Sour Crop in Chickens - Symptoms and Treatment

Sour crop in chickens

Sour crop is a common illness in chickens. We hope that you never have to deal with it, but if you do, a bit of information will go a long way.

The first step to treating sour crop is recognising the symptoms. There are several other crop problems, including impacted crop and pendulous crop, that can be mistaken for sour crop. If your chicken's crop does not empty overnight and become flat, this is a symptom of a crop problem.

What is a crop?

A chicken’s digestive system is very different to a human’s, and the crop is the first “station” of this system. Basically, the crop is a small pouch where swallowed food is stored. Food held in the crop is softened and gradually released for digestion. This lets chickens eat a lot at one time and then digest it more slowly while they preen, bathe or sleep.

The crop is found low on the chicken’s chest, to the right of the breastbone. It is usually at the most prominent part, before the breast curves down under the bird.

When a chicken has eaten, the crop can be easily felt, and when a chicken has eaten a lot, the crop may even protrude visibly. Being able to see and feel the crop after your chicken has eaten is normal and is not a sour crop symptom. 

But when a chicken hasn't eaten, for example first thing in the morning, the crop should be empty. An empty crop is flat and you cannot feel it. 

With all three crop problems - sour crop, impacted crop and pendulous crop - the crop does not empty properly and you will be able to see or feel it, even first thing in the morning. Being able to feel the crop when your chicken hasn't eaten is the sign of a problem.

Normal chicken crop

What are sour crop symptoms?

You can diagnose sour crop by examining your chicken's crop.

A swollen crop that is squishy to touch is the most obvious symptom of sour crop in chickens. Impacted crops are swollen and hard, and pendulous crops are distended but feel relatively normal.

Symptoms of sour crop can include:

  • A squishy, swollen crop
  • Lethargy
  • Lack of appetite
  • Weight loss
  • Sour, disgusting-smelling breath
  • Liquid or gas exiting the beak, particularly if you gently touch the crop
  • White patches in the mouth

Many of the symptoms of sour crop can also be caused by other chicken illnesses. If you have a chicken that is displaying any sour crop symptoms, check it first thing in the morning to make a diagnosis. Remember, all crop problems in chickens will require care and treatment. 

What causes sour crop in chickens?

Sour crop is the result of a yeast infection in the crop. This occurs when the normal bacteria in the crop is disrupted. The most common cause of sour crop is Candida albicans, the same strain of yeast that causes thrush in babies. 

Candida species are found everywhere in the environment, including in mouldy or rotten food and in chicken poop. Usually they don't cause a problem, but if your chicken has other problems then sour crop can occur. Stress, unsanitary conditions or overcrowding often lead to sour crop infections in chickens. If a chicken is not healthy or is exposed to anything that might interfere with digestion then sour crop can result.

Common causes of sour crop in chickens include:

  • Crop impaction (impacted crop) where a blockage in the crop has become infested with candida
  • Ingesting foreign objects such as metal, plastic or string, which may damage the crop or cause impaction
  • Severe worm infestation
  • Excessive antibiotic use that has disrupted the normal balance of gut flora
  • Unsanitary conditions, particularly water or feed that is contaminated with faeces
  • Mouldy or rotten food
  • A poor diet, for example with lots of processed foods or sugar
  • Stress
  • Some chicken diseases

Whatever the cause, the treatment of sour crop is the same.

Sour crop treatment for chickens

To treat sour crop, begin by isolating the sick bird. Provide ample water. 

Clean and  disinfect feeders and waterers in the main coop in order to prevent the yeast infection from spreading. Some sources recommend adding Apple Cider Vinegar to the drinking water in the coop and in the hospital pen in order to combat the yeast infection.

In mild cases of sour crop, home treatment may be effective. However, if your chicken has not improved in a couple of days, veterinary treatment is recommended. 

Home treatment for sour crop includes:

  • Gently massaging the crop to try to shift any blockages (do not do this if it causes liquid to overflow) 
  • Offering grit
  • Treating with a probiotic or Apple Cider Vinegar

Although you can attempt to empty the crop yourself or to flush it with Epsom salts, this is a risky option. Chickens cannot throw up, so any liquid leaving the crop can easily overflow into the lungs causing asphyxiation. Aspirating even a small amount of liquid can be fatal.

In severe cases of sour crop, particularly where the bird has been ill for some time, veterinary treatment is the best option. Most vets will flush or empty the crop and treat the chicken with an anti-fungal medication.

Although you may be able to treat the Candida infection with human thrush medication, there is no research into withholding periods for meat or eggs, so this is not recommended.

Untreated impactions and sour crop can lead to death. In the event of recovery, chickens may be left with a pendulous crop which is an untreatable swelling of the crop that makes it difficult for chickens to eat normally and hinders movement.

Preventing sour crop

As with everything, prevention is better than a cure. Some chickens are more susceptible to sour crop than others and if birds are unhealthy or stressed, the illness is much more likely. 

Generally, sour crop can be prevented by:

  • Worming chickens twice yearly
  • Feeding a balanced, high-quality diet free from mouldy or rotten foods
  • Ensuring feed and water are not contaminated by faeces with a Dine a Chook Feeder and Drinker
  • Picking up uneaten food so it does not become mouldy
  • Keeping grass relatively short
  • Ensuring chickens don’t have access to foreign objects that may cause damage, in particular pieces of string and plastic
  • Giving ample access to grit
  • Avoiding long-term antibiotic use
  • Following antibiotics with a probiotic
  • Avoiding scraps like processed and sugary foods

In healthy birds, and particularly free-range birds with a sanitary coop, crop problems are relatively uncommon. For advice on how to make sure your chickens are healthy, happy and unlikely to suffer from sour crop, check out these blog articles:

Happy chicken keeping!

Rachael at Dine a Chook Australia