Why Is My Pet Having Trouble Breathing? Common Causes Explained

Now that you understand what normal breathing looks like, let's discuss the many conditions that can make breathing difficult.

One of the biggest misconceptions among pet owners is that all breathing problems come from the lungs.

In reality, breathing involves multiple organs working together. A problem anywhere along the pathway—from the nose to the heart—can interfere with your pet's ability to get enough oxygen.

As veterinarians, we often divide breathing problems into five major categories:

• Upper airway disease
• Lower airway disease
• Lung disease
• Pleural space disease
• Heart disease

Other conditions such as trauma, anemia, heat stroke, allergic reactions, and pain can also affect breathing.

Upper Airway Disease

The upper airway includes the nose, throat, larynx (voice box), and the beginning of the windpipe.

Think of it like the entrance to a tunnel. If that entrance becomes narrow or blocked, getting air into the lungs becomes much more difficult.

Common Causes

Laryngeal paralysis

Brachycephalic Obstructive Airway Syndrome (BOAS)

Foreign objects

Tumors

Severe allergic swelling

Trauma

What You'll Often Notice

Loud breathing

Snoring while awake

High-pitched breathing (stridor)

Difficulty inhaling

Heat intolerance

Exercise intolerance

Laryngeal Paralysis

The larynx contains cartilage that opens every time your pet breathes.

In laryngeal paralysis, those structures no longer open normally.

Instead of widening during inhalation, they remain partially closed, forcing your dog to work much harder to pull air into the lungs.

This condition is most commonly seen in older Labrador Retrievers, Golden Retrievers, and other large-breed dogs.

Symptoms often worsen during:

• Hot weather
• Exercise
• Stress
• Excitement

Severe cases are true emergencies.

Brachycephalic Obstructive Airway Syndrome (BOAS)

Flat-faced breeds are born with anatomy that makes breathing more difficult.

Common breeds include:

• Bulldogs
• French Bulldogs
• Pugs
• Boston Terriers
• Shih Tzus
• Persian cats

These pets may have:

• Narrow nostrils
• An elongated soft palate
• Narrow windpipe
• Tissue that partially blocks airflow

Many owners assume noisy breathing is "normal" for these breeds.

It isn't.

Although common, chronic airway obstruction places significant strain on the respiratory system and increases the risk of overheating and respiratory emergencies.

Lower Airway Disease

The lower airways include the trachea, bronchi, and bronchioles.

These airways carry air deep into the lungs.

When they become inflamed or collapse, airflow becomes restricted.

Common Causes

Tracheal collapse

Chronic bronchitis

Feline asthma

Airway inflammation

Tracheal Collapse

Most commonly seen in small-breed dogs such as:

• Yorkshire Terriers
• Pomeranians
• Toy Poodles
• Chihuahuas

The cartilage supporting the windpipe gradually weakens.

Instead of remaining open, the trachea flattens during breathing.

Owners often describe the cough as sounding like a goose honk.

Symptoms worsen with:

• Obesity
• Heat
• Excitement
• Pulling on a collar
• Feline Asthma

Asthma causes inflammation and narrowing of the small airways within the lungs.

Affected cats may:

• Cough
• Wheeze
• Breathe rapidly
• Have episodes of open-mouth breathing

Some cats recover quickly after an episode.

Others require emergency oxygen therapy and long-term medication.

Lung Disease

Even if air reaches the lungs, oxygen cannot enter the bloodstream if the lung tissue itself is damaged.

Common Causes

Pneumonia

Pulmonary edema

Lung tumors

Pulmonary fibrosis

Fungal infections

Lungworms (in some regions)

Pneumonia

Pneumonia develops when infection or inflammation fills the tiny air sacs of the lungs with fluid and inflammatory cells.

Instead of exchanging oxygen efficiently, portions of the lung become essentially unavailable for breathing.

Symptoms include:

• Fever
• Coughing
• Lethargy
• Rapid breathing
• Loss of appetite
• Pulmonary Edema

Pulmonary edema means fluid has accumulated within the lungs.

