Sour crop is a yeast infection in your chicken’s crop, the expandable pouch at the base of the neck where food is stored before digestion. It’s caused by an overgrowth of Candida, the same type of fungus behind thrush in humans. Treatment involves emptying the crop, restoring its natural acidity, and rebalancing the beneficial bacteria that keep yeast in check. Most mild cases resolve within a few days of home care, but severe or recurring infections may need antifungal medication from a vet.
How to Confirm It’s Sour Crop
Before you start treatment, make sure you’re dealing with the right problem. Check your chicken’s crop first thing in the morning, before she eats. A healthy crop should be empty or nearly flat by morning. If the crop still feels full, squishy, and dough-like (not hard), and you notice a foul, fermented smell coming from her beak, that’s the hallmark of sour crop. In more advanced cases, you may see a white film or coating inside the mouth and along the throat, where the yeast infection has spread upward from the crop.
This is different from an impacted crop, which feels firm or hard like a packed ball because food is physically stuck. Sour crop feels soft and balloon-like, filled with gas and fermenting liquid. Sometimes impaction leads to sour crop, since food sitting too long in the crop creates the warm, nutrient-rich environment yeast thrives in. A normal crop empties in roughly four to six hours. When that process stalls, Candida takes over.
Step 1: Withhold Food for 24 Hours
The first goal is to let the crop empty itself. Withhold all food and water for 24 hours so the crop can drain naturally without new material coming in. This starves the yeast of the sugars and starches it’s feeding on and gives the crop a chance to contract back toward its normal size.
During this fast, keep your chicken separated from the flock so she can’t sneak food from feeders or forage on the ground. A dog crate or small pen with clean bedding works well. While 24 hours without water sounds harsh, a single day is tolerable for an adult chicken and is necessary to break the cycle of fermentation.
Step 2: Administer Apple Cider Vinegar
Once the crop has had time to empty, give a small dose of apple cider vinegar (ACV) directly into the beak using a syringe (without a needle). Dilute the vinegar according to the manufacturer’s recommendation, typically around one tablespoon per gallon of water. Gently syringe the diluted solution into the side of the beak, not straight down the throat, to avoid aspiration into the lungs.
ACV lowers the pH inside the crop, making the environment less hospitable to Candida. Use raw, unfiltered apple cider vinegar with the “mother” culture, since the live bacteria contribute to rebalancing the crop’s microflora.
Step 3: Slowly Reintroduce Food and Water
About 12 hours after giving the ACV, offer a few small sips of lukewarm water and roughly a teaspoon of soft food. Plain, unsweetened yogurt or scrambled egg are good choices because they’re easy to digest and low in the starches that feed yeast. Avoid scratch grains, bread, or anything high in sugar or carbohydrates at this stage.
Over the next two to three days, gradually increase portion sizes and transition back to her normal layer feed. Check the crop each morning before she eats. If it’s emptying overnight and the sour smell is gone, she’s recovering well. If the crop is still distended and smelly after two or three days of home treatment, the infection is likely too established for ACV alone.
When You Need Antifungal Medication
For cases that don’t respond to the fasting and ACV protocol, a vet can prescribe nystatin, an antifungal medication given orally. Nystatin works directly inside the digestive tract without being absorbed into the bloodstream, which makes it effective against crop yeast while being relatively gentle on the bird. It’s typically given by mouth two to three times a day for several days.
Copper sulfate in drinking water is another option used by experienced poultry keepers. Mississippi State University Extension recommends dissolving half a pound of copper sulfate and half a cup of vinegar into one gallon of water to make a stock solution, then dispensing that stock at one ounce per gallon for the final drinking water. A simpler method is dissolving one ounce of copper sulfate and one tablespoon of vinegar directly into 15 gallons of water. Use either solution as the sole water source during the infection. Be precise with measurements, as copper sulfate is toxic at higher concentrations.
Support Recovery With Probiotics
Sour crop is fundamentally a problem of microbial imbalance. The beneficial bacteria that normally keep yeast in check have been overwhelmed. Restoring that balance speeds recovery and helps prevent recurrence. Probiotic supplements containing Lactobacillus strains are well suited for poultry because they actively inhibit pathogenic microbes while promoting beneficial ones.
You can find poultry-specific probiotic powders that mix into water or feed. Plain yogurt with live cultures also provides some benefit in the short term. Start probiotics once your chicken is eating again and continue for at least a week after symptoms resolve. This is especially important if the bird has recently been on antibiotics, since broad-spectrum antibiotics wipe out the normal gut and crop bacteria, creating exactly the conditions Candida needs to proliferate.
What Causes Sour Crop in the First Place
Understanding the triggers helps you prevent a repeat. The most common causes are:
- Antibiotic use. Broad-spectrum antibiotics destroy the beneficial bacteria in the crop, leaving open space for yeast to multiply rapidly.
- Moldy or spoiled feed. Feed that’s been stored improperly or left in damp conditions introduces additional fungal organisms directly into the crop.
- Dirty water systems. Slimy waterers and stagnant water are breeding grounds for Candida and other pathogens.
- High-carbohydrate treats. Bread, pasta, and sugary scraps provide the exact fuel yeast needs to overgrow.
- Crop stasis from other causes. Anything that slows crop emptying, whether it’s a partial blockage from long grass, string, or other foreign material, creates a warm, nutrient-rich environment perfect for yeast.
- Vitamin and protein deficiencies. Poor overall nutrition weakens the immune system and disrupts the microbial balance in the digestive tract.
Young chickens are more vulnerable than adults, and birds that are already immunosuppressed from parasites or illness are at higher risk.
Preventing Sour Crop Long Term
Prevention comes down to good husbandry. Store feed in sealed containers in a dry location and discard anything that smells musty or shows signs of mold. Clean waterers at least twice a week, scrubbing away any biofilm buildup. Adding a small splash of ACV to the flock’s water a few times a week (roughly one tablespoon per gallon) helps maintain a mildly acidic environment that discourages yeast without harming the birds.
Limit starchy, sugary treats to occasional small amounts. Make sure your flock always has access to appropriately sized grit so they can grind food efficiently and keep the crop moving. If a chicken needs antibiotics for a bacterial infection, follow up with a course of probiotics once the antibiotics are finished. Avoid using antibiotics longer than necessary, and never use them “just in case.” The connection between unnecessary antibiotic use and sour crop is well established. Keep living conditions clean and dry, manage parasite loads with regular checks, and provide a balanced layer feed as the foundation of their diet. These basic steps eliminate most of the conditions that allow Candida to shift from a harmless resident of the crop to an infection.