Vomiting in Birds
Dr. Barbara Oglesbee
The upper gastrointestinal tract of pet birds has several unique features. Diverticulum. After being swallowed, food moves into a diverticulum of the esophagus called the crop. The function of the crop is to moisten, soften and store food.
Proventriculus. Food then moves from the crop into the first stomach, called the proventriculus. The proventriculus contains glands that secrete enzymes and acid to begin the chemical digestion of the ingested food.
Ventriculus. Once these chemicals have been added, the food then moves into the second stomach, the ventriculus. The ventriculus contains two opposing sets of muscles, which grind and macerate the food.
Peristalsis. Movement of food from the crop to the proventriculus to the ventriculus is dependent on highly coordinated contractions called peristalsis.
Vomiting should be differentiated from regurgitation. Regurgitation can be a normal behavior in a healthy bird, whereas vomiting is always abnormal. Vomiting occurs when food from the proventriculus or ventriculus is forcefully expelled through the mouth. This food is digested or partially digested and has an acidic liquid. Food that is regurgitated originates from the crop and is undigested.
Vomiting can be differentiated from regurgitation by observing both the behavior of the bird, and the appearance of the expelled food. Birds that are regurgitating will consciously and vigorously bob their head, and then bring the softened, undigested food into the mouth. This food may then be re-ingested, or dropped from the mouth.
Regurgitation is normal behavior during nesting and courtship. Birds often regurgitate food from their crops to feed to their mate or to feed to their offspring while in the nest. Pet birds often attempt to feed regurgitated food to their owners, cage mates, toys or shiny objects such as mirrors or bells. If regurgitation is a behavior not caused by disease, your bird should always be directing the behavior towards someone or something. If he is regurgitating food in the absence of such stimulus, or regurgitating excessively, seek veterinary attention.
In contrast, birds that are vomiting will suddenly bring digested food containing an acidic liquid from the proventriculus or ventriculus into their mouth. They will then rapidly spit out the fluid, usually by flinging their head from side to side. Often, the vomitus will spray out onto the bird's head and around the cage. Sometimes, a bird vomits stomach contents into the crop, and then regurgitates vomitus. Nevertheless, as soon as the foul-tasting stomach contents enter the mouth, it is rapidly spit out. Vomiting, unlike regurgitation, is not directed toward an object, and the bird does not re-ingest it.
Vomiting is always abnormal, and your veterinarian should be consulted. Birds that are vomiting and have other symptoms, such as diarrhea, lack of appetite or lethargy require immediate attention.
There are many causes of vomiting in birds. Vomiting can be caused by diseases of the digestive tract or can occur due to toxicities, disease of the nervous system or metabolic diseases. There are many contagious diseases that cause vomiting, so it is important to inform your veterinarian of any potential contact – direct or indirect – with other birds. Possible causes of vomiting in birds include:
Obstruction. Ingested foreign objects may block the intestinal tract. Psittacine birds have powerful beaks, and a strong instinct to chew. Objects that commonly obstruct the intestinal tract include string toys, bark or wood shavings, and pieces of rubber toys.
Toxins. Heavy metals, plants and cigarettes are commonly ingested. Most plants and cigarettes cause vomiting by irritating the intestinal tract. Heavy metal toxicity, caused by ingestion of objects containing lead or zinc, is one of the most common diseases seen in pet birds. Not all birds with heavy metal toxicosis vomit, and most have other symptoms, especially neurologic signs.
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.
Viral infection. Several different avian viruses may cause vomiting. In most cases, vomiting will be 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 vomiting.
Parasites. Trichomonas is a common cause of vomiting in small psittacine birds, especially budgerigars. Other intestinal parasites such as Giardia, heximita, coccida, roundworms and tapeworms, may occasionally be a cause.
Antibiotics. Some antibiotics and antifungal medications may temporarily cause vomiting. Usually, this will stop once administration of the medication is discontinued.
Cancer. Papillomas (wart-like structures) or cancer may occur anywhere along the gastrointestinal tract.
Metabolic disorders. Liver disease, diabetes mellitus, renal disease can all result in vomiting.
Neurologic disorders. Vomiting may be triggered by infection or inflammation of the brain, or by motion sickness.
Dietary. Diet changes, eating spoiled food, dietary intolerance can all cause vomiting.