Papillomatosis in Psittacine Birds
Papillomatosis is the term used to define the occurrence of proliferative, wart-like masses on the surface of the cloaca or anywhere along the alimentary tract, such as the oral cavity, crop, proventriculus and intestines, in psittacine birds.
While the cause of papillomatosis remains unconfirmed, it is probably caused by a virus. Until ongoing research is completed, this disease should be differentiated from papillomas, or warts, which are known to be caused by papillomaviruses.
Some research demonstrated that the papillomavirus may be involved. Other research indicates herpesvirus. While the cause of papillomatosis is only speculative, both papillomaviruses and herpesviruses are generally host-specific. The representatives of these viruses that are known to infect birds have not been shown to infect humans or to cause disease in unrelated species of birds following natural exposure.
The incubation period of development of papillomatosis remains unconfirmed. Field observations suggest it can take months or years for detectable lesions to occur.
Papillomatosis of the cloaca has been linked to some types of liver and pancreatic cancers.
What to Watch For
- Difficulty swallowing
- Straining to pass excrement from the cloaca
- Putrid smelling or blood tinged excrement
- Bad breath
- Difficulty breathing or wheezing
- Accumulation of excrement around the vent
- Chronic weight loss
- Loss of appetite
- Yellowish or greenish discoloration of the urates and urine
Diagnosing papillomatosis can be challenging. Microscopic examination of tissue collected from the mass is necessary to confirm the diagnosis. Addtional test may include:
- Complete blood count (CBC)
- Blood chemistries
- Radiographs (X-rays)
- DNA probe-based test (PCR) on choanal and cloacal swab
Treatment for papillomatosis is usually unnecessary unless the growth is interfering with swallowing, breathing or defecating.
When necessary, papillomatous growths can be removed with surgery or, in some cases, chemical cauterization. Fluids, supportive nutrition and antimicrobials may be needed in birds with severe chronic lesions, secondary problems or after surgical removal of a mass. High quality diets rich in Vitamin A are also recommended.
Unfortunately, there has been no successful treatment reported for the liver and pancreatic cancers associated with papillomatosis.
Home Care and Prevention
Keep birds with lesions and those to which they have been exposed separated from other birds. On a daily basis, monitor fecal output to ensure proper food consumption and digestion and monitor your bird's weight daily.
The most important prevenative measure is to keep your bird out of direct or indirect contact with other birds. If you decide to add a new bird to your family, he should be quarantined for at least 90 days and be examined by an avian veterinarian at the beginning and end of quarantine. Be aware that there is currently no proven method for documenting that a bird does not have papillomatosis.
There is currently no vaccine available to help prevent the unrestricted spread of papillomatosis in birds.
Based on the clinical and microscopic changes associated with papillomatosis, a virus has always been considered its most likely cause. Recent research findings have suggested that pieces of the genetic material (DNA) from a papillomavirus can be detected in cells from some birds with papillomatosis. Other research has shown some papillomatous lesions contain herpesvirus-like particles or pieces of Pacheco's disease virus (an avian herpesvirus). Many affected birds also have antibodies to Pacheco's disease virus. It is most likely that papillomatosis is caused by a papillomavirus and that Pacheco's disease virus co-infects the damaged cells.
If papillomatosis is caused by a papillomavirus, it is likely that it will behave similarly to papillomaviruses in other species. Once the papillomavirus takes over a cell, it causes the cell to undergo cancerous changes resulting in a thickening of the skin and development of a mass. In humans, some papillomaviruses have been shown to be associated with cancerous changes in the mouth, alimentary tract and reproductive tract.
The factors associated with development of papillomatosis are unconfirmed. If it is proven to be infectious, which is highly likely, it is probable that birds are exposed through direct contact with an infected bird or through contact with a contaminated surface (perch, enclosure, table, food bowls, etc). If a papillomavirus is involved, these viruses are considered to be relatively stable when outside of the host. If a herpesvirus is involved, these viruses tend to be relatively unstable when outside of the host. Cool, moist conditions and freezing will preserve the infectivity of most viruses.
Clinical signs in birds with papillomatosis generally occur when the mass interferes with swallowing, digestion or defecation. This disease should be suspected in birds that are straining to defecate, have putrid smelling excrement, chronic bad breath, recurrent gastrointestinal problems, cloacal prolapse or blood-tinged excrement. Internal papillomatosis is usually associated with chronic weight loss and regurgitation and can mimic the signs of proventricular dilatation disease.
