Crop Problems

Text and photos: Monique de Vrijer Translation: Diana Hedrick

CROP PROBLEMS

The crop serves as a temporary ‘storage bin’ for the feed the chicken eats. It is often full during and at the end of the day and should normally be empty when the bird starts its day in the morning. Unfortunately ‘crop problems’ are not an uncommon occurrence and presents as symptomatic with many dif- ferent illnesses and conditions.

The Crop The crop is part of the digestive system and is an enlarged part of the esophagus at the foot of the neck where feed is (temporarily) stored and "moistened" with mucous and saliva from the mouth until the contents are moved into the stomach.

A chicken has two stomachs, the proventriculus (the glandular stomach) and the gizzard or ventriculus (also called the muscular stomach). The feed is transported from the crop into the the glandular stomach which, as the name implies, is where secretory enzymes are added to the feed mass to aid in digestion; one of which is pepsin which in turn activates the stomach to produce hydrochloric (stomach) acid lowering the PH to aid in digestion and absorption of nutrients and also helps to dissolve the calcium grit (usually oyster shell) releasing the calcium in it. These enzyme-filled gastric juices infuse the feed as it moves onwards towards the gizzard (ventriculus or muscular stomach). The gizzard is a small organ and not able to deal with large quantities of feed. It is composed of two oval shaped and thick walled powerful muscles with a tough horny lining. The gizzard retains the grit/small stones that the bird has eaten, which helps it to ‘grind’ and breakdown the feed. Once the feed has gone through the grinding process of the gizzard it enters the intestines where most of the true digestion and absorption of nutrients takes place.

When crop problems arise this is mainly due to the crop being unable to empty the contents and move them through into the proventriculus and the feed remains too long in the crop. In addition to malnutrition, the crop will become distended (sometimes enormous) and the bird will often stop eating and drinking and become very ill. Balance is often disturbed (you will notice problems when attempting to roost) and they will often swerve their head and neck back and forth and gape; sometimes behaving as though they are choking on something and shaking their head. The distended crop can feel hard or alternately very soft and swollen. With the latter, you will often notice a distinct smell coming from their mouth which originates from the swollen fermenting contents of the crop.

Right: The digestive system of a chicken. Drawing: Monique de Vrijer.

1. Oesophogus 2. Crop 3. Proventriculus and Gizzard 4. Liver and Gall Bladder 5. Small Intestine 6. Caeca 7. Large Intestine 8. Cloaca

There are many causes of crop problems and the follo- wing is a review of the most common:

Fibre Fibre is important to digestion (found in ‘green’ food (forage) and grains) and just as with humans, the fibre content (and type) is very important to poultry health and digestion. When the bird has insufficient fibre in its feed then there will be insufficient stimulation within the intestines hampering the digestive process which often results in crop stasis (the crop fails to empty). However, unlike humans, insufficient fibre is rarely a problem whereas too much fibre (this being due to basic physiological differences between the digestive systems of humans and birds) is a common cause of problems within the digestive process, which will in turn cause crop problems. Long fibrous material such as grass, straw or hay (even feathers) are also a source of crop problems in that these will often cause an impaction (blockage) leading to a knotted mass which the crop will be unable to move out of the crop pouch. The impaction or blockage may be massive (all of the contents retained and unable to be moved out of the crop) or partial (allowing some of the contents through), both having the consequence of further complications secondary to the crop stasis.

Too much fibre content combined with too little fluid intake can also be devastating, as when the chicken drinks too little and the crop is unable to function properly, then this can lead to a concretion (dehydrated food mass) which will in turn lead to the bird drinking too much and the crop becoming distended and atonic (see below), damaging the musculature so that it is unable to function properly. The clear message is that the fibre content of your bird’s diet needs to be monitored carefully particularly when digestive problems are suspected. If your birds free range, then keep them away from grass clippings which will be longer in length than they would nip off while ranging and if you wish to feed grass, then ensure it is cut in very small pieces and do not give too much at once. Chickens unused to ranging grass or those without an alternative source of feed or deficiencies will also eat fibrous material such as straw, hay or other fibrous bedding material (sometimes simply out of curiosity). Ensure therefore that your birds always have a constant source of feed even when free ranging available at all times.

