71 | The step-by-step guide to managing lower airway disease in dogs as a veterinary nurse

PodcastRespiratoryNursingEmergency and Critical Care
Written By Laura Jones

Today, we’re following up on last week’s feline focus and looking at lower airway diseases in our canine counterparts.

 

We might not see them as often, and they might appear more stable - well, most of the time - but these cases are anything but boring, requiring lots of nursing care, both in the clinic and long-term.

Just like our asthmatic cats, it’s good quality nursing that makes all the difference, and to give that great care, we need to understand the lower airway diseases we see, and their impact on our patients, which is precisely what we’re covering in this episode.

Lower airway diseases in dogs - which do we see, and why?!

Unlike cats, where asthma dominates the conversation, dogs have a different mix of conditions that fall under the lower airway disease umbrella. These include:

  • Chronic bronchitis (yes, dogs get this too)

  • Bronchomalacia (airway collapse - think tracheal collapse, but lower down)

  • Less commonly, parasitic infections (like lungworm)

  • Inflammatory or allergic airway diseases (like eosinophilic bronchopneumopathy)

The term "chronic bronchitis" is used most frequently. But, just like with cats, it’s not one-size-fits-all, and many of these conditions overlap.

What is canine chronic bronchitis?

Chronic bronchitis in dogs is characterised by a persistent cough present for at least 2 months, without any other identifiable underlying cause.

We don’t know exactly why it happens. Still, we know this - it’s a non-infectious, inflammatory disease of the lower airways causing chronic airway inflammation, excessive mucous production and neutrophilic inflammation, just like our chronic bronchitis cats. 

Over time, that persistent inflammation causes the airway walls to become thickened and narrow. This makes it harder for the dog to move air efficiently and irritates the airways, leading to a persistent, hacking cough. 

Their lungs are stuck in a vicious cycle - the inflammation causes coughing, the coughing worsens the inflammation, and round and round we go.

The longer this cycle continues, the more permanent airway damage becomes. Lung function progressively declines, leading to irreversible changes like fibrosis and airway collapse.

Which patients are at risk?

We see CCB in older, small-breed dogs such as Pomeranians and Chihuahuas. 

Cocker Spaniels are also predisposed since they have a higher risk of developing bronchiectasis, which is airway dilation secondary to inflammation and damage to the bronchial wall. 

Bronchiectasis and chronic bronchitis go hand-in-hand, so it’s common to see bronchiectasis in dogs with chronic bronchitis.

Other potential factors include exposure to environmental odours and perfumes, as well as cigarette smoke, and obesity.

Sound familiar? Environmental triggers and body condition are crucial in canine airway disease, not just in our asthmatic cats.

Ok, so that’s what CCB is. But what clinical signs do we see?

Our chronic bronchitis dogs usually present with:

  • A chronic, harsh, dry cough (sometimes described as "goose-honking" if the patient has secondary airway collapse)

  • Exercise intolerance

  • Occasional tachypnoea or mild dyspnoea, especially after excitement

  • Gagging or retching

  • And potentially, signs of respiratory distress in severe cases.

Unlike feline asthma, dogs are less likely to have sudden acute decompensations, but that doesn’t mean it never happens - so be ready if one of these patients arrives as an emergency!

What about bronchomalacia?

Just like tracheal collapse, we can see structural changes to the smaller airways. The cartilage rings that line the trachea and hold it open continue down into the bronchi and bronchioles, and if these cartilages weaken they too can collapse.

This might be a primary cause for the patient’s lower airway signs, or it could occur secondary to chronic airway inflammation, like in our bronchitis patients.

The mechanical irritation from the collapsed bronchi causes further coughing, which causes further airway irritation and inflammation, remodelling, and worsening collapse.

Just like chronic bronchitis, these patients can end up in an ongoing cycle of coughing and inflammation, so stopping the coughing cycle is really important.

And then there’s infection…

For the purpose of this episode, I’m going to focus on probably the biggest and most problematic infection causing coughing and respiratory signs in our patients - lungworm.

What is lungworm?

Lungworm is an inflammatory disease of the lower airways caused by a variety of worm species - commonly Angiostrongylus vasorum, though there are lots of others, too!

In A. vasorum infection, eggs produced by adult females enter the pulmonary arterial circulation, where they moult into L1 larvae. These migrate from the blood vessels into the bronchi, where they are coughed, swallowed and passed in faeces.

After an intermediate host ingests the L1 larvae, the larvae undergo further moulting until they are ingested by the patient. The larvae mature and migrate to the heart, where they lay eggs, and the cycle continues. Despite the name ‘lungworm’, the worms don’t actually live IN the lungs - but they have a significant impact on them, and their larvae, of course, migrate into the bronchi for elimination as part of their life cycle.

