Sour Crop

The crop is part of the oesophagus (food pipe) at the base of the neck and is the first stage of digestion for a chicken, it contains food, water and grit (used for digestion).  When full, the crop is tennis ball sized. You can sometimes feel the contents of the crop when handling chickens and it can certainly be seen immediately after a chicken has been eating.

Sour crop in chickens (sometimes called Thrush) is caused by a fungal species of yeast Candida Albicans in the crop. This disrupts the normal bacteria usually found in the crop and leads to a thickening of the crop wall causes problems. If left untreated, death can occur. Sour crop in chickens can easily be identified by the putrid smell that comes from the bird’s mouth.

Sour crop can occur after a course of oral antibiotics (such as Baytril or Tylan) or if there has been a shortage of Vitamin A in the bird’s body but mouldy / poor quality feeds or strange diets containing the wrong foods are more common. Sour crop appears to be more common in growers than adult birds.

Chickens crops look big when full (up to tennis ball size). It is normal for the crop to fill like this but it should empty. If in doubt, check the crop has emptied in the morning before a bird has eaten.

Symptoms: Sour crop is very easy to diagnose. There is a terrible smell coming from the bird’s mouth and once you have smelt it, you will never forget it! Birds can sometimes be lethargic, dull and will gradually lose their condition.

Treatment: I would strongly advise veterinary assistance for this condition. Your vet may prescribe Nystatin, Ketoconazole, or copper sulphate and possibly a course of antibiotics.

Orally adding fluids to the crop and then emptying it by turning the bird upside down for short periods (so it doesn’t suffocate) is usually possible but does nothing for the infection, and there is a real risk of the bird choking when doing this which is why veterinary assistance is recommended. A veterinary procedure would probably use local anaesthetic, cut the crop open, empty it, flush it out with saline solution, stitch the crop back up and treat the infection.

I have found many references to this condition in pigeons as well as in poultry. Some experienced pigeon fanciers have recommended using Garlic. They believe it works faster and better than Nystatin so might be worth a try if you cannot get to a vets. I haven’t tried this myself and again would urge you not to let this condition get out of control.

Similar Conditions


There are other conditions which can produce similar signs:

  • Impacted Crop where there is a blockage in the crop and the crop is full and feels like dough but has not stretched to become pendulous. There will not be the smell that you get with sour crop.
  • Pendulous Crop is when the crop becomes blocked and the weight of the food and weak muscles stretch the crop so that it hangs down like a pendulum.

Tip: The tags under the related articles below allow you to view other articles tagged with those symptoms.

The following two tabs change content below.

Tim Daniels

Tim is the founder of the poultrykeeper website and lives in Bedfordshire, UK. He keeps Light Sussex large fowl, Silkie bantams and hybrid layers for eggs, Abacot Ranger ducks, Brecon Buff geese and some quail.

Latest posts by Tim Daniels (see all)