Bronchitis in Dogs

What we know as asthma is actually called chronic bronchitis. Below, we'll talk about this lower-airway respiratory problem in dogs, which can also involve fibrosis.

It's important to know that when a dog's breathing is compromised, their life is at risk. That's why it's necessary to see the vet to treat any recurring symptom.

A dog's lungs

Before talking about asthma or chronic bronchitis, it's important to have some basic knowledge of a dog's lung structure, so we can understand how this condition affects them.

The lungs are part of the lower respiratory tract and are made up of two bronchi (the trachea splitting into two main bronchi), which branch into progressively narrower passages called bronchioles. These, in turn, end in the alveoli, which is where gas exchange — oxygen and CO2 — finally takes place.

Introduction to chronic bronchitis

Chronic obstructive pulmonary disease, or chronic bronchitis, is a progressive disease whose main symptom is a chronic cough (lasting at least two months). It covers two nearly indistinguishable conditions: chronic bronchitis and pulmonary fibrosis. It's an insidious disease characterized by barely reversible airway obstruction, with no other concurrent disease present.

What causes chronic bronchitis?

The cause isn't well defined, and it likely has multiple contributing factors. These factors can be genetic in small or brachycephalic breeds.

Inhaling smoke, such as tobacco smoke or air pollution, and certain allergens can contribute to inflammation, especially when the dog is continuously exposed to them.

Chronic infections, for example with the bacterium Bordetella bronchiseptica involved in kennel cough, can also predispose a dog to developing this disease.

Which dogs can get chronic bronchitis?

Middle-aged and older dogs (five to ten years old) are more affected. It occurs especially in small or toy breeds (Yorkshire Terrier, Cocker Spaniel, Poodle, Pomeranian, Dachshund) and obese animals. These breeds are also predisposed to tracheal collapse and mitral valve disease.

Symptoms in dogs with chronic bronchitis

Dogs with bronchitis or pulmonary fibrosis will show specific symptoms that help the vet diagnose the disease.

1. A harsh, dry cough that persists chronically, for at least two months. It may or may not be productive (bringing up secretions). It'll be more common in the early morning hours. Coughing fits can end in retching, sometimes with vomiting.
2. Progressively worsening exercise intolerance.
3. There can be excess mucus production, or mucopurulent discharge.
4. Respiratory dyspnea (difficulty breathing).
5. In severe cases, breathing is compromised even while the dog is resting. Cyanosis can appear — a bluish coloring of the mucous membranes from lack of oxygen — along with fainting.

How is chronic bronchitis diagnosed?

When our dog has a cough, the vet will take a general medical history, along with a general physical exam of the animal.

Lateral and dorsoventral chest X-rays will be needed to assess the state of the lungs and bronchial branches. Bloodwork will be done if the vet recommends it, to check the pet's general and systemic condition.

Another useful test is bronchoscopy, where inflamed airways can be seen along with a large amount of thick mucus.

A bronchial or bronchoalveolar lavage can also be done, using saline and then aspirating it back to collect cells from the bronchi and bronchioles, in order to run a lab analysis of them afterward and set up the right treatment based on the results. These last procedures require the dog to be sedated or anesthetized.

Treatment

Treatment is aimed at reducing airway inflammation and easing the clinical signs from inflammation, excess mucus, bronchial smooth muscle constriction, and dilation. Preventing secondary bronchopneumonia will be key to treatment.

Treatment will vary. Cough suppressants such as codeine are indicated for the cough, mucolytics such as bromhexine to help clear mucus, and bronchodilators such as theophylline.

Corticosteroids are useful since they reduce coughing and inflammation. Examples include methylprednisolone or prednisone. Antibiotics will be needed if there's symptomatic and diagnostic evidence of infection, using ones that are effective and reach an adequate concentration in the airways. Examples include amoxicillin-clavulanic acid, cephalosporins, or fluoroquinolones.

What is the prognosis for chronic bronchitis?

These dogs' general condition and physical exam are usually good. However, a sick dog who doesn't receive treatment will keep getting worse, and the disease will progress into the lungs.

What's more, a chronic cough can affect the pulmonary alveoli, filling them with fluid and causing atelectasis (lung collapse), which makes breathing much more difficult. So, as soon as we notice symptoms of this or any other disease, we need to see our trusted vet so they can start prompt treatment, for our pet's wellbeing.

Once the disease is diagnosed and effective, prompt treatment is started, how the dog responds varies. So we find some animals whose condition practically resolves, while others need ongoing medication adjustments.

Deterioration will be greater if the condition is complicated by secondary infections. So, the long-term prognosis is more guarded.

Tips for caring for a dog with chronic bronchitis

Generally speaking, at home we can follow a series of measures to eliminate, or at least minimize as much as possible, the factors that contribute to this disease's typical symptoms:

• In predisposed breeds like those mentioned above, get routine vet check-ups, especially for respiratory conditions.
• Keep the house clean so dust doesn't build up.
• Don't smoke around the dog, or let them stay in rooms with smoke.
• Keep them calm, without stress or anxiety.
• Walk them with a harness.
• If they're overweight, put them on a diet following the vet's instructions. This greatly improves ventilation, increases lung capacity, reduces the cardiorespiratory workload, and improves arterial oxygenation.