Crop stasis, commonly referred to as “sour crop,” is a condition in which a chicken’s crop fails to empty properly.This disrupts the normal movement of food and fluids through the gastrointestinal tract, leading to dehydration and rapid weight loss. If the bird continues to eat or drink, the contents accumulate in the crop, causing it to become enlarged. In these cases, the bird’s body weight may remain misleadingly normal due to the retained material in the crop.
As feed remains stagnant, it often begins to ferment or decompose, creating an environment for yeast, fungal, or bacterial overgrowth. While yeast infections are commonly associated with sour crop, they are often a secondary issue rather than the primary cause. Because affected birds can deteriorate quickly, prompt veterinary care is important.
The crop is a pouch-like extension of the esophagus located at the base of the neck. It serves as a temporary storage site where the initial stages of digestion begin. Under normal conditions, food passes from the crop into the proventriculus (the glandular stomach) and then continues through the rest of the digestive tract via coordinated muscular contractions known as gastrointestinal motility.
Any disruption in this motility, or a physical obstruction within the digestive tract, can cause food to back up into the crop. When this occurs, the retained material may decompose, leading to secondary infection and worsening of the condition.
Crop stasis may result from primary issues affecting the crop itself or secondary conditions elsewhere in the body. Most cases are secondary.
Causes
Primary (crop-related) causes:
- Crop infections: Yeast, fungal or bacterial.
- Crop impaction: Caused by ingestion of indigestible or fibrous materials such as long grass, string, twine, bedding, sand, or other foreign objects
- Trauma
- Parasitic infections: Including Capillaria spp and Gongylonema ingluvicola, which can inhabit the crop lining.
Secondary causes:
- Reproductive disease: Conditions such as egg yolk peritonitis, internal laying, oviduct impaction, ovarian tumors, or salpingitis can compress or disrupt the gastrointestinal tract, impairing motility.
- Tumors: Growths within or near the gastrointestinal tract may cause obstruction, adhesions, or nerve damage (e.g., Marek’s disease affecting nerve function).
- Infections: Gastrointestinal, respiratory, or reproductive infections may interfere with normal digestion and motility.
- Foreign body ingestion: Materials may obstruct or damage other parts of the digestive tract.
- Heavy metal toxicity: Lead or zinc ingestion can impair gastrointestinal function.
- Intestinal parasites: Such as Ascaridia galli, Capillaria spp, and Tetrameres spp, which can damage or obstruct the intestines.
Treatment
Treatment depends on the underlying cause but typically includes supportive and medical care:
- Fluid therapy: Administered subcutaneously or intravenously in dehydrated birds.
- Antimicrobial therapy: Antibiotics and/or antifungal medications as indicated.
Motility agents: Medications such as metoclopramide or cisapride may be used if no obstruction is present.- Gastrointestinal protectants: Such as sucralfate.
Veterinary guidance is essential, as improper treatment can worsen the condition.
