Coughing in dogs

Overview

A protective reflex and a persistent symptom

Irritation triggers a brief, forceful expulsion of air from the lungs. The diaphragm and chest, laryngeal and abdominal muscles work together. Before forceful exhalation, the opening between the vocal folds briefly closes and chest pressure rises. Opening it releases air rapidly. Bordetella bronchiseptica, a kennel cough bacterium, can sensitise the reflex. Coughs can originate at different points between larynx and lungs. Coughing lasting at least eight weeks is chronic.

A UK referral group of 329 persistently coughing dogs most commonly had airway collapse, affecting 30.7%. Chronic bronchitis occurred in 24.3%. Tumours occurred in 18.8%. Infectious bronchopulmonary inflammation affected 16.4%. Laryngeal paralysis occurred in 8.8%. A dog could have several contributing diseases.

Causes

Airway disease and foreign bodies

Sudden cough can accompany viral or bacterial kennel cough. Pneumonia can follow inhalation of vomit or oesophageal contents. Laryngeal dysfunction can predispose to aspiration through inadequate airway closure. Chronic bronchial lining inflammation can sustain coughing. Tracheal collapse involves flattened supporting cartilage rings narrowing the airway. Lung tissue inflammation can cause productive coughing. Fox lungworm can also cause respiratory signs in pet dogs. Lung or airway tumours can cause persistent cough. A bronchial foreign body such as a grass awn can sustain irritation and inflammation.

Heart disease in a coughing dog

Left-sided heart failure can accumulate lung fluid, called pulmonary oedema. Murmurs and coughing can also coexist when airway disease causes the cough. One CT study found several bronchi narrower in coughing dogs with murmurs than controls. An X-ray comparison in mitral regurgitation found narrowing did not distinguish coughing from non-coughing dogs. CT narrowing could also reflect airway disease such as chronic bronchitis. Heart and airway disease can coexist and both contribute.

Risk factors

Collapse particularly affects small dogs such as Yorkshire Terriers, Pomeranians and Chihuahuas. Coughing dogs under 10 kg in the UK referral group had a collapse odds ratio of 2.5 versus heavier dogs. Large-group contact increases kennel cough transmission opportunities. In one endoscopy study, 49 of 63 dogs treated for bronchial grass awns were hunting dogs. Older referral patients more often had tumours than younger ones. Megaoesophagus with regurgitation increases aspiration risk. Excess weight can worsen chronic respiratory coughing. Excitement can trigger episodes in tracheal collapse.

Typical symptoms

Sound and circumstances help investigate the cause. Swallowed mucus can hide a cough's productive nature from owners.

• Tracheal narrowing can cause a dry, goose-honk cough.
• Kennel cough can end a dry bout with gagging.
• Collar tightening can trigger coughing with tracheal collapse.
• Respiratory disease can increase exercise fatigue.
• Nasal discharge can accompany coughing.
• Blood can accompany conditions such as airway tumours.

Reverse sneezing involves rapid, noisy nasal inhalation. The mouth typically remains closed. Episodes can last seconds to minutes. Dust irritating the nasopharynx can trigger them.

In the UK referral population, paroxysmal coughing had a collapse odds ratio of 4.9 versus other coughing dogs. Reduced exercise tolerance was reported in 22.5% of referral patients.

Complications and consequences

Breathing difficulty and persistent cough effects

Persistent dry coughing can damage airway lining. Severe bouts can occasionally cause fainting. Breathlessness-related stress can further worsen coughing. Severe distress can turn mucous membranes grey or blue before breathing stops. Infection can spread into lung tissue as pneumonia. Retained grass awns can sustain purulent bronchitis. Severe bacterial pneumonia can involve sepsis. Complete obstruction can threaten life within minutes.

Diagnosis at the vet

Investigating the cough

Onset helps distinguish acute from persistent coughing. The vet listens for abnormal lung sounds. Heart auscultation can identify murmurs or arrhythmia. High-pitched inhalation can prompt laryngeal investigation. Crackles can occur with oedema, fibrosis or inflammation. Coughing on tracheal palpation alone does not establish tracheal disease. Chest X-rays assess lung structure and heart size. Standard images do not always reveal tracheal collapse. Fluoroscopy, moving X-ray imaging, can show diameter changes during breathing.