‘Over’-Eating or Drinking Over-eating or drinking can also cause problems! Especially in excessively hot weather when the chickens may gorge on water. Over-eating can occur when they are offered treats or such that they are particularly fond of when they are already "full" or offered an excessive amount at one time. They will eat it all, storing it as is customary with prey, and when this happens on top of a full crop (or when an excessive amount is offered at once) then this will distend the crop and strain the crop musculature. A distended crop overstretches it muscles ... compare the situation with a balloon; when it is overstretched, one can see when the contents are emptied (be that air or water) that it does not regain its original form. If this happens too often or if the distension is too great then its functional ability to move the feed onwards is compromised and can even result in permanent damage or a tear. This form of damage is not a common occurrence however, it does occur more commonly with meat-type breeds which are known to over eat and need feed restriction measures. Once damage has occurred then there is little that can be done to correct the matter.

Intestinal stricture, Impaction and Stasis Tumours and the illness causing them can be involved in crop problems and the underlying cause of stasis and even impaction secondary to a gut/intestinal stasis or intestinal obstruction. Tumours can cause a blockage and obstruction in the intestines which in turn will lead to crop stasis. One common cause of tumours is Mareks disease where (the neurological form) paralysis can cause stasis in the crop and the visceral form of Mareks can cause impaction in the gizzard. There are other forms of oncological (tumour causing) viruses and crop stasis is often associated with them. Intestinal torsion is a rare occurrence but this severe condition will also present with crop stasis where the intestines become knotted or otherwise twisted and causing obstruction. As mentioned earlier, too much fibre can result in an impaction! An acquaintance of mine had this experience with her chicken. The bird had a distended crop and had become very thin during the previous month that she noticed the crop distension... after a time she noticed a distinctly "sour"/yeast-like smell coming from its beak. She tried massaging the distended mass to help pass the contents through but this did not work and the bird continued to get thinner (essentially starving, even though it was eating, as the feed was not getting through to the intestines where digestion of nutrients takes place). When she brought the chicken to the veterinarian it was decided to open the crop (surgically) in order to remove the contents. What they found was a knotted mass of straw, hay and feed. The distension had put such a strain on the musculature of the crop that it had caused tears which had added to the problem and prevented the crop from functioning properly. The veterinarian removed the mass and also part of the damaged (distended and misformed) crop and stitched it back together. Once the bird recovered from the anaesthesia, it received only soft food via a crop tube (this just a few times till the bird was sufficiently recovered to eat on its own) and grain containing feed was avoided at first, as it might damage the healing crop musculature. Thus the bird received only soft feed in the form of a moistened mash/crumble type commercial feed and

bread and a small amount of green- food. Antibiotics were administered to deal with bacterial infection and vitamins to prevent deficiencies. The chicken had a complete recovery and is still with her owner at this time.

Photos on this page courtesy of: Jacqueline Mansveld.

1. Preparation for the surgical anaesthetic. 2. The crop is opened and contents visible. 3. The contents of the crop. 4. The piece of the crop that has been surgically removed (the breed of the chicken is a bantam Cochin / weight 800-1000 grams).

Severe intestinal problems There are several conditions that can impair intestinal health and result in crop stasis... a very common underlying is for instance worms and coccidiosis. Enteral disease / Dysbacteriosis and stricture. This is very common in poultry! Enteral (intestinal) disease/dysbacteriosis causes intestinal stricture and disrupts the digestive process leading to secondary crop stasis. These birds will present with listlessness and will be thin and lose weight (due to the crop stasis not moving the feed through properly) and often have a hard abdomen. A hen we had here presented with a soft yeasty smelling mass in her crop. In this case instead of concentrating on the mass in the crop, it is crucial to treat the underlying cause of it which in this case (determined after the bird died through necropsy) the entire intestine was affected by enteral disease which in turn had caused the crop stasis problem and the contents of the crop to fester and become infected with a secondary infection. Left: The crop is often full during and at the end of the day and should normally be empty when the bird starts its day in the morning.

Fungal Infections of the Crop Fungal infections of the crop are commonly due to Candida Albicans (a type of ‘yeast’). This is often secondary to another (primary) condition or illness in the bird and is often a result of enteral disease, immune incompetency or stagnant bacterial infested water source and unhygienic living conditions. All of these are common causes of Candida Albicans. The crop will often be affected and the Candida will spread to this area and will present with a so called pseudomembrane of caseous material, which you can sometimes see as plaques inside the beak. The bird presents as very ill and listless with little appetite. This condition requires an antifungal medication and you will need the help of your veterinarian to obtain the correct one.

