Diarrhea occurs when the intestinal tract is unable to absorb fluid or when the cells lining the intestines secrete excessive amounts of fluid. Many factors can alter the intestinal tract's ability to absorb or secrete fluids properly. For example, if food is not properly digested, it will tend to pull fluid into the intestines. Or, if the lining of the intestinal tract is irritated by a toxin, infection or irritation, cellular changes will cause an increase in secretion of fluid into the intestines. Bacterial infection. Bacterial infections may come from other birds, from an overgrowth of dangerous bacteria on dirty food or water bowls, or spoiled foods. Often, small amounts of potentially dangerous bacteria live in the intestinal tract without causing harm. This population of bacteria can overgrow and cause disease if the bird's immune system is not functioning properly, as may occur during times of stress. An overgrowth of harmful bacteria may also occur when antibiotics are used improperly.
Peristaltic waves, which are rhythmic contractions of the intestinal tract that serve to push digested food forward, occur at regular controlled intervals in normal birds. In some birds with diarrhea, these waves lack coordination, so that food moves through the intestinal tract too quickly. This results in an increase in frequency of defecation, and an increase in the liquid content since fluid does not have a chance to be absorbed.
Birds may normally have an occasional dropping in which the fecal component is not well formed. This can occur due to excitement or stress, or be due to sudden changes in the diet. For example, if a bird is fed a large quantity of fruits (and sometimes vegetables) and fruits are not normally a regular part of his diet, he may temporarily develop a loose appearing dropping. This is due in part to the increase in fluid content of the diet, but a similar type of temporary diarrhea may occur with any sudden diet change. This should resolve after all of the fruit or new food is digested, and should not last more than 12 hours after new food has been removed from the diet. If the diarrhea persists, or if the bird develops any other symptoms such as vomiting, lethargy or a change in appetite, veterinary attention is required immediately.
The color of the feces can also change due to alterations in the diet. For example, if birds are fed heavily pigmented foods, such as berries, tomato products or colored pellets, the stool may turn the color of the food. If the stool ever appears to be a very dark green-black color, however, your veterinarian should be notified immediately, since this color may be caused by digested blood (melena).
There are many causes of diarrhea in birds. The cause may be very simple, such as a dietary change or yeast overgrowth, or may be due to a number of complex disease processes. Many contagious diseases cause diarrhea, so it is important to inform your veterinarian of any potential contact – direct or indirect – with other birds.
Viral infection. Several different avian viruses may cause diarrhea. In most cases, diarrhea is only one of several symptoms. Viruses can be transmitted by direct exposure to another bird, shared food or water dishes, or on your hands or clothing, depending on the type of virus.
Yeast infection. Candida is a type of yeast that normally lives in small quantities in the intestinal tract. Stress or antibiotic use can also cause an overgrowth of Candida, leading to diarrhea.
Parasites. One of the more common intestinal parasites of pet birds is Giardia, a microscopic organism that lives in the small intestine. Giardia can cause severe diarrhea and weight loss, and is potentially transmissible to people. Other microscopic parasites, such as heximita and coccida are less common causes of diarrhea in pet birds. Intestinal worms, such as roundworms and tapeworms, may occasionally be a cause. These worms are specific to avian species and do not cause disease in mammals.
Cloacal papillomas. Papillomas are wart-like structures. They appear most commonly in the cloaca, but may occur anywhere along the gastrointestinal tract. Papillomas may be a cause of diarrhea. There is also a higher incidence of gastrointestinal tract cancer in birds with cloacal papillomas.
Obstruction. Tumors or foreign objects may block the intestinal tract. Occasionally, an intestinal intussusception (telescoping of one part of the intestinal tract into another) may cause diarrhea initially, then a lack of feces later in the course of disease.
Antibiotic use. Birds may develop diarrhea following treatment with antibiotics due to changes in the normal bacteria found in the intestinal tract.
Other Causes Cancer
Toxins, such as heavy metals and plant toxins
Stress-induced, such as changes in environment
Metabolic disorders like liver or kidney disease, diabetes mellitus
Dietary causes like diet changes, eating spoiled food, dietary intolerance
Maldigestion, such as liver disease, inflammation or infection in the pancreas