When to see a vet urgently
Go to an emergency vet immediately and tell them you are coming if your cat has:
- open-mouth breathing or clearly laboured breathing at rest;
- a bluish tongue, collapse or severe weakness;
- a penetrating chest wound or breathing difficulty after an accident;
- rapidly worsening breathing after a chest procedure.
Do not wait for every symptom to appear. You can find a vet near you.
Overview
Normally, the pleural space contains only a thin layer of fluid that allows the lungs to glide smoothly. In pneumothorax, air enters through damage to the chest wall, a tear in lung tissue or spontaneous rupture of air-filled blisters called bullae. The lung then partially or completely collapses, gas exchange is impaired and oxygen levels fall.
This is air outside the lung, rather than an increase in air inside its air sacs. The pressure difference between the lung and chest normally helps the lung follow breathing movements. When this relationship is disrupted, inhalation does not expand the lung normally even though the chest moves.
The volume of free air, its rate of accumulation and the lungs' underlying condition affect symptoms. A small pneumothorax may occasionally be discovered during another investigation without severe breathlessness. A vet must still decide its significance and monitoring needs. An outwardly calm appearance alone does not show that there is little air or that the condition will remain stable.
Causes
- Traumatic pneumothorax follows chest wounds, including bites, penetrating injuries and road accidents.
- Spontaneous pneumothorax results from rupture of bullae, cysts or lung tissue and occurs in cats with chronic lung disease.
- Iatrogenic pneumothorax is a complication of medical procedures, such as thoracocentesis, surgery or mechanical ventilation.
A blunt impact to the chest can damage a lung without a visible hole in the skin. Spontaneous pneumothorax means there is no identified injury or causative medical procedure. It does not mean the lung is otherwise healthy. In cats, underlying conditions described include inflammatory airway disease, tumours, lung abscesses and parasitic infections.
Ruptured bullae, or air-filled blisters, are a recognised cause in dogs, but the distribution of canine disease should not be transferred directly to cats. Travel and previous residence may also affect which underlying diseases are investigated. Testing guided by findings is more useful than assuming every possible cause is equally likely.
Risk factors
- Cats with outdoor access, through injuries, road accidents and fights.
- Cats with chronic lung disease, such as asthma or bullous emphysema.
- Cats recovering from surgery or intensive respiratory support.
- Young, active cats at greater risk of injury.
Information on risk factors for spontaneous pneumothorax in cats is limited, and no clearly predisposed breed or age group is known. Youth and activity relate mainly to the opportunity for an accident. Conversely, an indoor cat can develop pneumothorax associated with another lung disease. No history of surgery does not rule it out.
Typical symptoms
- Sudden breathlessness and rapid breathing.
- Shallow breathing with obvious abdominal muscle effort.
- Restlessness, panic or, conversely, sudden weakness.
- Sitting with the neck extended and elbows held out.
- Pale mucous membranes or cyanosis.
- A rapid heart rate and weak pulse.
- In open pneumothorax, a chest wound with an audible sucking sound.
Bluish colour is a serious sign you should not wait to see. A cat may hide, stop eating or resist movement because of breathing difficulty. However, asthma, fluid around the lungs and heart-related breathing problems cause similar signs. Pneumothorax cannot be confirmed at home from posture or by feeling the chest.
In open pneumothorax, a wound may connect the pleural space to outside air, but a visible wound or audible sucking sound is not essential. In closed pneumothorax, air can leak from the lung into the chest while the skin remains intact. Tell your vet about a suspected fall or brief escape too, even if no actual collision was seen.
Complications and consequences
- Respiratory failure.
- Shock.
- Reaccumulation of air.
- Death if help is not received in time.
In particularly dangerous tension pneumothorax, accumulating chest air can impair blood returning to the heart as well as breathing. Circulation may then collapse rapidly. Supplemental oxygen alone does not relieve pressure around the lung: the air must be removed. Underlying lung damage or other traumatic injuries can affect oxygenation even after air removal.
Diagnosis at the vet
- Clinical examination, including reduced or absent breathing sounds and signs of lung collapse.
- Chest X-rays showing collapsed lungs and air in the pleural space.
- Chest ultrasound showing absent pleural sliding.
- Thoracocentesis to confirm air.
- Blood tests to assess oxygen deficiency and acidity.
A cat with severe breathing difficulty is stabilised first. Imaging must not unnecessarily delay life-saving care, and the vet may need to remove air before comprehensive X-rays. Oxygen and minimal handling help arrange investigations safely. A breathless cat is not forced to remain in an examination position just to obtain a perfect image.
X-rays may show free air and the lung pulling away from the chest wall. They confirm pneumothorax but do not always reveal the source of the leak. CT may be considered later to investigate a localised lung lesion or the need for surgery, for example. Imaging is timed according to the cat's condition.
Ultrasound can often be performed in a position the cat tolerates. Absent pleural sliding suggests pneumothorax but is assessed alongside other imaging and examination findings. Blood gas analysis can show oxygenation and acid–base balance. It does not alone establish the cause of breathing difficulty. Accident patients are also checked for other injuries.
Treatment
- Emergency thoracocentesis to remove air from the pleural space through a catheter or needle.
- Placement of a chest drain if air reaccumulates.
- Oxygen therapy.
- Treatment of the underlying cause, such as wound closure, surgical removal of bullae or cysts, or infection treatment.
- Fluids and supportive treatment for shock.
Thoracocentesis is also therapeutic: removing air gives the lung room to expand. However, it does not itself repair a leaking area of lung or the underlying disease. If air accumulates continuously or repeated procedures would be needed, a chest drain allows controlled air removal and monitoring of the ongoing leak.
A chest drain is a tube placed into the chest cavity and managed under hospital supervision. Do not try to remove air yourself with a needle or open drain connections. Pain relief and other support are planned alongside this. Fluids for shock are chosen according to the patient's circulation and lung condition.
Not every cat needs surgery. In some cases, a small, stable pneumothorax can settle under supervision with treatment of the underlying disease. Persistent leakage, severe recurrence or a localised removable lesion may favour surgery, such as removal of a diseased lung lobe. The decision is based on the individual cat's findings. Surgical results reported for dogs are not an individual cat's prognosis.
Safe transport
Keep your cat as calm as possible and allow a position that makes breathing easier. Do not squeeze its chest against you or wrap a tight bandage around it. Keep the carrier ventilated. Avoid forcing the mouth open or other unnecessary examination before leaving. Call the practice while preparing transport.
If an object is embedded in the chest, do not pull it out. Ask how to protect the wound and move the animal. After an accident, support the whole body and avoid sudden head, neck or back movements. Protect yourself too, as pain and lack of oxygen can make handling difficult.
Recovery and prognosis
After treatment, breathing and whether the lung stays expanded without new air accumulation are monitored. Temporary relief alone does not show that the leak has stopped. Discharge requires a vet's assessment of stability and a plan for ongoing treatment of any underlying disease. Activity restrictions and wound care after a procedure are specified separately.
At home, watch ease of breathing at rest, movement and eating. New open-mouth breathing, obvious abdominal effort or collapse require another emergency assessment. Do not change existing asthma or other medication on the assumption that new difficulty must have the same cause. Ensure adequate nutrition, but do not force-feed a breathless or resisting cat.
Prognosis depends particularly on the underlying disease, extent of other injuries and whether the leak can be controlled. Less research is available in cats than dogs. Results from small retrospective case series cannot be used as survival percentages for all cats. Your vet refines the assessment according to treatment response and further investigations.
Prevention
- Reduce injury risk by limiting free roaming and taking care during transport.
- Treat chronic lung diseases promptly.
- Monitor your cat closely after chest surgery and procedures involving the lungs.
Not every spontaneous case can be prevented. Monitoring lung disease and following agreed treatment help identify changes, but previously good control does not make sudden breathlessness harmless. Tell the practice immediately if breathing changes after a procedure or hospitalisation; do not wait for the next scheduled check.
Important for cat owners
Pneumothorax is a sudden, life-threatening condition. Remember that sudden severe breathlessness, bluish mucous membranes and restlessness are reasons to go to a vet or emergency service immediately. Prompt air removal and treatment of the cause substantially improve the chance of survival.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Can pneumothorax occur without an external wound?
Yes. Air leaking from a lung can accumulate in the pleural space while the skin is intact. Blunt trauma or underlying lung disease is also possible. No visible wound does not rule it out.
Does removing the air cure pneumothorax?
It helps the lung expand, but the leak or underlying disease may continue. Monitoring is therefore needed, sometimes with a chest drain or surgery. The vet decides the next steps from the cat's condition and investigations.
Does a cat always need surgery?
Not always. Supervised conservative treatment suits some cats, while persistent leakage or a removable lung lesion may require surgery. You cannot safely determine the suitable option at home from symptom severity.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Disorders of the Chest Cavity of Cats, Merck Veterinary Manual, accessed 2026-11-05.
- Spontaneous Pneumothorax, American College of Veterinary Surgeons, accessed 2026-11-05.
- Spontaneous pneumothorax in 35 cats (2001–2010), Journal of Feline Medicine and Surgery, accessed 2026-11-05.
- Initial Triage and Resuscitation of Small Animal Emergency Patients, Merck Veterinary Manual, accessed 2026-11-05.
- Dyspnea (Difficulty Breathing), Cornell Feline Health Centre, accessed 2026-11-05.
- First Aid and Transport of Small Animals, Merck Veterinary Manual, accessed 2026-11-05.
- 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat, Journal of Feline Medicine and Surgery, accessed 2026-11-05.