Crop Infections in Birds

By Gregory Rich, DVM; Rick Axelson, DVM

Crop infections in pet birds are not as common as they were years ago. They do still occur, however, and they occur primarily in baby birds that are being syringe- or spoon-fed a formula-based diet. While not usually fatal if treated early, crop infections can be serious and may cause problems with appetite and/or digestion.

What is the crop?

The crop (also known as the ingluvies) is a muscular pouch located on the front of a bird's neck, above the top of the chest or sternum. It is an enlargement of the esophagus and serves as a storage place for food. While present in most pet birds, not all birds have a crop. Adult birds produce crop milk from the crop. Crop milk is a secretion of the cells lining the crop, and is used to feed newly hatched birds.

What are some of the causes of crop infections?

The crop, being part of the digestive tract, can become infected by many of the same things that infect other areas of the gastrointestinal tract. ‘Sour crop’ is a term used to denote any infection in the crop. Infection islows or stops the digestive waves of the crop, causing the food contents in the crop to become sour.

"Sour crop is a term used to denote any infection in the crop."

Crop infections can be caused by bacteria or yeast, especially Candida species. Trichomonas, a protozoal organism, causes crop infections that may be difficult to diagnose; this infection is often treated based on clinical suspicion. Viral diseases, such as Bornavirus and Polyomavirus, can also cause slow crop motility and sour crop.

Other crop problems include crop burns (from over-heating formula for baby birds), crop lacerations (from incorrectly feeding baby birds or from other trauma), and the entrapment of foreign objects.

What are some of the signs of crop infection?

The most common symptoms are a fluid-filled, distended crop and/or regurgitation. The regurgitated material may be food, crop fluid, or both. While other conditions can certainly cause regurgitation in birds, the frequency of crop infection suggests considering crop infection before other, more serious, conditions are investigated. Crops that are distended with fluid and showing no signs of motility need immediate veterinary attention.

How are crop infections diagnosed?

Usually, a procedure called a crop wash or crop aspirate is performed. The veterinarian places a small amount of water into the crop using a feeding tube. Some of the fluid is then suctioned out and tested for infectious organisms. The tests may include direct microscopic examination or cultures of the crop fluid.

If an answer is not determined from these tests, other tests, such as swabbing the crop directly to perform a gram stain (a test that looks for bacteria in the crop), radiographs (x-rays), or a crop biopsy, may be needed. Tests that give basic information about the overall health of the bird, such as blood profiles or specific viral disease testing, may also be recommended.

How are crop infections treated?

Once the correct diagnosis is made, your veterinarian will determine the best course of treatment. Bacterial infections are treated with antibiotics. Yeast infections are treated with an anti-fungal medication. Impactions of the crop, crop burns, lacerations, and entrapment of foreign objects in the crop may require a combination of medical and surgical therapy. Crop infections can be very serious and may require your bird be hospitalized and treated. Veterinary attention will be required to resolve any of the aforementioned crop diseases or problems.

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