Heart, lung and airway investigations

Echocardiography can assess structural heart changes. Suspected cardiac oedema also requires chest imaging. Blood NT-proBNP can supplement uncertain cardiac versus respiratory assessment. Bronchoscopy can seek retained foreign bodies. Lavage assesses inflammatory cells. Culture helps establish antibiotic susceptibility. Fever with coughing raises pneumonia suspicion. Blood cell counts can supplement X-rays for suspected pneumonia. Airway sampling may be unsafe in oxygen-dependent patients. Baermann faecal testing can seek fox lungworm.

One study from northern Europe found median CRP of 121 mg/l in bacterial pneumonia. Chronic bronchitis had 13 mg/l in the same study. The pneumonia group's interquartile range was 68–178 mg/l.

Treatment

Treating the cause

If oxygen supply is inadequate, the vet can provide supplemental oxygen. Bronchoscopy removed grass awns from 63 of 227 dogs examined in one study. Mild kennel cough usually resolves without antimicrobials. Bacterial pneumonia treatment can be targeted using airway culture and susceptibility testing. Severe illness can warrant starting before results return. Aspiration inflammation can be chemical, so antibiotics are not always necessary. Lungworm cough needs an effective antiparasitic.

Corticosteroids can control chronic bronchial inflammation. Diuretics can treat cardiac pulmonary oedema. Medication can ease collapse symptoms, particularly with mild narrowing. Severe tracheal narrowing can prompt consideration of an internal mesh stent.

When is coughing suppressed?

Persistent dry coughing impairing quality of life may warrant a suppressant. Suppression can harm dogs needing to clear secretions. Drowsiness is a possible adverse effect. Heavy lower-airway mucus may prompt saline nebulisation. Underlying disease is treated alongside symptoms where possible.

Prevention

Smoke and other airborne irritants can worsen chronic respiratory coughing. Avoiding strong air fresheners and fragrances can reduce irritation indoors. Harnesses reduce neck pressure compared with collars in tracheal narrowing. A cool resting place helps avoid heat stress with chronic respiratory disease.

Some kennel clubs recommend kennel cough vaccination for event participants. Some clubs require at least two symptom-free weeks before returning to events. Under those rules, restrictions also cover asymptomatic dogs in the same household.

Read about dog vaccinations.

Important for dog owners

Record when coughing began and how often bouts recur. Note mucus or gagging afterwards. Record triggers such as excitement or collar pressure.

Even healthy dogs can breathe faster after exercise. Dogs owners considered asymptomatic and older than 12 months had a median resting rate of 15.7 breaths per minute in one study. Puppies up to 12 months had a median of 20.1.

With heart disease, monitor breathing during peaceful sleep. Count one inhalation and exhalation together as one breath. You can count for 15 seconds. Multiply by four for breaths per minute. Compare with previous readings because individual baselines vary. Call a vet for repeatedly more than 35 breaths per minute during sleep. Laboured breathing needs emergency care without waiting to count.

Frequently asked questions

Does coughing mean heart failure?

Murmurs and coughing can coexist because of respiratory disease. Chest X-rays assess fluid in the lungs. Echocardiography adds structural information when needed. Faster resting breathing warrants reassessment in dogs with heart disease.

How does reverse sneezing differ?

Coughing forcefully expels air from the lungs. Reverse sneezing repeatedly draws air in through the nose. Dogs usually recover quickly after brief, mild episodes. Prolonged or frequent episodes warrant investigation.

Can I give human cough medicine?

The need to suppress coughing depends on its cause. Ask a vet before giving human cough medicine. With substantial secretions, coughing may be needed to clear them. Some human syrups contain xylitol, which is dangerous to dogs.

What if coughing starts during play?

Stop exercise if breathing becomes difficult. Inadequate airflow or a weak cough can indicate obstruction. Call an emergency clinic and seek care immediately for laboured breathing or weakness.

Can vaccinated dogs catch kennel cough?

Vaccines protect against some infectious causes. A Bordetella bronchiseptica vaccine is available, for example. Vaccinated dogs can still become ill. Disease after exposure is generally less marked than in unvaccinated dogs. Dogs with infectious kennel cough should not attend events while symptomatic.