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Sour and Impacted Crop in Backyard Chickens

Sour crop and impacted crop in backyard chickens are two slightly different issues, both of which can be fairly easily remedied as long as you now how to identify that there's something wrong.


As some of you know, my friend Yvette lost her beloved hen Lily to sour crop this past January. Even with the help of her vet, she was not able to save Lily. 

This prompted her to research sour crop in an effort to try and prevent it from happening again - or to be able to successfully treat it the next time if it does happen.

Sour and Impacted Crop in Backyard Chickens

When Yvette asked if she could write a blog post for me about sour crop, she said, "If it saves even one chicken, Lily's death will not have been in vain.  It is so hard to lose a pet, and a chicken is no different." 

I agree. And hope you do as well.  We hope that you will find this post informative, but hopefully never have to use the information in it!

What is a Chicken Crop?

The chickens' crop is located beneath the neck and just to the right of the center of the breast area.  When chickens eat, the food goes directly into the crop, which will become engorged until the food continues through the digestive system.

The entire digestive system is roughly twelve inches long with the mouth at 1 inch, the crop at 3 inches, the stomach at 5 inches, the intestine between 6-11 inches and the rectum at 12 inches. If there is an infection or blockage anywhere along the digestive tract, the chicken can end up with a stopped-up crop.

The process of fully emptying the crop can take several hours, and generally happens overnight, depending on the amount of food ingested. 

Each evening your chickens' crops will be full and bloated, ranging from about golf ball size to tennis ball size, depending on how much each chicken has eaten throughout the day. 

Each morning, the crop should be empty, and the extended crop should not be present. If the chicken's crop has not emptied overnight and is still bulging, that can be a sign there's a problem.

What is Sour Crop?

Sour crop is caused when the crop does not fully empty.  This may cause the contents to become fermented, resulting in a bacterial / yeast infection within the crop. 

The chicken will begin to eat less, because the crop is still full and unable to empty. Nutritional deficiencies can quickly result.

What Causes Sour Crop?

There are some things that can contribute to sour crop including:

  • long grasses and plant fibers
  • excessive amounts of bread or pasta
  • moldy feed
  • inadequate amounts of grit
  • inadvertently swallowing pieces of plastic, rubber bands or other indigestible substances that can't be easily broken down and allowed to pass from the crop

Prevention of Sour Crop

Like most things, prevention is easier than a cure. Prevention of sour crop includes:

  • limiting access to long or tough plant fibers*
  • adequate fresh water with apple cider vinegar added several times a week (in a ratio of 1 Tablespoon/gallon of water) to keep the body alkaline versus acidic
  • a smashed clove of fresh garlic in the water
  • plain yogurt on a weekly basis
  • ensuring the area the chickens roam in is free of string, rubber bands, twine, etc

*this refers only to hand feeding chickens long strands of grass. Interestingly, free ranging chickens rarely suffer sour or impacted crop.

So letting your chickens free range is fine and short (1/2" or so) pieces of grass are okay, but something like mowing the lawn and dumping in the clippings to your chickens is asking for trouble, since the strands are likely going to be several inches long.

**if your chickens do free range at least part of most days, they'll pick up enough small stones and coarse dirt to act as grit in their crop to help digest their food. If not, providing a small container of coarse dirt of commercial grit in the coop or run is a good idea.

Sour crop can also be a side effect of any illness that causes dehydration. Unfortunately crops swollen with food will draw even more water from the bloodstream, leading to further dehydration and more food backup. 

Therefore liquids are extremely important in treating sour crop and clean, fresh water is a necessity in the run at all times.

Symptoms of Sour Crop

Sour crop is best identified in the morning. If the crop is extended and feels squishy,  then the crop has not emptied as it normally should. If the crop is extended and hard, you're likely looking at impacted crop instead. See below for more information about impacted crops.

You also will notice a ‘sour’ smell coming from the beak of the chicken and in some cases a foul-smelling liquid may also leak out of the chickens mouth.

Your chicken may show signs of being lethargic. She may isolate herself – not eating or ‘scratching around’ as normal chicken behavior. She may vomit and her skin may appear red instead of pink.

  • Extended, squishy crop
  • Sour smell coming from the beak
  • Foul-smelling liquid leaking out of the mouth
  • Lethargy
  • Self-isolation
  • Vomiting

Treatment for Sour Crop

If you suspect sour crop, there are several things you should do:

  • isolating your chicken in a warm, quiet area 
  • limiting feed intake
  • holding her upside down and gently massaging the crop in the direction of the head and carefully trying to induce vomiting
  • encouraging her to eat some yogurt or olive oil 
  • keeping her drinking plenty of water with apple cider vinegar 
  • sprinkling a bit of cinnamon over some plain yogurt and adding a drop of oil of oregano

Apple cider vinegar is an anti-fungal, and often avian vets will recommend it for cases of sour crop, since sour crop is basically a yeast infection.

Oil of oregano ( not oregano essential oil or oregano oil) is a natural antibiotic that can be helpful as well. It has been studied in commercial poultry houses in conjunction with cinnamon to work in place of antibiotics. 

This is a good option for the oregano oil since it's already diluted in olive oil. Oil of Oregano diluted in olive oil can help prevent sour crop and get things moving again.

When It's Time for a Vet Visit

If after several days of home remedies the crop still seems abnormal, it is probably time for a visit to your vet.  

There are several options that can be considered for treatment, including fluid injections and/or antibiotics, however it’s best to seek direct advice from an Avian Veterinarian at this point.

Sour Crop vs. Impacted Crop

A hard crop can signal impacted crop which is a slightly different issue, also caused by large items in the crop that can't pass through the digestive system.

Impacted crop can be treated by lubricating the crop/digestive tract with vegetable oil in an eyedropper through the mouth and massaging the crop to try and break up the blockage, or in extreme cases actually slitting the crop open with a scalpel and removing the blockage.

An impacted crop can actually press against the windpipe of the chicken and suffocate the hen.

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Many thanks to Yvette for doing all the research and writing up this information to share with you.  


The Poultry Pages/  

Chicken Vet UK

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