Uric Acid Ingluviolith in a Budgerigar (Melopsittacus undulatus)

Area of Science:

• Avian medicine
• Veterinary pathology
• Comparative physiology

Background:

• Ingluviolithiasis, or crop stone formation, is a rare condition in birds.
• Previous cases often involved smaller calculi or different compositions.
• Budgerigars (Melopsittacus undulatus) are common pet birds susceptible to various health issues.

Purpose of the Study:

• To report a unique case of a large ingluviolith in an adult female budgerigar.
• To accurately characterize the composition of the ingluviolith.
• To discuss potential contributing factors and implications for avian health.

Main Methods:

• Clinical examination including palpation and radiography.
• Computed tomography (CT) for detailed imaging of the crop foreign body.
• Surgical removal of the ingluviolith (ingluviotomy).
• Chemical and crystallographic analysis: polarized optical crystallography, infrared spectroscopy, and x-ray diffractometry.

Main Results:

• A large (16 x 12 mm) radiopaque foreign body was identified in the crop.
• Initial analysis suggested a cystine calculus, but further testing revealed anhydrous uric acid crystals with a proteinaceous core.
• The calculus had a mineral-attenuating shell encrusting protein-based fibers.

Conclusions:

• This case represents a significant finding in avian ingluviolithiasis due to the calculus size and composition.
• The formation of such a large stone suggests in-crop development.
• Stress-induced coprophagia leading to urate and feather ingestion is a proposed etiology.