Underneath the cushion of fat lies the cranium of the brain, which is often perforated and/or significantly reduced in comparison to other duck breeds. Many crested ducks contain a lipoma (a benign tumor composed of fat tissue) inside their skulls. Depending on the size and position of the lipoma in the brain, it often causes potentially harmful changes in behavior and effect on central nervous system (CNS) function.
Ducks with intracranial lipomas may be asymptomatic or associated with seizures and a variety of clinical manifestations depending on the size and location. Some of the most commonly observed being:
- Motor incoordination (ataxia), which may appear as a tottering walk.
- If ducks fall on their backs, they aren't able right themselves.
- Erratic head movements
- Abnormally small eyes
- twisted or crooked neck
- Abnormal changes in behavior
- Inability to stand
The length of time before neurological signs start to develop can vary and can be present upon hatch or may not start to show until several weeks to months later.
Surgical removal is often unfeasible and conservative treatment assumes a major role controlling seizures