When you hear the words ‘lung cancer’ you might think of someone with a long-term smoking habit, but did you know that animals can also get lung cancer? The good news is that primary lung cancer is rare in dogs, but there are some key facts to be aware of if you own a four-legged friend.

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What is lung cancer?

By definition, cancer is ‘uncontrolled cell division’, this often results in a mass or tumour of cancerous cells. ‘Lung cancer’ is a broad term often used to refer to both primary and secondary (or ‘metastatic’) lung tumours, but these can behave quite differently. Let’s differentiate between them. Primary tumours are tumours that originate in the lungs. These are rare in dogs, but unfortunately when they do occur, the large majority are cancerous and can spread to other parts of the body such as the lymph nodes. Secondary tumours arise from a cancer somewhere else in the body that has spread to the lungs. This type of disease is more common than primary lung tumours. 

Which dogs are more likely to get lung cancer?

Older dogs over 10-years-old are at higher risk of developing a type of primary lung cancer called pulmonary adenocarcinoma but there is no particular breed of dog more likely to develop primary lung cancer than others. It is slightly different when it comes to metastatic disease, as the age at which a dog is more likely to develop this will depend on the risk of the primary cancer. So far, there is no definitive link between secondhand smoke and the occurrence of lung cancer in dogs (although it seems empirically likely – Ed.). 

What are the symptoms of lung cancer in dogs?

The symptoms shown by a dog with lung cancer will depend on whether there is one single lesion or multiple lesions. Some common symptoms of both include coughing, exercise intolerance, weight loss, difficulty breathing and lethargy. 

How can lung cancer be diagnosed?

The first step into investigating whether a dog has lung cancer will usually be chest x-rays, which may show lung tumours if they are present. For a confirmation of lung cancer, a sample of tissue called a biopsy will need to be taken. This may be done via placing a hole in the chest (thoracotomy); or by using an ultrasound scan to obtain a needle sample. If your vet has a strong suspicion your dog may have lung cancer, or if further diagnosis is needed, you may be offered referral to a specialist hospital; where they can carry out advanced imaging such as a CT scan which is a type of three-dimensional x-ray.

Treatment and prognosis

Treatment of lung cancer in dogs involves treating the primary tumour and using supportive treatment to help the patient feel better. Supportive treatment can include the use of medications to relieve coughing (antitussives), anti-inflammatories and in some cases antibiotics if there is an infection present. 

Depending on the type and number of tumours, surgery can be helpful in removing some of the cancerous material; especially if there a single tumour that can be completely removed. Vets can also prescribe chemotherapy to improve the survival times of animals diagnosed with cancer. The patient may need to be monitored with regular x-rays to track progression of the disease or check for recurrence. 

In short, some types of lung cancer may be treatable in dogs, but treatment mainly focuses on management and keeping the animal comfortable.

Prognosis really depends on the type of cancer that has been diagnosed. And whether a tumour is able to be completely or partially removed. Some small tumours without any wider involvement in the body can be treated and have a better prognosis. If the lung tumours are metastatic tumours (coming from another cancer elsewhere in the body) unfortunately the prognosis is poor. But many dogs can be kept happy and comfortable with medication for a number of months if this is the case.

I have noticed my dog coughing, should I be worried?

It’s important not to panic if you have noticed your dog coughing or displaying some of the symptoms above. There are lots of potential causes of coughing that can be much less serious; such as kennel cough, which is a short term respiratory infection and is very common. If you have noticed your dog showing any of the symptoms above you should contact your vet practice; they will be able to examine your pet and discuss any of your concerns.

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