SYMPTOM

Laboured breathing

Laboured breathing means each breath takes visible effort. Owners may see the belly pushing with each breath, the chest heaving, nostrils flaring, elbows held out from the chest, the head and neck stretched forwards, or reluctance to lie down. Breathing may be noisy or silent, fast and shallow, or slower and deep. In cats, breathing with the mouth open is a particular marker of distress, since cats rarely do this. Brief open-mouth breathing after hard play or a stressful event normally stops within a minute or two of rest, and open-mouth breathing that continues, or that appears in heat, carries meaning. Blue or grey gums or tongue mean the blood is carrying too little oxygen, and very pale gums can reflect anaemia, bleeding or shock. Laboured breathing differs from the easy panting a dog uses to cool down after exercise, which settles with rest and shade while the dog stays bright and can lie down comfortably.

Cardiorespiratory

Heart and lung disease account for much laboured breathing. In dogs, heart failure from mitral valve disease or dilated cardiomyopathy can fill the lungs with fluid, while brachycephalic airway syndrome and laryngeal paralysis narrow the upper airway. In cats, lung and airway disease such as asthma, heart failure from cardiomyopathy, and fluid around the lungs (pleural effusion) are among the most frequent causes, and a cat with heart disease may show no earlier signs before its breathing becomes laboured. Pneumonia, tumours in the chest, and lungworm (Angiostrongylus vasorum, which dogs in the UK acquire by eating slugs and snails) are further causes.

Metabolic

Disturbances in blood chemistry, such as changes in acid-base balance or electrolyte levels, can drive increased respiratory effort as the body attempts to correct imbalances. Diabetic ketoacidosis and kidney failure may present this way. Anaemia, whether from immune-mediated destruction of red blood cells or from bleeding such as that caused by anticoagulant rat poisons, and paracetamol poisoning in cats both reduce the blood's ability to carry oxygen and can drive faster, harder breathing.

Anatomical

Structural factors in the airways or chest wall can increase the resistance to airflow or limit lung expansion. This may involve breed-related airway anatomy, masses occupying space within the chest, or changes in the shape or mobility of the thoracic cavity.

Thermal regulation

Panting is the normal way dogs lose heat, and after exercise or in warm weather it settles within minutes of rest and cooling. Breathing effort that does not settle, especially with a very red or dark tongue, heavy drooling, wobbliness or collapse, can reflect heatstroke, which can damage organs within a short time. Flat-faced breeds and dogs with laryngeal paralysis are less able to cool themselves and can overheat on warm days or with modest exercise. A cat breathing with its mouth open is not simply cooling down in the way a panting dog is.

Pain or discomfort

Discomfort in the chest wall, abdomen, or elsewhere may alter breathing pattern as animals adjust their effort to minimise pain. This can involve musculoskeletal injury, inflammation of the pleura, or abdominal distension pressing against the diaphragm. In large, deep-chested dogs, restlessness, unproductive retching and a swelling belly alongside laboured breathing form the pattern of gastric dilatation-volvulus (GDV), in which the stomach twists and which can be fatal within hours. It cannot be separated from simple bloat without radiographs.

Behavioural or emotional

Anxiety, fear, or excitement can transiently increase respiratory rate and effort through autonomic nervous system activity. This is usually brief and settles when the trigger passes. Anxiety is a poor explanation for breathing effort that continues at rest, during sleep or in calm surroundings, and an animal in respiratory distress often looks anxious because it cannot get enough air.

Trauma

Blunt trauma, such as a road accident or a fall from height, is a common cause of laboured breathing. Bruising of the lungs, air escaping around the lungs (pneumothorax), bleeding into the chest or a tear in the diaphragm can develop or worsen over the hours after an injury, so an animal can seem steady at first. In a French study of 258 cats admitted to a critical care unit in severe breathing distress, trauma accounted for around one case in five, and those cats were much younger than the rest, with a median age of two years.

Why timing matters

Early observation

When laboured breathing first appears, the context in which it occurs often provides clues to its nature. A pattern that coincides with exertion, warm environments, or specific activities may point towards one set of mechanisms, although effort in these settings that does not settle with rest and cooling can reflect heatstroke or an upper airway crisis in flat-faced breeds or dogs with laryngeal paralysis, which can progress within hours. Breathing effort present at rest or during sleep suggests other mechanisms, including heart failure, fluid or air around the lungs, airway obstruction and lung disease, which can also progress within hours. The accompanying signs at this stage, such as cough, posture changes, or vocalisations, can help build a picture of what systems may be involved.

