samoila ionut/ShutterstockIn November 2020, a Belgian racing pigeon called New Kim sold at auction for £1.44 million. The record price offered a striking insight into the money, competition and international interest surrounding pigeon fancying.The breeding and keeping of pigeons for racing or showing is practised worldwide, with particularly valuable European birds attracting buyers from as far away as China. The UK remains one of the sport’s traditional heartlands.Every January, thousands of fanciers (people who breed birds) travel to Blackpool for the British Homing World Show of the Year. They browse trade stalls, meet friends and admire birds with elaborate head feathers, curled plumage and colours ranging from warm reds to iridescent greens. Among the prize birds, our research team is there for a different purpose: we collect blood samples from the fanciers.Pigeon lungPeople who spend many hours around pigeons can develop a condition commonly called pigeon lung, or bird fancier’s lung. It is a form of hypersensitivity pneumonitis, an immune-related disease in which repeated exposure to certain airborne substances causes inflammation deep inside the lungs.The triggers are proteins found in bird droppings, feathers and bloom, the fine powder coating a pigeon’s feathers. These proteins can become part of the dust circulating inside a loft, where the birds are kept, and are then inhaled.Most fanciers never develop the disease. In susceptible people, however, the immune system reacts to the proteins and causes inflammation around the lungs’ tiny air sacs. Symptoms can include coughing, breathlessness, fever and tiredness after spending time with birds.Repeated inflammation can lead to fibrosis – permanent scarring of the lung tissue. This makes the lungs stiffer and reduces their ability to transfer oxygen into the blood. In the most serious cases this can eventually be fatal. Research suggests that pigeon breeders have an increased risk of hypersensitivity pneumonitis and other interstitial lung diseases, an umbrella term for conditions that inflame or scar the tissue surrounding the air sacs. Read more: As the temperature rises, so do the risks for people living with interstitial lung disease Reducing or avoiding exposure is central to treatment. For a fancier, however, complete avoidance may mean giving away birds to which they have devoted much of their life. Some patients also need medicines to reduce inflammation or slow progressive scarring.There is no single test that confirms pigeon lung. Doctors usually consider symptoms, exposure history, breathing tests, blood tests and lung scans. Blood tests can show whether the immune system has reacted to pigeon proteins, but this indicates exposure rather than proving disease.Some fanciers tell us that they have been advised to give up their birds before receiving a thorough investigation. Others describe pigeon fancying being dismissed by their doctors as a “silly hobby”. Such experiences can damage trust. Some fanciers become reluctant to tell healthcare professionals that they keep pigeons, while others delay seeking medical advice.More than four decades ago, Dr Phil Lynch, a GP and pigeon fancier, and Dr Gavin Boyd, a consultant respiratory physician, established a research programme that developed into the British Pigeon Fanciers Medical Research Trust. It is supported by donations from the pigeon-fancying community.Since 2019, our team of researchers, doctors and medical students has worked with the trust at pigeon shows as part of the British Pigeon Fanciers Genetics of Interstitial Lung Disease study.Participants answer questions about their health, work, smoking history and time spent with their birds. We also use breathing tests. Spirometry measures how much air a person can forcefully breathe out and how quickly, giving us a measure of general lung health. Oscillometry uses gentle pressure waves to assess how easily air moves through the lungs and airways allowing us to identify those who have stiffer, and potentially scarred, lungs.Blood samples allow us to study participants’ DNA, antibodies produced against pigeon proteins, and biological markers linked to inflammation. By comparing people who remain healthy with those who develop symptoms or lung abnormalities, we hope to discover why some fanciers become ill while others do not.This could help researchers identify people at greater risk, diagnose the disease earlier and find biological processes that might become targets for treatment.The research could also help people beyond the pigeon-fancying community. Pigeon lung belongs to a wider group of diseases caused by inhaling substances encountered at work, at home or during hobbies.Farmer’s lung is associated with microorganisms growing in mouldy hay or straw. Hot tub lung is linked to breathing fine droplets of water containing certain environmental bacteria. Other cases can be triggered by mould in buildings, contaminated humidifiers or animal proteins. Read more: Hot tubs are as full of nasty germs as you fear The triggers differ, but some immune responses and processes leading to fibrosis may overlap. Studying people with a clearly identifiable exposure could therefore improve understanding of cases in which the trigger is harder to establish.Our visits also provide opportunities to discuss reducing exposure by improving ventilation, controlling dust and wearing a properly fitted protective mask when disturbing feathers or dried droppings. These measures cannot guarantee prevention, and anyone with persistent coughing or breathlessness still needs medical assessment.More than 500 people have taken part in our research, and many return for repeat tests every year. This allows us to examine how their lung function, exposure and immune responses change over time.The project depends heavily on the pigeon-fancying community. Fanciers have helped to fund the work, shape the research questions and encourage others to participate. The trust built over several decades has also been essential.By working alongside fanciers as research partners, the project can investigate a serious disease while respecting an activity that gives participants friendship, purpose and enjoyment.Richard Allen has received funding from the Medical Research Council. Louise Wain receives funding from Medical Research Council and Wellcome Trust.Mark Spears does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.