CONDITION
Eosinophilic Bronchopneumopathy
Eosinophilic bronchopneumopathy is a condition in which a particular type of white blood cell—the eosinophil—accumulates in the airways and lung tissue, causing inflammation. These cells are part of the immune system and typically respond to parasites or allergens, but in this condition they gather in the lungs without an obvious trigger, leading to airway narrowing and difficulty breathing. Owners often first notice persistent coughing, increased breathing effort, or wheezing that doesn't resolve with rest. Some animals may show reduced tolerance for exercise or appear to tire more easily during walks. The signs can develop gradually over weeks or appear more suddenly, and in some cases they may seem to improve and then return. This page explores the breathing and behaviour changes that can occur, what is understood about the underlying inflammatory process, the investigations that help distinguish this condition from other causes of respiratory signs, and the treatment approaches that veterinary teams may consider.
Why this matters now
Eosinophilic bronchopneumopathy tends to be recognised in young to middle-aged cats, often between two and eight years of age, though it can appear outside this range. Siamese and related breeds appear to be represented more frequently in reported cases, suggesting a possible genetic component. There is no strong seasonal pattern, and the condition can emerge in animals living indoors or outdoors, in urban or rural settings.
The condition may begin with subtle, intermittent signs that an owner might initially attribute to a minor respiratory irritation. In some animals the signs remain mild and stable for months, whilst in others they progress over weeks to more pronounced breathing difficulty. Episodes of worsening may be separated by periods of apparent improvement, creating a pattern that can make it difficult to judge the trajectory without careful observation over time.
Signals & patterns
Early signals
Dry, recurrent cough
A cough that appears without obvious cause and persists beyond a few days, often worse at night or after activity. The cough may sound harsh or hacking, and typically does not produce visible discharge.
Increased breathing effort at rest
Breathing that appears more deliberate or effortful when the animal is lying quietly, sometimes with visible movement of the chest or flanks. This may be subtle at first and easier to notice when the animal is settled in familiar surroundings.
Reduced stamina during activity
A previously active cat may begin to disengage from play sooner or show less interest in exploring. Walks that were once routine may prompt the animal to pause or seek rest earlier than usual.
Wheezing or audible breathing
A high-pitched or whistling sound that can be heard during breathing, particularly on exhalation. This may be intermittent and more noticeable in quiet environments or after mild exertion.
Later signals
Open-mouth breathing
Breathing through an open mouth whilst at rest or after minimal activity, a pattern that is uncommon in healthy cats and suggests significant airway compromise. The animal may appear anxious or restless during these episodes.
Postural changes during breathing
The animal may adopt positions that seem designed to ease breathing, such as sitting with the neck extended or standing with elbows turned outward. These postures can reflect an attempt to maximise airflow.
Weight loss or reduced appetite
Chronic breathing difficulty can increase the energy cost of breathing and reduce interest in food, leading to gradual weight loss. This may be accompanied by a quieter demeanour or withdrawal from social interaction.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
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