How to Recognize Fluid in a Cat’s Lungs

Various medical problems can lead to shortness of breath in cats. Many cat owners associate breathing problems with fluid in the lungs, and ask for assistance in recognizing symptoms of this particular issue.

The medical term for the accumulation of fluid in the lungs is pulmonary edema. This condition can be caused by congestive heart failure, trauma, or an infection like pneumonia. In this article, we will review ways to spot breathing issues in cats and list possible causes for fluid in the lungs.

Spotting Dyspnea

Difficulty breathing (or shortness of breath) is commonly referred to by the medical term dyspnea. This can manifest in cats as an increased respiratory rate, increased respiratory effort (working harder to take breaths), open mouth breathing, and/or an abnormal posture to breathe. Cats that have fluid in their lungs or have difficulty breathing may sit with their head and neck extended and elbows back (see figure 1).

Figure 1. Cat with slight trouble breathing from fluid in lungs. This cat’s elbows are back and neck slightly extended. Some cats may have their neck extended even more as the difficulty progresses.

Difficulty breathing can occur at any point in a cat’s breathing process, either during inspiration (breathing in) or expiration (breathing out).

Figure 2. This cat is having severe trouble breathing due to fluid in the lungs related to congestive heart failure from hypertrophic cardiomyopathy. His neck is extended, he is very weak, and he is open mouth breathing.

There are many different reasons for shortness of breath. When a cat has trouble breathing, they may not be able to get an adequate supply of oxygen to their tissues. For example, there can be airway problems from asthma, a foreign body in the airway causing an obstruction, an infection, accumulation of fluid (edema) in the lungs, bruising of the lungs (pulmonary contusions), or an abnormal accumulation of fluid in the chest cavity (pleural effusion).

Why Cat’s Lungs Fill with Fluid

Fluid in a cat’s lungs can be caused by several different diseases. These problems are either categorized as cardiogenic (caused by underlying heart issues) or non-cardiogenic (not caused by underlying heart issues).

Cardiogenic Causes

• Congestive heart failure (CHF) is a condition resulting from the heart’s inability to sufficiently pump blood throughout the body. This failure leads to an increased respiratory effort caused by fluid in or around a cat’s lungs. Two common heart diseases that cause congestive heart failure are hypertrophic cardiomyopathy and dilated cardiomyopathy. These diseases can cause lethargy, weakness, lack of appetite, and decreased exercise capacity. Also, most cats are unable to eat when struggling with breathing difficulties.

Non-Cardiogenic Causes

• Pneumonia is an infection of the lungs that usually results from a bacterial infection. The most common way a cat acquires pneumonia is by inhalation. Cats with pneumonia may suffer from a compromised immune system. This type of infection can occur at any age, but is more common in kittens or senior pets.
• Cancer is an uncontrolled growth of cells on or within the body. Cancer is common in cats and the risk increases with age. In fact, cancer accounts for almost half of the deaths of pets over 10 years of age. It may be localized or invade adjacent tissue and spread throughout the body. Cancer can develop in the lungs, spread to the lungs, or occur in tissues that lead to fluid in or around the lungs. Intact (non-spayed) female cats are predisposed to breast cancer (metastatic mammary carcinoma).
• Upper respiratory tract infections (URTI) are among the most common conditions that occur in cats and kittens. Signs can range from sneezing, running eyes, inflamed conjunctiva, ulcers in the mouth, and/or trouble breathing.
• Head trauma can occur when cats are hit by a car, crushed in a recliner, bitten by another animal, or subjected to other types of trauma. Some cats with head trauma can develop lung inflammation that causes fluid in the lungs.
• Electrocution or electric shock results in injury to nerve cells from the intense heat generated as the electricity passes through the body tissues. The most common source of electrical injury to cats is when they bite electrical cords carrying low voltage household currents. This is most common in young, playful cats and kittens. Exposure to high voltage electrical current is uncommon and can be fatal due to massive internal damage.
• Seizures, also known as fits or convulsions, are a sudden excessive firing of nerves in the brain. They result in a series of involuntary contractions of the voluntary muscles, abnormal sensations, abnormal behaviors, or some combination of these events. A seizure can last from seconds to minutes in cats. They are symptoms of a neurological disorder, but are not a disease. Some underlying causes of seizures in cats include inflammatory brain diseases, brain tumors, symptoms from toxins, or epilepsy.
• Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are severe respiratory diseases that can occur in cats. These diseases are well characterized in human medicine, but not as well researched in cats. Complex changes occur that provoke cellular inflammation, leading to progressive breathing issues and fluid accumulation in the lungs. This most often occurs in cats with an infection or pneumonia.
• Pulmonary contusions, also known as bruising to the lungs, can develop secondary to trauma, such as being hit by a car or falling. Lung damage can cause fluid accumulation within the lungs, leading to difficulty breathing.

Asthma or Fluid in the Lungs?

There are many diseases that can be confused with pulmonary edema, one of which is feline asthma.

Asthma in cats, also known as “feline allergic asthma” or “feline allergic bronchitis,” is a lung condition associated with airway obstruction, typically caused by sudden narrowing of the bronchial tubes. These symptoms are caused by the spasmodic constriction of the bronchial tubes and increased production of secretions from the bronchial tree. Common symptoms in cats include coughing, difficulty breathing, increased respiratory effort, or wheezing. Some cat owners may confuse wheezing with fluid in the lungs.

How to Recognize the Problem

You can recognize fluid in your cat’s lungs by evaluating their breathing. Breathing issues are considered an emergency and cats struggling to breathe should be taking to their veterinarian immediately.

Signs of Fluid in a Cat’s Lungs

• Increased respiratory rate (>40 breaths per minute)
• Increased respiratory effort (working harder to take breaths)
• Open mouth breathing
• Abnormal posture (cats that have difficulty breathing may sit with head and neck extended and elbows back)
• Lethargy
• Weakness
• Reluctance to play
• Hiding
• Withdrawing from family activities
• Coughing

If you see any of the above signs in your cat, visit your veterinarian immediately.

Tests to Determine if Fluid Is in Your Cat’s Lungs

Tests to diagnose abnormal fluid accumulation in the lungs include:

• Physical examination. Your vet may be able to determine if there is a fluid accumulation based on your cat’s clinical signs and auscultation of the lungs.
• X-Rays. Radiographs of the chest (chest x-rays) can help evaluate the size and shape of the heart and diagnosis fluid accumulation.
• Echocardiogram. An ultrasound of the heart, also known as an echocardiogram or “echo,” can aid in the diagnosis of heart failure.
• Other tests. Your vet may also recommend blood pressure measurement and/or laboratory (blood) tests.

Treatment of Fluid in Cat Lungs

Treatment of fluid in cat’s lungs will depend on the underlying cause of the fluid and location of the fluid.

Common treatments include:

• Oxygen supplementation can be administered by placing the cat in an oxygen cage, placing a mask over the mouth and nose (oxygen mask), or by placing an oxygen source in front of the nose (flow-by oxygen).
• Minimization of stress, which may include placing the cat in a cool, quiet location and administering sedation or pain medications to decrease anxiety.
• Thoracentesis is a procedure to drain fluid that has accumulated around the lungs (pleural effusion). This procedure is performed by inserting a small needle between the ribs into the area around the lungs (pleural space) and withdrawing fluid.
• Diuretic medications, commonly referred to as a “water-pill,” can be given orally or by injection. The most common diuretic used is furosemide (Lasix®).
• Heart medications may be recommended depending on the underlying cause.