Sour Crop

Causes

Sour crop or thrush in chickens is caused by the Candida Albicans yeast in the crop. 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 birds body. It is more common in growers than adult birds.

Symptoms

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

Treatment.
Nystatin or Ketoconazole are the treatments that vets will usually prescribe. They are POM-V (vet prescription only medications) that you will need to obtain from your vet. See categories of veterinary medicine in the UK for further information.

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 it's difficult to get to the vets. I haven't tried this myself before.

Other Similar Conditions:

There are other conditions of the crop that effect chickens, such as an Impacted Crop and a Pendulous Crop