The crop is a muscular pouch at the base of the throat where food is stored and softened before passing to the proventriculus and ventriculus for digestion. Crop stasis, also called crop slowdown or sour crop, occurs when the crop fails to empty at a normal rate. Food ferments in the stagnant pouch, producing gas and harmful bacteria or yeast, and the bird cannot take in adequate nutrition.

Causes

In baby birds, crop stasis often results from formula that is too cold, too thick, or contaminated. In adult birds, causes include fungal infections (particularly Candida), bacterial infections, foreign body ingestion, crop burns from overheated formula, thyroid dysfunction, heavy metal poisoning, and viral diseases like proventricular dilatation disease (PDD). Stress and sudden dietary changes can also trigger an episode.

Symptoms

A visibly full, doughy, or distended crop that does not empty within the expected time frame is the primary sign. In hand-fed chicks, this means the crop still feels full at the next scheduled feeding. Adult birds may regurgitate foul-smelling material, lose weight, appear lethargic, and develop a wet or matted appearance around the beak. Gas bubbles may be visible through the skin of the crop in some species.

Why it is an emergency

Stagnant food in the crop provides an ideal medium for bacterial and fungal overgrowth. Aspiration of crop contents into the trachea can cause fatal pneumonia. Malnutrition and dehydration advance quickly in small birds. A crop that remains distended for more than 12 hours beyond normal emptying time warrants veterinary evaluation.

Veterinary treatment

The vet will assess the crop contents through palpation and may perform a crop wash or aspirate. Cytology of crop fluid identifies yeast or bacterial overgrowth. Treatment depends on the underlying cause and may include antifungals (nystatin for Candida), antibiotics, motility-enhancing drugs, and careful rehydration. Foreign bodies require endoscopic or surgical removal.

Prevention

Feed hand-reared chicks with properly prepared formula at the correct temperature (approximately 40 to 42 degrees Celsius). Keep feeding equipment scrupulously clean. For adult birds, provide a balanced diet, avoid sudden food changes, and bird-proof the environment to prevent foreign body ingestion. Regular veterinary checkups help catch subclinical infections before they cause crop problems.

Veterinary disclaimer: This article is for general education only and does not replace an examination by a licensed avian veterinarian. If your bird’s crop is not emptying normally, consult a vet without delay.