This most commonly occurs because of left-sided heart failure but may also result from other serious illnesses.

As fluid fills the lungs, oxygen has farther to travel before reaching the bloodstream.

This causes pets to breathe faster and harder in an attempt to obtain enough oxygen.

Pleural Space Disease

This is one of the most overlooked causes of breathing difficulty.

The lungs sit inside the chest but are surrounded by a thin space called the pleural space.

Normally, this space contains only a tiny amount of lubricating fluid.

When air or fluid accumulates here, the lungs cannot expand normally—even if they are perfectly healthy.

Common Causes

Pleural effusion

Pneumothorax

Chylothorax

Pyothorax

Hemothorax

Pleural Effusion

Pleural effusion means abnormal fluid has collected around the lungs.

Possible causes include:

• Heart disease
• Cancer
• Infection
• Liver disease
• Unknown causes

Pets often breathe rapidly while keeping their elbows away from their chest because expanding the lungs becomes difficult.

Pneumothorax

A pneumothorax occurs when air leaks into the chest cavity.

Common causes include:

• Trauma
• Bite wounds
• Ruptured lung tissue

The trapped air prevents the lungs from fully expanding.

Many pets require a procedure called thoracocentesis to remove the air.

Heart Disease

Many owners are surprised to learn that heart disease often presents as a breathing problem rather than a heart problem.

Here's why.

The left side of the heart pumps oxygen-rich blood to the body.

When it begins to fail, blood backs up into the lungs.

Pressure inside the lung blood vessels increases until fluid begins leaking into the air sacs.

This condition is called congestive heart failure.

As the lungs fill with fluid, oxygen exchange becomes increasingly difficult.

Your pet breathes faster because they are trying to compensate.

Common signs include:

• Resting respiratory rate increasing
• Exercise intolerance
• Coughing (especially dogs)
• Weakness
• Collapse
• Other Important Causes
• Heat Stroke

Heat stroke can rapidly progress to respiratory failure.

Panting becomes ineffective, body temperature rises, and multiple organs begin to fail.

This is a true emergency.

Severe Allergic Reactions

Swelling around the throat or airway may rapidly interfere with breathing.

These pets require immediate veterinary attention.

Anemia

Red blood cells carry oxygen.

When severe anemia develops, there may be enough air entering the lungs—but not enough red blood cells to transport oxygen throughout the body.

Affected pets often breathe rapidly despite having healthy lungs.

Pain

Pain can significantly increase breathing rate.

Examples include:

• Broken bones
• Abdominal pain
• Pancreatitis
• Severe arthritis
• Post-operative discomfort

However, pain should never be assumed to be the cause until more serious respiratory diseases have been ruled out.

Trauma

Traumatic injuries may cause multiple breathing problems simultaneously.

Examples include:

• Bruised lungs
• Bleeding into the chest
• Rib fractures
• Torn diaphragm
• Collapsed lungs

These pets require emergency evaluation even if they initially appear stable.

Dr. Rene's Clinical Pearls

🫁 Not every breathing problem starts in the lungs.

Many of the patients I treat have perfectly healthy lungs. Their difficulty breathing is caused by heart disease, airway obstruction, or fluid surrounding the lungs instead.

🫁 Rapid breathing is often your pet's first warning sign.

Owners frequently tell me, "They weren't coughing—they were just breathing faster." That subtle change is often the earliest clue that something serious is developing.

🫁 Flat-faced dogs should not struggle to breathe.

Many owners assume loud breathing is simply part of being a Bulldog or French Bulldog. While common, it should never be considered normal.

🫁 Cats often hide respiratory disease until they become critically ill.

If your cat is open-mouth breathing, don't wait to see if it improves. Cats have very little reserve once they reach this stage.

🫁 The cause determines the treatment.

Difficulty breathing isn't a diagnosis—it's a symptom. That's why finding the underlying cause is the most important step in helping your pet breathe comfortably again.