Later presentation

If laboured breathing persists beyond the situation in which it began, or if it recurs with increasing frequency, this can indicate that an underlying process is not resolving on its own or is evolving. Changes in the character of the breathing, such as the development of audible sounds, shifts in posture preference, or alterations in activity tolerance, may signal progression. What begins as intermittent effort may become more continuous, and patterns observed only during activity may begin to appear at rest.

The trajectory of laboured breathing varies widely depending on its origin. Some patterns, such as those of tracheal collapse or chronic bronchitis, can stay stable for long periods between flare-ups. Others deteriorate over days to weeks, and some, including heart failure, pleural effusion, pneumothorax, upper airway obstruction, heatstroke and gastric dilatation-volvulus, can move from mild effort to collapse within hours. In the same French study of 258 cats, all of them needing oxygen, 44 per cent did not survive to leave hospital. That figure describes cats already in crisis, not milder breathing changes. Individual variation in compensatory capacity, age, and concurrent health influences how quickly changes become apparent. In some cases, breathing effort may fluctuate in response to environmental factors, treatment, or disease activity, so for milder, longstanding effort the overall trend is informative, whereas a single observation of effort at rest, open-mouth breathing in a cat that continues beyond a minute or two of rest or appears in heat, effort after exercise or in warm weather that does not settle within minutes of rest and cooling, or a change in gum colour carries meaning on its own.

Conditions commonly associated

Pericardial Effusion

Reduced cardiac output and potential pleural effusion cause increased respiratory effort.

Feline Asthma

Feline asthma involves chronic inflammation and spasm of the airways, which narrows the passages through which air moves. This narrowing can make breathing visibly effortful, particularly during episodes when inflammation or bronchospasm worsens.

Laryngeal Paralysis in Dogs

In laryngeal paralysis, the cartilages that normally open the larynx during inhalation fail to move aside, leaving a narrowed airway. This obstruction increases the work of breathing, often becoming more pronounced during exertion or in warm conditions, when panting cannot move enough air and affected dogs can overheat.

Tracheal Collapse in Dogs

Tracheal collapse involves flattening of the windpipe when air moves through it, which restricts airflow and can make breathing effortful. The degree of obstruction may vary with activity, excitement, or pressure on the neck.

Pneumonia

Pneumonia involves inflammation and fluid accumulation within the lung tissue itself, impairing the exchange of oxygen and carbon dioxide. This disruption can make breathing both more rapid and more laboured, often accompanied by other signs of systemic illness.

Hypertrophic Cardiomyopathy in Cats

Hypertrophic cardiomyopathy can lead to fluid accumulation in or around the lungs when the thickened, stiff heart muscle cannot fill properly and pressure backs up into the lungs. This fluid burden increases the effort required to breathe and may appear suddenly, sometimes in a cat that showed no earlier sign of heart disease, and can occur alongside sudden hind-limb paralysis if a clot has formed.

Anticoagulant Rodenticide Toxicity

Bleeding into the chest cavity or into the lungs is a recognised complication of anticoagulant poisoning and can make breathing laboured. Signs of bleeding typically appear 3 to 7 days after the poison was eaten, so the link to an earlier exposure is easy to miss.

Aspiration Pneumonia

Affected lung tissue struggles to expand properly, so each breath takes visibly more effort.

Chylothorax

Fluid pooling around the lungs restricts their normal expansion, making each breath more effortful.

Eosinophilic Bronchopneumopathy

As eosinophilic inflammation thickens the airway walls, moving air in and out becomes visibly more effortful.

Paracetamol Toxicity in Cats

The toxin converts haemoglobin into a form that cannot carry oxygen properly, making each breath appear more effortful.

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Pneumothorax

A collapsed lung cannot inflate normally, making each breath visibly effortful.

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Pulmonary Thromboembolism

Blocked pulmonary blood vessels raise pressure within the lungs and impair oxygen exchange, making each breath visibly harder work.

Pyothorax

As infected fluid accumulates around the lungs, each breath requires more effort to overcome the restricted space available for lung expansion.

