There's a moment in emergency medicine I've never gotten used to — the one where you put your stethoscope on a dog's chest and hear almost nothing on one side. Learn more about respiratory health in dogs here. That silence is louder than any wheeze or crackle. It means something has displaced the air where air belongs, and whatever it is, we need to figure it out fast.
Lower respiratory disease is the category of problems that sits below the trachea — the bronchi, the lung tissue itself, and the pleural space surrounding the lungs. If upper respiratory conditions are the head colds of the pet world, lower respiratory disease is the pneumonia ward. The stakes go up. The diagnostics get more involved. And the window between "treatable" and "critical" can narrow without much warning.
Pneumonia: The Big Three Types
Pneumonia in pets falls into three main categories, and each one arrives differently.
Bacterial pneumonia usually follows a viral infection, immunosuppression, or some other insult that lets bacteria gain a foothold. Bordetella, Streptococcus, Pasteurella, E. coli, and Klebsiella are frequent culprits. The dog or cat develops fever, lethargy, rapid breathing, and a cough that sounds wet — like there's fluid rattling around in there. Chest X-rays show characteristic alveolar patterns, and the pet looks and feels sick in a way that's hard to miss.
Aspiration pneumonia is the one that keeps me up at night, because it can develop so quickly. It happens when food, liquid, or vomit enters the lungs instead of the stomach. Dogs recovering from anesthesia, those with megaesophagus (a condition where the esophagus loses its ability to push food down), and brachycephalic breeds are at elevated risk. I had a Bulldog patient named Tank who aspirated during a vomiting episode — his owner heard gurgling sounds an hour later, and by the time they reached the clinic, his oxygen saturation had dropped significantly. He pulled through after four days of hospitalization, but it was close.
Fungal pneumonia is geography-dependent and sneaky. Blastomycosis, histoplasmosis, coccidioidomycosis (Valley Fever), and cryptococcosis each favor specific climates and soil conditions. These infections can mimic cancer on X-rays, and I've seen cases where a pet was about to be started on chemotherapy before the fungal culture came back positive. The treatment course is long — months of antifungal medications — but the prognosis can be good when caught before the infection becomes disseminated.
Bronchitis and Airway Inflammation
Chronic bronchitis in dogs is defined as a daily cough lasting at least two consecutive months with no other identifiable cause. That sounds like a loose definition, and in some ways it is — it's a diagnosis of exclusion. The cough is dry to mildly productive, often triggered by excitement, exercise, or pressure on the trachea. Affected dogs are frequently middle-aged to older, and many carry extra weight.
I find the management conversation difficult because there's no cure for chronic bronchitis. The airway changes are permanent. But the symptoms are controllable in most dogs with a combination of weight management (this alone sometimes reduces cough frequency by half), environmental irritant avoidance, and intermittent or chronic bronchodilators and corticosteroids. Some dogs need a cough suppressant during bad stretches. The condition waxes and wanes, and I tell owners to expect good months and bad months.
Feline asthma is the cat counterpart, sort of, though the mechanism differs. It's an allergic airway disease that causes bronchospasm — sudden narrowing of the airways. Cats wheeze, cough (that hairball-like crouch), and during severe episodes can develop acute respiratory distress. About 1 to 5 percent of cats are affected. Inhaled corticosteroids delivered through a feline-specific spacer device have changed my approach to this condition dramatically — the systemic side effects are much lower than oral steroids, and compliance is better than you'd expect once the cat gets used to the mask.
Pleural Space Disease
The pleural space is the thin area between the lungs and the chest wall. Normally it contains just a tiny amount of lubricating fluid. When things go wrong, that space fills with fluid, air, or worse — and the lungs lose room to expand.
Pleural effusion (fluid accumulation) has a long list of causes. In cats, the two biggest are heart disease and lymphoma. In dogs, heart failure, liver disease, and various cancers lead the pack. The physical exam finding is distinctive — diminished heart and lung sounds on auscultation, rapid shallow breathing, and sometimes a fluid wave you can feel when you tap the chest. Thoracocentesis (placing a needle or catheter to drain the fluid) provides both diagnostic samples and immediate relief. I've watched cats go from gasping to comfortable within minutes of removing 200 milliliters of fluid from their chest. It's one of the more gratifying emergency procedures.
Pneumothorax — air in the pleural space — happens after trauma (hit by car, bite wounds penetrating the chest wall) or spontaneously when a bleb (a small air-filled blister on the lung surface) ruptures. The lung partially or fully collapses on the affected side. Emergency treatment involves removing the trapped air, and some cases require a chest tube or surgery.
