A pendulous crop is when the crop gets blocked and the food stretches the crop so that it hangs down lower than it should do (and often swings 'like a pendulum' as the bird moves around).
Whilst a chicken may be able to live for some time like this and appear to be in no pain, there is damage being done to the muscles in the crop due to the weight of the food and the more food that goes into it, the more it is being stretched so it is best to address the problem sooner than later.
Causes: This problem is very similar to an impacted crop, but in the case of a pendulous crop, the crop has been stretched by the weight of the food inside the crop and the muscles have been stretched and damaged and the crop is unable to push food down to the proventriculus.
Treatment - Mild Cases: A pendulous crop can be emptied in the same way as you would for an impacted crop, but vets usually advise putting the bird onto water for 24 to 48 hours in mild cases before gradually re-introducing their food.
Treatment - Serious Cases: The contents of the crop should be softened before turning the bird upside down to empty the crop. Whilst this sounds difficult, it is in fact quite straight forward and usually successful in most cases.
Emptying a chicken's crop is a two person job, you will need to turn the bird upside down to empty the crop through the beak.
First, pour either Liquid Paraffin, warm water or a couple of teaspoons of Olive Oil down the throat and massage the crop for 5 minutes. Whilst holding the bird firmly, turn the bird upside down and massage the contents out through the beak for a short while - the bird needs a rest to breathe! 10 seconds or so and no longer at a time, before turning the bird back up the right way. If you are not confident in doing this, you should of course take the bird to a poultry vet.
Treatment - Extreme Cases: In extreme cases, if the crop is emptied in the same way as descibed for serious cases, the muscles are badly damaged and too weak to function correctly so the crop will usually fill back up again.
Similar crop conditions that you might encounter are: Sour Crop which is caused by a yeast in the crop and recognised by a putrid smell coming from the beak and an 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.