Adenovirus infection is a contagious disease of pigeons. Its classic form mainly affects young birds and is often complicated by a bacterial infection with Escherichia coli.
What Causes Adenovirus In Pigeons?
For a long time, the disease was known only in its classic form, now called type I, which mainly affects young pigeons.
Since the 1990s, a second form, type II or necrotising hepatitis, has been reported more often. It can affect pigeons of any age.
Type I spreads easily but is usually not deadly. Young birds can show a range of signs, but most recover within about a week or two.
Type II is more dangerous, and many affected birds die quickly.
How Common is Adenovirus in Pigeons?
The infection has been reported in many places, especially in Europe. Type I is seasonal in many countries, with most cases in spring and early summer, when young birds start training and racing.
Type II can turn up at other times of year, including winter, in both show and racing pigeons.
Transport to races and shows makes things worse, because birds are kept close together and sick birds can easily infect the others.
Causes of Adenoviruses in Pigeons
The virus is shed in droppings, so sharing the same loft, feeders and waterers is the main way it spreads. The virus is thought to be present in many pigeon populations.
Studies suggest that stress and poor hygiene make outbreaks of both types more likely.
In type I, many birds in a loft may fall ill (up to about 80% has been reported), but deaths are usually few. Type II can kill up to about 30% of the birds in an affected loft.
Morbidity is the share of birds that fall ill; mortality is the share that die.
Symptoms
The typical clinical signs that can be seen in sick pigeons are mostly related to their gastrointestinal health.
Vomiting, watery diarrhoea and weight loss are the most noticeable signs of type I.
There is an incubation period that exists between the time the bird has become infected and the moment it starts showing clinical signs.
An important feature of the disease is that it often occurs together with other infections.
The virus damages the gut lining and weakens the bird’s defences, which allows bacteria to cause further problems.
The infection is often named ‘Adeno-coli syndrome’ because Escherichia coli is a bacterium that is involved in the entire process, too.
Some other symptoms that can be noticed in infected pigeons are the following:
- Loss of appetite
- Ruffled feathers
- Vomiting
- Watery, brown, or green droppings
- A lack of reaction to sounds or birds nearby
- Severe weakening
Without treatment of secondary infections, some birds may die within about two weeks of showing the first signs.
In type II, the virus itself causes necrotising hepatitis (death of liver tissue).
Birds with type II often die within 24 to 48 hours, and some die without showing any signs.
In older birds, other bacteria such as Staphylococcus or Streptococcus species may also cause secondary infections.
Diagnosis
Isolating the pathogen can be quite complicated, and a differential diagnosis must be performed by the veterinarian to make sure that the pigeons are not, in fact, suffering from other diseases (such as Salmonellosis, Hexamitiasis, or Paramyxovirus).
In some countries, such as Germany or Belgium, where there is a specific seasonality of Adenovirus in pigeons, a diagnosis can be based on the clinical findings.
Transmission electron microscopy (TEM) can confirm the virus, but it is usually available only at veterinary schools and research laboratories.
Classic histopathologic examinations can also be performed, and in this case, the diagnosis is based on the particular modifications inside the cells of the liver.
Multiple hepatocellular necrosis sites are revealed using this method, and some smears also reveal the presence of basophilic bodies inside the hepatocytes.
PCR tests for pigeon adenovirus are also offered by some laboratories.
Can Adenovirus in Pigeons Be Treated?
There is no specific antiviral treatment, but supportive care and treatment of secondary infections can help many birds recover.
In pigeons, adenoviruses rarely act alone.
Other factors and organisms usually contribute to the gut symptoms that sometimes lead to death.
In type I, deaths are often caused by septicaemia from a secondary E. coli infection rather than by the virus itself.
Type II is much more virulent, which is why it can kill adult pigeons within 24 to 48 hours of the first signs.
For type I, birds often improve when a vet prescribes antibiotics for secondary bacterial infections such as E. coli.
Only use medicines prescribed by a vet, as some drugs once used in pigeons are now banned or restricted in many countries.
Because adenovirus often occurs together with parasites, some birds may also need treatment for these, based on tests.
Parasites damage the gut lining, which may make it easier for the virus to take hold.
A bird can have coccidiosis, adenovirus and an E. coli infection all at once, and this combination is often fatal.
Survival Expectations & Recovery
Both depend largely on the general health of the birds.
If pigeons already have other infections or weak immunity, losses in the loft are likely to be higher than usual.
Type I is less virulent than type II, even though the young pigeons it affects tend to show more obvious signs.
Deaths in this age group are usually low.
Type II is more aggressive and causes acute disease in birds of any age. An earlier bacterial or parasitic infection may also be present without the fancier noticing.
Some fanciers give routine preventive antibiotics, but vets increasingly advise against this.
Routine use encourages antibiotic resistance, so it is better to treat based on a diagnosis.
Even though Adenoviruses are present in many wild pigeons, too, they might not affect ornamental or racing ones if they are kept in good conditions, are fed the right type of food, and are not exposed to too many stressful conditions.
Stress seems to be an important factor, which fits with the seasonal pattern of the disease.
In the racing season, young racing pigeons tend to develop adeno-coli syndrome. Cold weather may also stress birds and make them more vulnerable.
Prevention Of Adenovirus
Separating the birds from one another, especially those that are showing any clinical signs, is necessary to limit the spread of the virus and bacteria as much as possible.
However, this might not be effective every time, especially since, given the incubation period, by the time they start showing symptoms, the birds might have already infected the rest of the flock.
Sick birds should not be raced: their performance will drop and they can infect other birds.
Unfortunately, there is no completely effective way of preventing Adenovirus in pigeons. Pigeon aficionados are advised to practice excellent hygiene.
New birds should be quarantined for at least two weeks before joining the flock, to check that they are not carrying diseases such as adenovirus.
Good nutrition, warm and dry lofts and low stress help prevent illness in general.
Ask your vet before giving any supplements or medicines routinely.
While a vaccine against Escherichia coli does exist, it mostly tends to be used on chickens and turkeys.
At the time of writing, there is no widely available adenovirus vaccine for pigeons.
Ask your vet whether any vaccine or other preventive product is licensed for pigeons in your country.
Discussion
There is still no specific treatment for adenovirus in pigeons, for type I or type II.
This means the best thing you can do as a fancier is keep the loft in excellent condition.
Birds shed the virus and secondary bacteria and parasites in their droppings and other secretions, so regular cleaning is very important.
Also, pigeons can accidentally carry the pathogens on their feet, feathers, beaks, or skin, especially if they tend to hang around wet areas (around their waterers).
Preventing and treating this disease might be possible in some situations, so make sure you communicate with your veterinarian if you have any concerns in this sense.
Treatment usually combines medicines for secondary infections and parasites with supportive care.
Your vet may also suggest products that support the liver and gut flora and help with dehydration.
Some disinfectants are made for use in drinking water and may help limit spread in the flock; use only products intended for pigeons and follow the label.
This guide is general information. If a bird is injured or seriously ill, contact an avian vet or a wildlife rescue as soon as you can.
Sources:
- Necrotizing Hepatitis in a Domestic Pigeon (Columba livia) (opens in new tab)
- Adenovirus infections in pigeons: A review (opens in new tab)
- Update on “Young pigeon disease (YPD) syndrome”
Last updated 30 October 2026 · Health