Pyothorax (pus in the pleural space) is a serious bacterial infection that requires drainage, lavage, and prolonged antibiotics. It's more common in cats, often from bite wounds that introduce bacteria into the chest, though many cases have no identifiable origin.
What Diagnosis Looks Like
I start every respiratory case with a thorough physical exam and auscultation, but lower respiratory disease almost always requires imaging. Chest radiographs are my first step — they reveal patterns. An alveolar pattern (fluffy white areas replacing normal lung texture) suggests pneumonia or hemorrhage. A bronchial pattern (thickened airway walls creating "donuts" and "tramlines") points toward bronchitis or asthma. Pleural effusion shows up as a ground-glass opacity that obscures the heart silhouette.
When X-rays aren't sufficient, CT scans provide much more detail. I've found CT particularly useful for identifying lung lobe consolidation, mediastinal masses, and distinguishing fungal granulomas from neoplasia.
Sampling the airways — through a transtracheal wash or bronchoalveolar lavage — lets me look at the cells and organisms actually present in the lower airways. This is how I confirm eosinophilic inflammation (supporting an asthma diagnosis), identify specific bacteria for targeted antibiotic therapy, or occasionally find neoplastic cells.
Blood work rounds out the picture. Elevated white blood cells with a left shift suggest active bacterial infection. Eosinophilia supports allergic or parasitic disease. Coagulation panels are relevant when hemorrhage is a concern.
Treatment Principles
Treatment for lower respiratory disease is cause-specific, but some principles cut across conditions.
Oxygen supplementation is the immediate priority for any pet in respiratory distress. Before we have a diagnosis, before we have X-rays, if the pet can't oxygenate, we provide oxygen — via flow-by, nasal prongs, oxygen cage, or mask.
Antibiotics for confirmed or strongly suspected bacterial infections, guided by culture and sensitivity when possible. Empiric broad-spectrum coverage is appropriate while waiting for culture results in seriously ill patients.
Bronchodilators — terbutaline, theophylline, albuterol — open constricted airways and are the first-line rescue drugs for feline asthma attacks.
Anti-inflammatory therapy — corticosteroids primarily — reduces airway inflammation in asthma, chronic bronchitis, and some forms of pneumonia where excessive inflammation is causing harm.
Drainage procedures for pleural space disease. Sometimes a single thoracocentesis is enough. Other times, a chest tube stays in place for days.
The part I always emphasize to owners: respiratory disease treatment often works in stages. The initial stabilization might look dramatic — and it is. But the follow-up care, the recheck X-rays, the medication adjustments, and the home monitoring determine long-term outcomes.
Frequently Asked Questions
How is pneumonia in pets treated?
Bacterial pneumonia requires antibiotics — ideally chosen based on culture and sensitivity testing of airway samples. Supportive care includes intravenous fluids, nebulization and coupage (a technique where you rhythmically pat the chest to loosen secretions), oxygen supplementation if needed, and nutritional support. Mild cases can sometimes be managed outpatient with oral antibiotics and close monitoring. Severe cases need hospitalization. Recovery takes two to four weeks on average, with follow-up X-rays to confirm resolution.
Can my pet's bronchitis be cured?
Chronic bronchitis in dogs is manageable but not curable. The structural changes in the airways are permanent, and the goal of treatment is controlling symptoms and slowing progression. Weight loss, avoiding airway irritants (smoke, strong chemicals, dusty environments), and medications as needed keep most dogs comfortable. Some dogs have long stretches with minimal coughing, punctuated by flare-ups during weather changes or respiratory infections.
What's the difference between a heart cough and a lung cough?
This is one of the harder clinical distinctions, and honestly, they overlap. A cough from heart disease (usually left-sided heart failure pushing fluid into or around the lungs) tends to worsen at night and during rest, may be soft or moist-sounding, and is accompanied by increased respiratory rate. A cough from primary lung disease often worsens with activity or excitement and may be dry and harsh. But plenty of patients have both conditions simultaneously — an older dog with both chronic bronchitis and early heart disease isn't unusual. Chest X-rays and sometimes echocardiography help sort it out.
Should I be concerned about lungworms?
Lungworms affect dogs and cats in various parts of the world and are often underdiagnosed because they're not on every clinician's radar. Angiostrongylus vasorum in dogs and Aelurostrongylus abstrusus in cats can cause coughing, exercise intolerance, and coagulopathies. Dogs that eat slugs and snails are at particular risk. If your pet has a chronic cough that doesn't respond to standard treatments, ask your vet about fecal testing for lungworm larvae — it's a simple test that's sometimes overlooked.