What problems does lungworm cause, and what signs do we see?

The immune system reacts to the presence of the adult worms, causing marked immunological and inflammatory reactions. This leads to haemorrhage, pneumonia, pulmonary oedema and even fibrosis. 

Patients can present with a variety of clinical signs, from tachypnoea and coughing to dyspnoea and bleeding disorders.

Ok, that’s three of our lower airway diseases explained - what about allergies?!

Inflammatory/allergic airway diseases are common in dogs, though their exact cause is often unknown. 

One such disease is eosinophilic bronchopneumopathy or EBP - a disease somewhat similar to feline asthma, in that eosinophils infiltrate the bronchi and lungs due to a hypersensitivity (allergic) reaction.

The role of inhaled allergens in this specific disease is unknown, but reported sensitivities in patients with EBP include moulds, bacteria, parasites, fungi and even certain drugs.

It’s usually seen in young adult dogs, and particularly large breeds. Siberian huskies and Alaskan malamutes are predisposed, and it’s commonly reported in Labradors, Rottweilers, and German Shepherd dogs.

And what signs do we see in EBP patients?

Coughing, gagging and retching are very widely reported. 

Patients may be relatively stable on presentation, or present in respiratory distress if they have severe airway inflammation and mucous production impacting airflow, with signs such as tachypnoea, dyspnoea and orthopnoea.

Nasal discharge may also be seen, though less commonly.

So that’s the common lower airway diseases we see - what’s our next step?

Just like our cats, we need a stepwise approach when managing these patients - and as nurses and technicians, we’re highly involved throughout. This starts at initial presentation with rapid triage and stabilisation, continues through the patient’s diagnostics and in-hospital care, and finishes with ongoing client advice and support.

Step one: Stabilising the respiratory distress patient.

If your patient presents in respiratory distress, it’s always best to stabilise first and see what’s causing the problem later.

This means minimal handling, sedation (butorphanol, ACP or even low-dose dexmedetomidine are often used, depending on the individual patient and the vet’s preference) and oxygen therapy (in a way that the patient tolerates).

Stressed dogs with lower airway disease can easily spiral, so it’s about keeping them (and us, and the ward!) calm, quiet, and settled.

And always be prepared to intervene if things deteriorate - have an emergency airway kit, IV kit, and emergency drugs within easy reach.

Step two: Performing and assisting with diagnostics.

Once our patient has stabilised (or if they’ve presented as a stable patient), it’s time to figure out what’s causing their signs. The good news is that there are a LOT of skills we can use during this process. They include:

  • Performing imaging - such as taking thoracic radiographs, CT, or even fluoroscopy depending on the individual patient and their suspected disease

  • Assisting with bronchoscopy to directly visualise the airways, and collect samples for cytology, culture and infectious disease testing

  • Performing or assisting with a bronchoalveolar lavage to look at the inflammatory cells present within the airway, and determine the underlying disease

  • Performing infectious disease testing to rule them out as a potential cause, or to confirm the patient’s diagnosis - such as the Angiostrongylus vasorum ELISA test, or a Baermann.

Step three: Nursing the patient effectively whilst they’re hospitalised.

There’s a lot to think about when treating and nursing these patients in the hospital. 

Whilst their exact treatment will vary depending on their underlying disease, we commonly use:

  • Steroids to manage airway inflammation

  • Bronchodilators (more commonly used in cats, though sometimes used in dogs)

  • Antibiotics but ONLY if a secondary infection is confirmed

  • Anthelmintics like fenbendazole to manage lungworm

And alongside this it’s all about good supportive care. Providing oxygen via the most appropriate method for the patient, giving them fluid therapy as needed to maintain hydration, performing special sense care to prevent drying of the eyes and mucous membranes in oxygen, and carefully monitoring the patient.

Step four: Supporting the patient and client with long-term management.

If this isn’t your first episode, you’ll know the drill by now - nurses are VITAL when supporting chronic medical conditions long term, and if your practices aren’t using you to do this, they (and their patients) are missing out.

Client support, education and guidance is essential. The long-term goals when managing canine lower airway disease include:

  • Weight management 

  • Environmental control (minimising exposure to potential allergens)

  • Medication administration, including inhaler training where needed (yes, dogs can use AeroDawg chambers!)

Chronic conditions like eosinophilic bronchopneumopathy and chronic bronchitis don’t go away, but with good management and nursing support, we can significantly improve quality of life for these patients.

Did you enjoy this episode? If so, I’d love to hear what you think. Take a screenshot and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!

References and Further Reading

Laura Jones
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