Tricuspid Valve Dysplasia

Congestion building up behind the affected valve can make each breath visibly more effortful.

Megaoesophagus in Cats

If regurgitated material is inhaled into the lungs, the resulting irritation or infection can make breathing noticeably more effortful.

Pleural Effusion

Fluid filling the space around the lungs limits how far they can expand, so breathing becomes noticeably more effortful.

Congestive Heart Failure in Dogs

Fluid backing up into or around the lungs from a failing heart makes breathing fast and effortful. A rise in the sleeping breathing rate is often one of the first changes owners can count at home.

Mitral Valve Disease in Dogs

Mitral valve disease is among the most common heart diseases of older small-breed dogs. When it progresses to heart failure, fluid collects in the lungs and breathing becomes fast and laboured, often noticed first as a raised breathing rate during sleep.

Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs

Narrow nostrils, an overlong soft palate and a narrow windpipe increase the work of breathing in flat-faced breeds. Noisy, effortful breathing tends to worsen with heat, exercise and excitement, and can progress to collapse on warm days.

Angiostrongylus (Lungworm)

Lungworm, which dogs in the UK acquire by eating slugs and snails, can cause coughing, tiring easily and laboured breathing, sometimes alongside bleeding problems such as nosebleeds or bleeding from minor wounds.

Gastric Dilatation-Volvulus (GDV) in Dogs

A gas-filled, twisted stomach presses on the diaphragm and impairs circulation, so affected dogs often breathe with visible effort alongside restlessness, unproductive retching and a swelling abdomen, and the condition can be fatal within hours.

Immune-Mediated Haemolytic Anaemia (IMHA)

Destruction of red blood cells leaves less capacity to carry oxygen, so breathing can become fast and effortful, often with pale or yellow gums and weakness.

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Aortic Thromboembolism in Cats

Most affected cats have underlying heart disease, and breathing is often fast or laboured from heart failure, alongside sudden, painful paralysis of one or both hind legs.

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When to explore further

If breathing is laboured at rest or during sleep, or if effort after activity or in warm weather does not settle within minutes of rest and cooling. A sleeping breathing rate consistently above about 30 breaths a minute is uncommon even in dogs and cats whose heart failure is well controlled, and a rising sleeping rate in an animal with known heart disease can be an early sign of fluid building up in the lungs.

If laboured breathing comes with blue, grey or very pale gums, open-mouth breathing in a cat, an outstretched neck with the elbows held out, collapse, unproductive retching with a swelling belly in a large dog, or an inability to lie down and settle. These signs show the body struggling to get enough oxygen, and an animal in this state can deteriorate within minutes to hours. Fluid in the lungs, fluid or air around the lungs and a blocked airway cannot be told apart by watching at home. They are distinguished by clinical examination, with imaging such as radiographs or ultrasound for the chest and an examination of the throat under sedation for the upper airway.

If there is progressive reduction in tolerance for normal activity, such as shortened walks, reluctance to climb stairs, or increased time spent resting, this may indicate declining reserve capacity.

If laboured breathing is paired with coughing, weight loss, reduced appetite, or a belly that swells gradually over days or weeks, multiple systems may be involved or a single process may be advancing.

If milder effort that appears only with activity and settles with rest has persisted, or recurs with increasing frequency over weeks. A gradual pattern like this is different from breathing that is laboured at rest, where the picture can change within hours and a wait of days is not a neutral choice.

If breathing becomes laboured in the hours or days after a road accident, fall or fight, or after possible access to rat poison. Bleeding from anticoagulant rodenticides typically shows 3 to 7 days after ingestion and can fill the chest or lungs with blood, and chest injuries can worsen after an animal first seems steady.

Laboured breathing gains meaning when considered alongside the animal's history, other observations, and the contexts in which the pattern appears or resolves. Noting what accompanies the breathing effort, such as posture, sound, activity level, appetite, and changes over time, builds a fuller picture. These observations, when shared with those familiar with the individual animal's health, help clarify whether the pattern reflects a transient response, such as panting after exercise that settles with rest, or a slower process. Breathing that is laboured at rest or in sleep, open-mouth breathing in a cat that continues beyond a minute or two of rest or appears in heat, effort after exercise or in warm weather that does not settle within minutes of rest and cooling, or a change in gum colour sits outside that watch-and-note approach, because its course can change within hours.

Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS