Chest Infection in Cats

Cats younger than three years old, as well as those that live in multi-cat households, have a predisposition for developing chest infections. There are no predispositions based on sex or breed. Pyothorax is more often seen in the summer and fall. Early diagnosis and treatment are vital to ensuring a good prognosis.

Chest infection in cats – known by its technical name, pyothorax – is a serious condition characterized by the formation of pus within the chest cavity. Chest infection may be caused by external trauma such as deep wounds to the trachea or chest and the presence of foreign bodies in the chest cavity. Chest infection may also be caused by a bacterial infection that spreads from the lungs. In most cases of pyothorax, the cause is never identified.

Respiratory problems in cats should always be treated as a veterinary emergency as they may cause sudden death even without clinical signs. Seek immediate veterinary attention if you notice any of the following symptoms:

• Decrease in appetite
• Lethargy and/or weakness
• Weight loss
• Dehydration
• Rapid, difficult breathing
• Coughing
• Excess production of saliva*
• Low or weak heart rate*
• Signs of pain
• Depression
• Fever

*Indicates serious, life-threatening symptoms

There are many factors that can cause chest infection in cats. These include:

• Deep puncture wounds, such as bite wounds
• Damage to the trachea and/or esophagus
• Bacterial pneumonia
• Abscess in the lungs
• The presence of foreign bodies
• Infection spread from the lungs
• Certain cancers
• Parasites in the lungs
• Certain medications

In many cases of chest infection, the cause may never be identified. The primary focus is on immediate identification of infection and treatment. The cause will likely be resolved with treatment.

Your vet will first perform a thorough physical examination, reaching a tentative diagnosis of pyothorax based on presentation of symptoms. Be sure to inform your vet of the extent and duration of your cat’s symptoms, as well as any past pulmonary conditions, recent medications, and medical procedures.

Your vet will reach a definitive diagnosis by performing an x-ray of the chest. A “chest tap” – a procedure in which the vet drains the fluid from the chest – may be required before x-rays are taken. This may require sedation. Once the fluid has been drained, a sample will be sent off to a laboratory for testing. Blood tests may aid in identifying the cause of chest infection. Additional testing may be required based on the suspected cause.

Treatment will depend on the underlying cause and severity of the chest infection. The primary objective of treatment is removing the fluid from the chest cavity. This will require hospitalization, anesthetic, and the placement of a chest tube. Pain medications and intravenous fluid and antibiotic therapy are typically administered as well. Oxygen therapy may also be required.

Your cat may be hospitalized for five to seven days, and will be monitored twenty-four hours a day during hospitalization. The veterinary surgeon will flush your cat’s chest cavity twice daily with a saline solution. Fluid analysis and x-rays will also be performed each day to ensure healing. 

The surgeon will remove the chest tube once the underlying infection has been eradicated and/or the fluid has been successfully drained. Following surgical treatment, your vet will typically prescribe antibiotics for up to six weeks following surgery.

Recovery and prognosis depend on the severity of the condition, when it was diagnosed, and the effectiveness of treatment. For most cases, the prognosis ranges from fair to good. Most deaths associated with pyothorax occur during the first day of hospitalization, as well as in cases in which excess salivation and abnormal or slow heart rate are present.

Always follow your vet’s post-operative instructions carefully. On the return home, ensure your cat has a warm, safe place to rest. Don’t allow your cat to irritate the surgery site. An Elizabethan collar may help with this. If your cat has been placed on antibiotics, it is imperative that you administer the medication for the entire recommended duration of treatment even if the condition starts to improve. Failure to do so could result in aggressive recurrence.

Your vet will schedule a follow-up appointment one week after surgery, and will perform chest x-rays and blood tests during this time. Additional follow-up appointments will be scheduled one week after antibiotic therapy has concluded, and again in one month.