Pus in the Chest Cavity in Cats

A pyothorax is an accumulation of fluids that can be red, brown, or yellow in color when aspirated for diagnostic cytological analysis. The cause of pyothorax in felines is subject to debate, as veterinary specialist have linked several possible causes to this infectious condition. Research has shown, however, that pyothorax is not a hereditary predisposition of any one feline breed and that felines under the age of three are at greater risk of developing the condition than older cats.

Pus in the chest cavity in cats is known as a pyothorax. In the medical term, pyothorax, “pyo” means “pus” and “thorax” is the area of a cat’s chest, thus a pyothorax is a septic effusion found in the pleural space.

Pus in the chest cavity in cats will cause a great deal of respiratory distress to your feline. The feline may have a difficult time breathing during regular activities and laying on her side often increases the distress in moving air to the lungs.  Pet owners may notice their cat avoids physically challenging situations, such as going up stairs or engaging in playful encounters. The feline may keep her mouth open to push more air into her lungs, a clear indication of severe respiratory distress. Symptoms that have been reported in cats with pus in the chest cavity includes:  

• Respiratory distress
• Shallow breathing
• Open mouth breathing
• Depression
• Painful breathing 
• Weight loss
• Tachypnea (rapid breathing)
• Weakness
• Lethargy
• Anorexia (decreased appetite)
• Poor body condition
• Dull hair coat
• Dehydration 
• Pyrexia (fever)

The exact cause of pus in the chest cavity in cats is a subject of debate among veterinary specialist. An infection of bacterial origin in the agreed cause of pyothorax in felines, but how the infection reached the thoracic cavity could be caused by: 

• A bite to the feline’s chest
• Dental disease that has caused bacteria to enter the bloodstream. 
• Foreign bodies that have migrated into the chest upon respiration 
• Damage to the trachea or esophagus 
• Bacterial pneumonia 
• Lung parasites
• Pulmonary abscess

The veterinarian will begin his or her diagnosis of pyothorax with a review of the feline’s medical history and confirming recent symptoms with the cat owner. The veterinarian will likely listen to the feline’s breathing with a stethoscope. If there is, in fact, fluid in the chest cavity, an auscultation of the thorax will likely reveal a decreased exhalation of air coming from the lungs and a muffled heartbeat. Radiographs often follow the physical examination, revealing the presence of bilateral or unilateral fluid within the feline’s chest. Ultrasounds are soon to follow an x-ray to determine if there is a presence of lung masses or abscesses that are accompanying the fluids.

A test called a thoracentesis, or chest tap, is the removal of fluids within the thoracic cavity for cytological analysis. The feline is sedated for this diagnostic procedure and the samples collected from the chest cavity are later evaluated by a laboratory expert. The fluid samples collected during the chest tap are necessary for determining the nature of the infection and aid the veterinarian in deciding a treatment plan. 

The key focus in a feline pyothorax case is to remove the fluids from the chest cavity and deliver an aggressive therapeutic regimen of antibacterial agents to the feline. A drain, usually a flexible catheter, is inserted into the affected chest area, allowing fluids to be removed from the body. Removing the fluids from the chest will alleviate pressure from the lungs, allowing the feline to regain normal breathing habits. The affected area may be flushed out to remove the pus and infection directly from the source, however, antibiotics are required. Antibiotics are often given to the feline orally, but can also be delivered through a surgically placed drain. Your cat will likely be hospitalized for roughly a week, as it takes several days for the fluids to completely drain from the chest.

Based on previous cases of feline pyothorax, the prognosis for pus in the chest cavity in cats is good to fair. If the symptoms initiated an early intervention and the infection was treated appropriately by a licensed veterinary professional, your cat’s prognosis is very positive. It is rare for a pyothorax to recur, with only a small percentage of the affected population reported to have the problem return. To receive such a high prognosis, pet owners must dedicate at least six weeks of treatment and keep all check-up visits as directed by their veterinarian.