SYMPTOM
Noisy breathing
Audible breathing sounds at rest or during mild activity, including a low-pitched snoring sound (stertor), a high-pitched harsh sound (stridor), or rasping noises.
Upper Airway Obstruction
Noisy breathing frequently originates from turbulent airflow through a partially obstructed upper airway. Conditions affecting the nasal passages, nasopharynx, larynx, or extrathoracic trachea can all produce audible breathing sounds as air is forced through narrowed passages. The character of the sound, whether it is a snore, stertor, stridor, wheeze, or honk, can help localise the level of obstruction. Inspiratory noise typically suggests obstruction above the thoracic inlet, while expiratory noise may suggest lower airway involvement.
Brachycephalic Obstructive Airway Syndrome (BOAS)
Breeds with shortened skulls face multiple anatomical challenges to normal airflow including stenotic nares, elongated soft palate, hypoplastic trachea, and everted laryngeal saccules. These conformational features produce varying degrees of chronic noisy breathing that may be present from a young age and can worsen with heat, excitement, exercise, or weight gain. Over time, the chronic increased respiratory effort may produce secondary changes including laryngeal collapse that further compromise airway function. The progressive nature of these secondary changes means that breathing noise may gradually worsen even without a new disease process. Flat-faced dogs are over-represented among dogs with heat-related illness and are at greater risk of dying from it, because a narrowed airway limits panting as a way of losing heat.
Laryngeal Disease
Laryngeal paralysis, laryngeal collapse, and laryngeal masses can all produce noisy breathing by impairing the normal opening of the larynx during inspiration. Laryngeal paralysis is particularly common in older large-breed dogs and produces a characteristic inspiratory stridor that worsens with exercise, excitement, or heat. The condition may progress from mild inspiratory noise to severe respiratory distress, particularly during episodes of increased respiratory demand. Changes in the animal's bark or voice may accompany the respiratory noise. In many older dogs, laryngeal paralysis is one part of a slowly progressive nerve disorder known as geriatric onset laryngeal paralysis polyneuropathy, which can also bring hind-limb weakness and a higher risk of megaoesophagus and aspiration pneumonia. Heat and exertion carry particular weight: rapid panting can make the lining of the larynx swell, which narrows the airway further, and a dog that cannot breathe efficiently also cannot cool itself, so an episode can escalate to blue-tinged gums, collapse and heatstroke.
Tracheal Disease
Tracheal collapse, most commonly seen in small-breed dogs, produces a distinctive honking cough and noisy breathing that may worsen with excitement, tracheal pressure from collars, or environmental irritants. The collapsing tracheal rings create intermittent airway narrowing that produces audible turbulence during breathing. Tracheal masses, foreign bodies, or external compression can similarly restrict airflow through the trachea, producing breathing sounds that may be constant or variable depending on the nature of the obstruction.
Lower Airway or Pulmonary
Conditions affecting the bronchi or lung parenchyma can produce noisy breathing through bronchospasm, mucus accumulation, or consolidation that disrupts normal airflow patterns. Feline asthma produces wheezing through bronchial smooth muscle contraction. Chronic bronchitis produces increased mucus that creates crackles and wheezes. Pneumonia or pulmonary oedema may produce crackling sounds as air moves through fluid-filled airways. These lower airway sounds tend to be heard during both inspiration and expiration and may be more apparent during auscultation than audible to the owner at a distance. For this reason, loudness is a poor guide to severity. Fluid in the lungs from heart failure or pneumonia, or fluid around the lungs (pleural effusion), often produces fast, laboured breathing with little audible noise, so quiet breathing is not in itself reassurance.
Sudden-Onset Obstruction
Noisy breathing that appears abruptly in an animal that was breathing quietly hours earlier follows a different course from the gradual causes above. An object lodged in the throat or nasal passages, swelling of the throat from an allergic reaction, injury to the neck, or a sudden crisis in an animal with laryngeal paralysis or brachycephalic airway disease can narrow the airway within minutes. Because the lining of the airway tends to swell further with the effort of breathing, obstruction of this kind can worsen rather than settle, and how narrow the airway has become cannot be judged by listening at home.
Snoring and Reverse Sneezing
Not every noisy breath reflects disease. Many dogs and cats snore in deep sleep, particularly in certain positions, and the noise stops when they wake and breathe normally; in flat-faced breeds, however, loud snoring usually reflects airway narrowing rather than a normal finding. Reverse sneezing is a common episodic event in dogs, and occasionally cats, in which the animal stands still, extends its head and neck, and makes rapid, loud snorting breaths inwards. Episodes usually last from a few seconds to about a minute, often follow waking, exercise, eating or dust, and the animal is entirely normal between them. What separates this from airway obstruction is the return to normal: an episode that does not settle, breathing effort that keeps increasing, or a change in gum or tongue colour does not fit reverse sneezing.
Why timing matters
Early observation
When noisy breathing first becomes apparent, it may be situation-specific: occurring only during sleep, after exercise, in warm weather, or during excitement. At this stage, the noise may be intermittent and the animal may not show any distress or limitation in its normal activities. Early noisy breathing in brachycephalic breeds may be so normalised within the breed that it is not recognised as abnormal. Noting the specific circumstances that provoke the noise, its character, and whether it is present during both inspiration and expiration can provide initial characterisation of the level and nature of the airway involvement.