While the data varies among studies, papillomatosis seems particularly common in macaws and hawk-headed parrots. However, the disease has been diagnosed in many other psittacine birds, including Amazon parrots, conures, cockatiels and African grey parrots.
The tendency of birds with papillomatosis to develop cancer of the pancreas or liver would suggest that cloacal or oral lesions may be caused by a virus that can transform infected cells.
A thorough physical examination with detailed observation of the oral and cloacal mucosa is the most likely way to detect suspicious lesions. The cloaca should be gently turned outward using a gloved finger, moistened cotton-tipped applicator or speculum to facilitate the examination. Papillomatosis should be suspected when cauliflower-like growths are visible.
Papillomatous changes may occur in the oral cavity or esophagus in birds that do or do not have detectable lesions in the cloaca. The fusing, raised bumps characteristic of papillomatosis can be red, pink or white and have a tendency to bleed if damaged. Coating the surface of any suspect lesion with 5 percent acetic acid solution will help identify papillomatous changes. The abnormal tissue will turn white, while the normal mucosa remains pink. Microscopic examination of tissue samples from suspect lesions is required to confirm a diagnosis.
Many internal lesions are not recognized until autopsy. Filling defects (indicating that a mass is present in the lumen of the alimentary tract) may be detected by contrast radiography (Barium series) performed on birds with suspicious clinical signs such as chronic regurgitation or weight loss.
Endoscopy is necessary to identify and obtain diagnostic biopsies of suspect papillomatous lesions in the esophagus, proventriculus or high in the cloaca. A liver biopsy may be helpful in confirming cancerous changes in birds that have a history of cloacal papillomatosis and clinical changes suggestive of liver disease.
Other tests include:
- CBC and blood chemistry. Most birds with papillomatous lesions in the gastrointestinal tract do not have detectable changes in the complete blood count (CBC) or blood chemistry. However, the white blood cell count may be elevated in birds with internal lesions that are ulcerated and secondarily infected with bacteria or fungi.
- Viral testing. Testing for antibodies to Pacheco's disease virus or using viral specific DNA probes to determine if a bird is shedding pieces of genetic material (DNA) from this virus may be helpful.
- Currently, there is no test that can be used to confirm that a bird does not have papillomatosis.
Generally, papillomatous lesions that are not causing specific problems can remain untreated. Untreated birds should be carefully and frequently monitored for changes that would suggest more aggressive treatment is necessary. Oral papillomas are frequently localized, easy to remove and may not reoccur after removal. In contrast, cloacal papillomas are typically diffuse, difficult to remove completely and frequently reoccur after treatment. Attempted removal may involve various surgical techniques (lasers, radiosurgery and ligation) or chemical cautery.
When any technique is used to remove growths mechanically from the cloaca, care should be exercised to prevent excessive tissue damage that may result in severe scarring and reduction in the size of the cloacal lumen. Scarring can result in incontinence, reproductive failure or blockage of the ureters or colon. None of the proposed therapies is consistently effective in all cases, and papillomatous lesions often recur following what may appear to be a successful treatment regime.
Malnutrition and vitamin A deficiencies have been suggested to potentiate papillomatosis. If true, then providing supplemental vitamin A would be indicated.
Optimal treatment for your companion bird requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your bird does not rapidly improve.
Make certain you administer all prescribed medications at the appropriate time intervals. Contact your veterinarian immediately if you are having difficulties treating your bird as prescribed. If you are having problems, it may be best to hospitalize your bird to assure that a proper course of treatment is administered.
Any bird suspected of having papillomatosis, that has been exposed to birds with papillomatosis or that is being treated for papillomatosis should be isolated from other birds to prevent transmission. The common practice of placing a hospital or "sick" room in the same building or airspace with a psittacine nursery is contrary to good medical practices.
If this disease is caused by a virus, which is likely, then with most viruses organic debris such as blood, soil, nesting material or feces would be expected to protect the causative agent from disinfectants that do not contain detergents.
Caretakers should always wear a dust mask when handling the waste of birds. To reduce dust, use a misting bottle filled with disinfectant to moisten excrement and feather debris before handling.