Disorders Affecting Multiple Body Systems of Pet Birds

Polyomavirus infection was first identified in budgerigars (budgies) and later in other parrots and finches. Birds of all ages can be affected, but nestlings and juvenile birds are the most vulnerable. Although the virus can be passed from females to offspring while they are still within eggs, most infections spread after hatching through direct contact with an infected bird, feather dust, or infected droppings. 

Birds infected by polyomavirus often quickly develop poor appetite, diarrhea, and weakness. The virus might also cause bruising under the skin and in muscles, and it can damage the heart, liver, and kidneys.

Polyomavirus infection in birds is usually fatal, and death often occurs within 24–48 hours. Survivors might have abnormal feathers, heart disease, and liver damage later in life. Adult birds can carry the virus and spread it without appearing sick. The infection rate in adult parrots and budgies is believed to be high.

There is no treatment for birds infected by polyomavirus. Control of the virus involves testing by a veterinarian, isolating infected birds, and vaccination. During outbreaks of infection, strict hygiene, including disinfection of feeding utensils and cages, plus vaccination, are used.

The risk of polyomavirus infection can be decreased by following strict cleanliness, limiting visitors’ contact with chicks, and quarantining new birds. Regular veterinary screening is recommended to check birds for polyomavirus infection.

A vaccine against polyomavirus is available and is given in two doses. Vaccination is usually not recommended for single pet birds that are not exposed to other birds. It is intended for birds that travel or regularly come into contact with other birds.

The first polyomavirus vaccine dose can be given when birds are 4 weeks old. Older birds receive two doses 2–4 weeks apart, then yearly boosters. Both infected and uninfected adults and juveniles can be vaccinated.

Pacheco disease is a highly contagious, rapidly developing herpesvirus infection in parrots. It is closely linked to stress, which can cause birds that appear healthy but carry the virus to shed it in their droppings and infect other birds.

The virus that causes Pacheco disease spreads through coming into direct contact, breathing in feather dust and body fluids, and ingesting contaminated food or water. Macaws, Amazon parrots, monk parakeets, and conures are commonly involved in outbreaks. Parrots native to Asia, Africa, or Australia are less likely to be carriers or to get sick.

Birds often show no symptoms of Pacheco disease until shortly before death. These birds usually appear well, with normal weight and appetite. Symptoms, if seen, include fluffed feathers, low energy, and watery droppings. Most affected birds do not recover.

Rapid diagnosis and isolation of infected birds is essential to prevent the spread of Pacheco disease.

Some herpesviruses can cause wartlike growths (called papillomas) on the feet of cockatoos and loss of skin color on the feet of some macaws.

Internal growths (a condition called papillomatosis) in green‑wing macaws and Amazon parrots are caused by a herpesvirus related to the one that causes Pacheco disease (see above).

Amazon tracheitis, a rare infection of the trachea (main breathing airway), is also caused by a herpesvirus.

Poxvirus infections occur most often in canaries, pigeons, and some wild birds, and occasionally in parrots.

Birds can show one of three clinical forms of poxvirus infection:

• The most common form is dry pox, which is a skin infection with nodules, small abscesses (pus pockets), or scabs on bare skin areas such as the face, around the eyes and mouth, and on legs and feet.

• The second form, called wet pox, might follow or occur without the skin form. It affects the mouth, throat, upper airways, and esophagus, often causing eye swelling and discharge.

• The third, most severe, form causes rapid development of low energy, bluish discoloration of skin, loss of appetite, and sudden death.

Birds with poxvirus infections are usually treated with vitamin A, antibiotics, eye ointments, warmth, humidity, careful cleaning of lesions, and good nutrition.

Poxviruses are spread mainly by the bite of mosquitoes or through breaks in the skin. Controlling mosquitoes and housing birds indoors are important measures to protect against infection by poxviruses.

Vaccines exist for canarypox and pigeonpox, but they protect against only those specific diseases.

Mycobacteriosis in birds, sometimes called avian tuberculosis, is caused by several species of bacteria. This disease is not the same as tuberculosis in mammals. It occurs most commonly in adult parrots and usually affects the intestines, liver, and digestive system. The disease is lifelong, ongoing, and often fatal. It does not typically cause the same respiratory symptoms that people with tuberculosis develop.

Symptoms of mycobacteriosis in birds include poor appetite, weight loss despite eating, low energy, and diarrhea. Early in infection, there might be no symptoms. Diagnosis is difficult and relies on microscopic analysis of a biopsy of the affected organ to see the bacteria. 

The treatment for mycobacteriosis in birds is difficult and takes a long time, often up to a year. The disease can potentially spread from birds to people, so strict hygiene is essential. You should wash your hands carefully after handling infected birds, and use gloves and other protections to minimize spread.

The risk of spreading mycobacteriosis to people appears low, but those who are very young, elderly, or have impaired immune system function (for example, people receiving chemotherapy) should avoid contact with infected birds.

Psittacosis is caused by infection with the bacterium Chlamydia psittaci. It is a serious disease that can spread from birds to people. The bacteria are present in discharge from the nose and in droppings from sick birds, recovering birds, and carriers (birds that carry the bacteria but are unaffected).

Because of the human health risk, suspected cases of psittacosis in birds must be reported to state health officials in the United States, and there are specific rules for quarantine and treatment of affected birds. 