Soft / Mushy Crop When the crop contents fail to empty or remain too long in the crop, for whatever reason, the contents will fester and "yeast" and make your bird ill. This presents with an unpleasant smell that is quite noticeable from the beak and due to the ‘sour’ smell the condition is commonly called ‘Sour Crop’ and is quite often due to Candida Albicans (see above). In order to help your chicken you must have a strong stomach if you are, like so many, sensitive to odours because this condition can produce an extremely unpleasant one! There are many underlying causes for "sour crop" and you may need to consult your veterinarian if your initial efforts to resolve the problem are unsuccessful. Measures you can take yourself to try and resolve the problem: - Increase fluid intake: Often you will need to assist the bird when it refuses to drink and you can accomplish this through employing the use of a syringe (without a needle!): gently open the beak of the bird and travelling along the base of the tongue towards the throat and slowly empty the contents of the syringe. IMPORTANT: Right behind the tongue you will see a small hole and that is the air pipe (trachea) and you must ensure that no fluid flows down this hole! Nothing but air should enter that hole! If you are inexperienced and unsure GET HELP as a mistake here has severe consequences! - Massage the Crop: Once you have introduced fluid into the crop, massage it. Hold the bird upside down as you do this so the contents will flow out and not into the bird as you attempt to massage the contents out. Your bird will often become short of breath and you need to watch for this and if necessary upright the bird and let it recover a bit before continuing. When this is unsuccessful, then you need to stop and get veterinary help and not repeat the procedure continuously as there may be a partial obstruction or impaction in the crop impeding the success of this manoeuvre. Your veterinarian will then choose to proceed with a (tubal) flush and emptying of the crop or if there is an impaction or increment choose to open the crop up and deal with the problem surgically. An antifungal medication is often needed. If you are successful at emptying the crop then I have read that giving a live culture yogurt and adding apple cider vinegar to the water (acidifier) can be very helpful.

Right: This Leghorn hen was thought to be egg-bound, but upon further inspect- tion she had a hard crop.

Hard Crop Crop contents can feel very hard. Sometimes this is due to a knotted mass which may involve the entire contents of the crop. Such a mass can sometimes be found in an extremely high position which one would not normally associate as being the crop. I had a chicken once with a hard crop that presented in a penguin stance and I thought at first she was egg-bound. Upon further inspection I found a hard mass very high up in the crop. The matter was resolved with lots of water and massaging the mass until the crop emptied. Massage without the addition of water has little use. Water... LOTS of water when massaging a hard crop! I also held the bird upside down but there was nothing coming out so I massaged the crop a couple times a day adding extra fluids to it until it finally emptied. When water does not seem to help you can also add a bit of oil, but be warned that even the slightest bit of oil in the air pipe has lethal consequences (>your bird will die). I would suggest you give the oil in the evening and massage it in and then again in the morning.

Photo on the right: Pauline van Schaik.

General Considerations The most important consideration when dealing with crop problems (be it a hard or a soft crop) is (temporarily) withholding feed. Giving feed into a crop which is not functioning and where it is simply going to sit and fester is not going to help your bird, as the nutrients in the feed are not going to be able to be absorbed as long as it remains in the crop. The addition of water is crucial but do not allow your bird to gorge on the water to such an extent that the amount is going to distend and damage the crop. Once the crop has emptied, then slowly and give your bird small amounts of feed with sufficient grains (when there has been no surgery), a granular type of feed rather that a mash or crumble and then slowly proceed to giving more quantity as you check to ensure the crop is moving the contents through.

In Conclusion A crop problem can indicate many underlying conditions or it may be in and of itself a primary problem... it is often difficult to know exactly what has caused it. In any case, "prevention is better than cure" and monitoring the crop, providing a well rounded diet, clean environment and being alert to fibrous materials (especially long strands of grass, hay and straw) will go a long way in preventing problems.

Crop problems do not neces- sarily mean a death sentence to your birds when they are dealt with in the correct man- ner and in a timely fashion. When your own efforts fail to help then don't delay to seek the help of your veterinarian.

Left: As you can see , a full recovery can be seen here with the (broody) little Cochin! Photo: Jaqueline Mansfeld.