This is a condition that often occurs in nestlings but can also be seen in fledgelings and adults.
The food in the crop does not continue its route through the digestive system and stagnates in the crop, causing a build up of bacteria.
In nestlings this can happen if they are fed when they are cold, if the formula itself is too cold or if the formula is too thick.It can also be caused by a canker nodule in the proventriculus or by a yeast infection, both of which would need treatment with prescription medicines.
It is often necessary to flush the crop, but this is a job for a veterinarian or for an experienced rehabber. As an interim measure the pigeon can be given up to 10 cc (depending on the size and age of the bird affected) of warm water with a pinch of bicarbonate of soda in it.
Warmth can sometimes help, so place the pigeon on a heat pad.
Metaclopramide, only available for the vet, increases crop motility and can be used for crop stasis (it is usally used to stop vomiting). 1 drop for every 100 grams bodyweight twice a day.
This is sometimes seen in young ferals that have been fed on very fresh bread or that have been treated with antibiotics.
The symptoms of a yeast infection are vomiting and crop stasis.
A pigeon with yeast infection might look under and will probably have creamy dots inside the mouth, but a vet can confirm the condition by swabbing the inside of the pigeon's mouth and examining the results under a microscope.
Yeast infections are treated with Nystatin, which is a prescription medicine. It works by destroying the yeast on contact so should be dripped into bowl of the lower beak, allowing the pigeon to swallow it and target yeast in the mouth and throat as well as in the crop and intestines.