Some birds, including pigeons, doves, budgies, cockatiels, cockatoos, and many others, are more resistant to infection with psittacosis and can become carriers without obvious illness. Other birds, such as rosellas, lorikeets, mynahs, canaries, and several other parrots, are less resistant.

Symptoms of psittacosis in birds vary by species but typically include ruffled feathers, low energy, labored breathing, eye and nose discharge, lack of appetite, and decreased vocalizing. Lime‑green or yellow droppings, especially with yellow-green urine, are common.

A form of psittacosis that affects the nervous system, which occurs less often, causes tremors, shaking, head twisting, and seizures. This form is most often reported in African grey parrots and cockatoos. Some cockatiels and Neophema parakeets can develop eye problems. The liver and heart also might become inflamed.

Birds diagnosed with psittacosis are treated with prolonged antibiotic therapy. Severely affected birds require intensive care in the hospital, including injectable antibiotics, fluids, warmth, strict cleanliness, and minimal stress.

The focus for preventing psittacosis in birds is to avoid exposure. The bacteria can survive for months in dried droppings, so cleaning and disinfection are crucial. Controlling drafts and using appropriate disinfectants help to decrease spread of the bacteria in dust and feather dander.

Birds that have recovered from psittacosis or are still under treatment can become infected again.

Because psittacosis can infect people, proper hygiene is vital when handling sick birds. You should wear gloves, wash your hands thoroughly after handling these birds, and disinfect cages, feeders, and feeding utensils daily. All new birds should be tested for psittacosis and other infections before being introduced to a household flock. Affected birds should be kept isolated from other birds while undergoing treatment.

Spore-forming bacteria called clostridia can cause several diseases in birds, depending on the species and infection site. Birds become infected by eating spore-contaminated food or water, inhaling spores or bacteria from contaminated dust or surfaces, or through spore contact with open wounds.

A common way that clostridia infect birds is to enter the bird's body at a point of damage to the lining of the cloaca (the saclike compartment inside the bird’s body where the digestive, reproductive, and urinary tracts come together). Birds with prolapse of the cloaca or with wartlike growths inside the cloaca caused by herpesvirus (a condition called papillomatosis) are particularly prone to infection.

Symptoms of clostridial diseases vary by the strain of Clostridium bacteria. Disease‑causing strains produce toxins in the bird's small intestine, leading to rapid weight loss, low energy, decreased appetite, and blood or undigested food in droppings. Toxins can continue to affect the bird even after the bacteria have been treated with antibiotics.

The focus for preventing clostridial disease in birds is to decrease stress and overcrowding, provide good ventilation, and feed the bird a balanced diet. Food should be stored properly to prevent bacterial growth. Bacterial spores can be present in corn, grains, and manufactured foods and can grow into infectious bacteria if food is not stored correctly.

The feces of household dogs and cats can also contain Clostridium bacteria, so it is important to keep birds away from these feces.

Heavy metals like lead and zinc are common in the environment, and it is important to prevent birds’ exposure to them. Birds should not roam unsupervised outside their cages.

If you have a pet bird, your home should be inspected for heavy metal sources, and these should be removed when possible. Metal cages and other objects (such as some bird toys containing metal) are frequent sources. Stainless steel and welded wire made from safe metal alloys are preferred for use in cages. Toys, cage clips, and other hardware should not contain lead or zinc.

Lead and zinc are the most common heavy metals that poison pet birds. Zinc poisoning is now more common because awareness of lead dangers has led to decreased use of lead and more use of galvanized (zinc‑coated) materials in all metal products. Galvanized wire and hardware, often used in homemade cages, can be a major source of zinc poisoning in birds.

Common sources of lead include old paint, stained glass, curtain and fishing weights, and lead solder. Symptoms of heavy metal poisoning in birds include regurgitation, excessive thirst, low energy, and weakness. Lead poisoning can also cause trembling, clenched feet, loss of coordination, excitability, and seizures.

A veterinarian might suspect heavy metal poisoning in your pet bird if typical symptoms are accompanied by x-ray proof of metal in the bird’s stomach. Paint is not visible on x‑rays, so final diagnosis requires blood tests for lead, zinc, or other metals.

Initial treatment for heavy metal poisoning in birds usually includes supportive care, including injection of fluids under the skin, along with injection of drugs (called chelators) that bind metals in the blood and other organs to help remove them from the body. After birds are stabilized, chelators can often be given by mouth at home.

If heavy metal poisoning is treated early and the exposure is not severe, birds often recover quickly. Prevention by removing or avoiding metal sources is essential.

Overheating nonstick cookware and other nonstick-coated items is dangerous to pet birds. Nonstick pans, self‑cleaning ovens, some heat lamps, many air fryers, certain toaster ovens and waffle irons, and some hairdryers can contain coatings that, when overheated, release invisible, odorless gases that can rapidly kill birds that inhale them.

Other home hazards include aerosol sprays (such as some carpet fresheners, cleaning products, and perfumes), plastic fumes from items melted or burned in microwaves, and chemicals from new heating ducts. All of these can also harm birds.

Symptoms of fume poisoning in birds include severe breathing difficulty, neurological effects, and sudden death. Many exposures to dangerous fumes or aerosols kill birds before treatment is possible. If your bird is exposed to such fumes and still alive, move it to fresh air immediately, and take it to a veterinarian at once.

Cage placement is important. Birds should be kept far from all cooking and other potential fume sources and in well‑ventilated areas.

• Also see professional content regarding viral diseases, bacterial diseases, and toxicoses in pet birds.