Coughing canines

At this time of year, coughs and colds affect us all, and the TV adverts regularly promote remedies to help suppress or treat the symptoms. Unfortunately, a chronic cough is not only an irritation, but it can also be quite debilitating. Our patients are also affected by this problem, and it’s our job to help them.

Posted: 11 February 2019

Coughing canines

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Chronic bronchial disease in dogs can be difficult to diagnose as it’s often complex in nature. The condition also changes with time, slowly deteriorating in the absence of help.

Look for the clues of chronic bronchial disease

When your patient arrives, be alert to the chronic syndrome if you see some of these signs;

  • Mucus – particularly if you find an excessive production in the upper airways
  • Coughing – frequent, persistent and at times uncontrolled, violent and spasmodic
  • Expiratory click – it’s occasionally possible to hear a loud click when checking the respiratory system. This would be heard at the end of expiration and is caused by the airway collapsing
  • Distress – collapse of the upper airway architecture can make an animal anxious or­­­­ panic
  • Collapse – at times where the airways become obstructed, the dog may even suffer from episodes of syncope

Which dogs are at risk?

  • Over 5’s – whilst there doesn’t seem to be a specific age predisposition, the chronic cough is more common in dogs over the age of 5 years. Younger dogs are rarely affected
  • Obesity – any dog which is overweight will be more at risk
  • Dental disease – chronic bronchial disease and coughing is more prevalent in animals with advanced dental/periodontal disease
  • Toy breeds – small breeds of dog, such as toy Poodles, Yorkshire Terriers, Chihuahuas and Pomeranians, are more frequently affected

Diagnosis can be challenging

We need to use all the tools in our clinical armoury to make an accurate diagnosis. So often the chronic coughing dog is just treated symptomatically, but it makes sense to try to find the cause.

A. Radiography

Ideally, you’ll take lateral and dorso-ventral views of the chest, with the lungs positively inflated. It’s usually best to do this with the animal intubated and under general anaesthesia. Look for the typical presentation, which includes;

  • Interstitial pattern - this will be in the early stages of disease
  • Doughnuts and tram lines – look carefully for the bronchial changes which develop. These are as a result of thickening of the bronchial walls. The end on bronchi appear as doughnut rings, and the longitudinal sections of the bronchi appear as tram lines. Don’t confuse age related bronchial calcification with inflammatory bronchitis

B. Bronchoscopy

Many of us have access to flexible endoscopes, but how often do we include them in our general work-up? It can be quite daunting to use one if you’re unfamiliar with the procedure, so if you find that you need a bit more confidence and experience, why not sign up to a practical CPD Endoscopy course. Some of the manufacturers and suppliers will also run them.

By using the smallest flexible bronchoscope, take a look at the trachea and both left and right bronchi. The key features to identify with chronic bronchial disease are;

  • Mucus – this is often thick and tacky
  • Colour changes – the smooth pale bronchi take on a mottled white and pink appearance

C. Broncho-alveolar lavage

A bronchial wash or bronchoalveolar lavage (BAL) can help to establish a definitive diagnosis in lower airway respiratory conditions. Ideally this is done using the guidance of an endoscope, as it will produce a more accurate diagnosis.

Treating chronic bronchial disease

Be realistic

With a diagnosis of chronic bronchial disease, it’s important to set a realistic expectation for your clients. Make sure they understand that the treatment you offer is aimed at controlling the condition. They need to appreciate there isn’t a cure.

A. In the acute phase

If your patient is presented in acute respiratory distress, perhaps showing signs of hypoxia, cyanosis or even collapse, the emergency supply of oxygen is essential. Sedation may be required if the animal is conscious and distressed. In some cases, you may need to consider a short acting anaesthetic to enable you to place an endotracheal tube.

B. Long-Term Management

Corticosteroids – most dogs will benefit from the use of corticosteroids to control inflammation. These can be initially given as injectables (e.g. methyl prednisolone). Oral glucocorticosteroids will also provide an effective anti-inflammatory effect, whilst also providing support by virtue of their antitussive properties. Aim to use the lowest effective dose possible for the shortest period of time.

Antibiotics – whilst bacterial infections are relatively uncommon with chronic bronchial disease, there are some opportunistic organisms which can be problematic, requiring antibiotics. For example, B. bronchiseptica can be a complication and mustn’t be underestimated. It can start as a low-grade infection in the small airways but can also progress to cause pneumonia. Antibiotics which are frequently used include doxycycline, enrofloxacin, amoxycillin & clavulanic acid, ampicillin and erythromycin. As always with any suspected bacterial infection, it’s best to culture and identify before treating.

Bronchodilators – restricted airways create a major problem with oxygen delivery. Often the narrowing of the airways is caused by bronchoconstriction, so the use of bronchodilators is often necessary. These can be given orally (e.g. propentofylline & theophylline) or by inhalation (e.g. terbutaline, salbutamol and albuterol) using an aerosol inhaler. With any unlicensed drugs, always check and prescribe under the rules of the cascade.

Nebulisation – this will offer some real help to patients with acute symptoms. The excessive accumulation of bronchial and tracheal mucus, and those with secondary bronchial infections, will have airways which are difficult to clear. The moist aerosol will help to make the mucus more fluid and therefore easier to remove via the action of cilia. Antibiotics and bronchodilators can also be delivered in this form. Use 5 to 10mls of sterile saline (with or without supplementary drugs) at least 3 to 4 times daily for 15 to 20 minutes. If you don’t have a nebuliser in your practice already, it’s worth considering getting one. They aren’t expensive and can really help.

What is the long-term prognosis?

Dogs presented with a chronic cough will often be diagnosed as having chronic bronchial disease. In most cases, the disease is life-long, and treatment will be aimed at alleviating the signs, and at most delaying the progression. Remind your clients that you cannot cure this condition, however the results of effective treatment can be rewarding and can offer an excellent quality of life for many years.

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