Later presentation
As the underlying condition progresses, noisy breathing may become more constant, louder, and present during lower levels of activity. The animal may begin to show signs of increased respiratory effort: extended neck, abducted elbows, open-mouth breathing, or visible abdominal push during expiration. Exercise tolerance typically declines, and the animal may seek cool surfaces, avoid warm environments, or become reluctant to engage in physical activity. Episodes of acute respiratory distress may occur, particularly during hot weather, excitement, or exertion, representing moments when the airway's capacity is overwhelmed by respiratory demand. These episodes can progress to heatstroke and collapse, and can be fatal.
The trajectory of noisy breathing depends on the underlying cause. Brachycephalic airway syndrome tends to worsen gradually as secondary changes develop, with weight gain and ageing contributing to declining airway function. Laryngeal paralysis typically progresses slowly over months, often as part of a wider nerve disorder, yet a dog whose larynx is worsening gradually can still have a sudden breathing crisis on a warm day or after exertion. Tracheal collapse may show a more fluctuating course, with periods of relative stability interspersed with worsening triggered by environmental or infectious factors. Understanding whether the breathing noise is stable, gradually worsening, or episodically severe helps characterise the trajectory. Noise that appears suddenly does not follow any of these slower patterns.
Conditions commonly associated
Laryngeal Paralysis in Dogs
Laryngeal paralysis prevents the cartilage flaps of the voice box from opening fully during breathing, narrowing the airway and creating turbulent airflow that produces stridor, a harsh rasping noise, particularly when breathing in. Rapid panting in heat or excitement can make the larynx swell and turn this into a breathing crisis.
Tracheal Collapse in Dogs
Noisy breathing in tracheal collapse results from turbulent airflow through the narrowed tracheal lumen, producing stridorous sounds that may vary with the phase of breathing and the degree of respiratory effort.
Chronic Upper Respiratory Disease in Cats
Chronic upper respiratory disease can produce noisy breathing through nasal congestion, turbinate destruction, and accumulation of mucus within the nasal passages, resulting in stertor and snuffling sounds particularly during rest.
Chronic Bronchitis in Dogs
Noisy breathing in chronic bronchitis reflects turbulent airflow through airways narrowed by inflammation, mucus accumulation, and bronchial wall remodelling, producing wheezes and crackles that are usually heard with a stethoscope, while the sign most owners notice is a persistent cough.
Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs
Brachycephalic obstructive airway syndrome commonly presents with snoring, snorting, and stertor due to anatomical narrowing of the upper airways.
Nasopharyngeal Polyps
Nasopharyngeal polyps commonly cause noisy breathing as they obstruct the airway behind the nasal passages.
Feline Asthma
Feline asthma narrows the lower airways through inflammation and contraction of the airway muscles, producing wheezing and coughing. During an episode a cat may crouch with its neck extended. Open-mouth breathing during an episode marks a severe attack, which can be life-threatening.
When to explore further
Breathing noise that is progressively worsening over weeks to months, with the sounds becoming louder or occurring during lower levels of activity, may suggest a structural airway change that is advancing rather than a stable condition.
When noisy breathing is accompanied by a change in the animal's bark or voice, which may become hoarse, quieter, or altered in pitch, the combination may suggest laryngeal involvement, as the larynx serves both respiratory and vocal functions.
Noisy breathing that escalates to visible struggle carries a different weight from a longstanding, stable noise, even when the underlying condition is chronic. The signs of that shift are concrete: the neck stretched out and elbows held away from the chest, an animal that cannot settle or lie down, gums or tongue turning blue, grey or very pale, collapse, or a noise that becomes quieter while the effort of breathing keeps increasing, which can mean less air is moving rather than more. Airway obstruction of this kind can progress to collapse within minutes to hours, particularly in heat or excitement, and it cannot be relieved or measured at home.
Noisy breathing that is notably worse in warm or humid conditions, and improves in cool environments, may suggest that the airway's reserve capacity is being exceeded during thermoregulation. This pattern can turn quickly: panting makes the lining of the larynx and throat swell, the swelling narrows the airway further, and an animal that cannot pant effectively also cannot cool itself, so warm weather, exercise or excitement can take a dog with laryngeal paralysis or brachycephalic airway disease from noisy breathing to overheating and collapse in a short time.
When noisy breathing develops alongside exercise intolerance, regurgitation after eating, or recurrent respiratory infections, the combination of signs may suggest a more complex airway or swallowing dysfunction rather than a simple single-level obstruction.
Noisy breathing that begins suddenly, rather than developing over weeks, points away from the gradual conditions and towards a lodged object, throat swelling or an acute crisis, where the airway can narrow over minutes. In cats, open-mouth breathing is a marker of significant breathing difficulty. Cats rarely breathe through the mouth. Brief panting after hard play or a stressful journey that settles within a few minutes of rest is the usual exception. Open-mouth breathing at rest, or breathing that does not settle, is not explained by stress.
For a longstanding noise in an animal that is otherwise comfortable, characterising the sound benefits from careful observation of when and how it occurs. Noting whether the noise is primarily during breathing in or breathing out, whether it changes with the animal's position or activity level, and whether specific triggers such as heat, excitement, or eating consistently provoke the sound can help localise and characterise the airway involvement. Recording the sounds, either audio or video, can capture details that may not be reproducible in a clinical setting, as the animal's stress or excitement during examination may alter the breathing pattern from what the owner observes at home. This kind of observation suits a stable pattern. It does not fit a sudden new noise, breathing that is becoming more laboured, or a change in gum colour, where the level and severity of obstruction cannot be judged by ear and the picture can change within minutes.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS