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Non-Cancerous Lung Tumors in Dogs

Non-Cancerous Lung Tumors in Dogs

Having your dog diagnosed with lung cancer is scary and confusing. In fact, you might be left wondering if the diagnosis is even real. In many cases, dogs don’t have symptoms at all. In some cases, tumors are only suspected at a regular wellness check.

Unfortunately, tumors are difficult to diagnose and often don’t have a good prognosis.

If your dog has been diagnosed with benign lung cancer (adenomas), your head is probably spinning with information. At the end of the day, all you really want to know is whether your dog is going to be okay.

It’s confusing, but we’re going to make it a little easier to understand.

Primary tumors (the ones that don’t spread to other parts of the body) are rare in pets. That’s not really good news because if your dog is going to be diagnosed with a tumor, it’s the non-cancerous one that you want.

Unfortunately, secondary tumors (the ones that spread to other parts of the body) are more common than primary ones.

Now, if the veterinarian suspects any kind of cancer in your dog’s lungs, early diagnosis is key. Sometimes, the surgical removal of non-cancerous tumors in dogs help to improve the survival rate.

What’s The First Thing I Should Know About Non-Cancerous Lung Tumors in Dogs?

If your veterinarian has diagnosed a primary tumor, he/she is talking about the original tumor. It only becomes secondary when it has spread to other parts of the body.

Unfortunately, the tumor may not be diagnosed early enough to catch it before it spreads.

The reason for this is the lack of clinical signs. It’s thought that approximately 25% of dogs with primary tumors have no signs at all when they are diagnosed. The diagnosis usually happens as part of a routine exam.

Surgical Removal of Non-Cancerous Lung Tumors in Dogs

If your dog has been diagnosed with a rare, non-cancerous tumor, it might be possible to remove it with a simple outpatient procedure.

The exception is when the tumor causes difficulty breathing. This can happen if the tumor blocks the trachea. The other complication to surgery iis the development of paraneoplastic syndromes.

Paraneoplastic syndromes are a rare group of disorders that happen when cancer causes the immune system to attack its own white blood cells.

Slow Growing Non-Cancerous Lung Tumors in Dogs

Non-cancerous lung tumors are usually slow-growing.

They are less likely to metastasize to the lung tissues (metastatic lung cancer). Unfortunately, they are rare. A dog is much more likely to develop secondary tumors. This is where the prognosis becomes very poor.

Statistically, primary tumors are almost always cancerous.

three senior dogs in a picturePin

Dog Breeds More At Risk of Lung Cancer

Small, non-cancerous growths are sometimes seen in older dogs. As dogs age, their immune systems weaken. This can leave them more vulnerable to cancers and malignant tumors.

Breeds that may be predisposed to developing metastatic lung tumors include:

  • Australian Shepherds
  • Irish Setters
  • Bernese Mountain Dogs
  • Doberman Pinscher
  • Boxers

Symptoms of Lung Cancer in Dogs

Early signs of lung cancer in dogs can be vague or misdiagnosed. Some common signs include:

  • non-productive cough (nothing comes up)
  • weight loss
  • fatigue
  • labored breathing
  • poor appetite
  • exercise intolerance
  • rapid breathing
  • wheezing
  • vomiting
  • fever
  • lameness

Some dogs show no signs at all.

How A Diagnosis of Lung Cancer in Dogs is Made.

There are three methods commonly used to diagnose lung tumors or cancer in dogs: radiography, chest X-rays, and CT scans.

An abdominal ultrasound may also be used to examine the abdominal organs of your dog. This is used to help determine whether the cancer has spread or affected other organs.

Radiography

Radiography (or radiographs) uses a particular machine that projects a film and records every detail about the lungs.

This ensures that there is no tumor growth within the chest cavity, i.e., within the airways. If there is a tumor present, it will look differently from the surrounding normal lung tissue.

In some cases, it’s difficult to tell the difference between a cancerous tumor or a benign nodule. If the lesions are too small, they may not be visible.

In order for lesions to appear on the radiograph, they have to be at least 0.5 – 1.0 centimeters in diameter.

Chest X-rays

A chest X-ray image shows any changes in the size or shape of an airway of the lungs. When a tumor is present, the X-ray will show it as an area different from the surrounding normal lung tissue.

All tumors are different in appearance. For example:

  • They can be simple or complex in their structure
  • They can be solid masses
  • They may have an empty cavity,
  • Tumors can be round, oval, or irregularly shaped.

A chest x-ray could detect a solitary pulmonary nodule in the lungs.

Computerized Tomography (CT)

The third diagnostic method for non-cancerous lung tumors is computerized tomography (CT).

A CT scan provides more detail than a standard X-ray and is much faster to get than an MRI. You can use it to diagnose any problems in the lung, from simple changes to the airways to a lung tumor.

Treatment Options

If the tumor is slow-growing and unlikely to spread, the veterinarian may recommend surgical removal of the affected lobe.

In that case, you may be referred to a board-certified veterinary internal medicine specialist. Before recommending surgery, the specialist may perform a fine needle aspiration to gather cells from the lungs.

This is a minimally invasive procedure. The cells obtained are examined by a pathologist to try and make a definitive diagnosis before surgery is attempted.

When surgery is recommended the process could include:

  • Complete removal of the affected lobe
  • Removal of a portion of the lung
  • Use of a scope to have a look at the lob and obtain a piece of affected tissue through a smaller incision.

Chemotherapy Treatment

In some cases, primary lung tumors can’t be removed completely. Reasons for this could be due to the tumor’s location or the risk of spread.

Chemotherapy can be expensive and offers no guarantee. However, the specialists involved in your dog’s care will be able to give you the best recommendation.

There is some risk of side effects that could include:

  • nausea
  • anemia
  • hair loss
  • mouth sores
  • dehydration

Despite the list of possible side-effects from chemotherapy, the reality is the many dogs have very few side-effects. They tend to be better off than their human counterparts.

In the end, it is up to the owner whether to pursue these options. If the owner and the veterinarian agree, they can choose the best option to pursue.

The following treatment options are available for non-cancerous lung tumors:

Radiation Therapy

Radiotherapy is a well-proven treatment option for non-cancerous tumors and is also used to treat primary lung cancer, for example, pulmonary carcinomas (most common).

The procedure involves implanting a radioisotope (a type of chemical that will eventually decompose) into the tumor and then directing radiation.

When the radioisotope decays and disappears from the body over time, the radiation kills any remaining cancer cells too. The most common treatment for bronchial adenomas is table radiotherapy using COSI or Synarc XRT.

In some cases, the tumor may be so large that it may not be possible to remove it surgically.

If that happens, radiotherapy may reduce tumor size and help prevent the tumor from growing larger. A small amount of radiation is used to kill living cells and make them unable to grow.

Immunotherapy

A third option is an immunotherapy. In this treatment, particular immune-stimulating substances are introduced to help the body mount an immune response against the tumor.

This treatment can shrink lung tumors and prevent them from growing.

The goal is to stimulate a good immune response against the tumor or slow down its growth.

Senior dogPin

Surgery

The fourth treatment option for non-cancerous tumors is the surgical removal of the tumor. If the tumor has not grown in size, surgery may be an option. This can be done as a major operation or as a minor operation.

If the dog’s health is too poor for a major operation, then a chest tube could be placed and used to treat pleural effusion by draining any fluid that collects in the thoracic area (chest) of the lung or around the heart.

This will reduce the pressure in the airways and may help prevent further problems.

This approach can provide excellent results, especially when the tumor sits in the airways and blocks airflow.

Surgery can also effectively tackle larger tumors blocking or impinging on the trachea and bronchi (airways).

For example, sarcomas of the chest wall affecting Bernese mountain dogs, which cause difficulty breathing, can often be removed using minimally invasive surgery techniques such as thoracotomy.

Squamous cell carcinoma can also be treated using surgery.

When discovered early enough, histiocytic sarcomas can be surgically removed without causing any damage to the surrounding tissue.

Interferon Therapy

The sixth treatment option for non-cancerous tumors is interferon therapy, which stimulates the body’s immune system to attack cancer cells.

It has been used in people and dogs with lung tumors, and it seems to have some effect on inhibiting tumor growth.

However, its use has not been widespread partly because of its high cost. Its effectiveness is improving, and it may become a more acceptable treatment method in the future. However, this treatment option should not be used if the tumor is too large.

Cytotoxic Chemotherapy

In some cases, surgery and other treatment options do not provide enough of an improvement to the quality of life for the dog.

In this case, a clinical trial involving cytotoxic chemotherapy with or without radiotherapy may be suggested.

The goal is to kill all cancer cells in the tumor before the dog goes into remission.

It can be very effective at reducing tumor size and duration of treatment. Of course, there is no guarantee. The best case scenario is that It improves the dog’s chance of survival and overall quality of life.

Mast cell tumors that occur underneath the dog’s skin can be treated through this process.

No Treatment

In other cases, the best treatment option for a non-cancerous lung tumor may be to choose not to treat.

The owner may decide that surgery would add more suffering or that treatment might not work as expected. The choice may also be based on cost or other factors involved in treatments.

The dog’s quality of life should always be considered when looking at treatment options.

Photodynamic Laser Therapy

Photodynamic laser therapy uses specific optical wavelengths of light to destroy cancer cells and tumor tissue.

For example, it could kill bronchial and lung tumors by using laser light with a wavelength of 607 nm. This treatment option is usually only administered in an operating room under the supervision of a doctor.

Broncho Pulse Irradiation

A new device known as “Broncho Pulse Irradiation” works by circulating cold oxygenated blood through the tumor area, then irradiating the tumor with a low level of high-energy x-rays.

The effect destroys tissue but keeps the dog’s surrounding healthy tissue intact.

The typical side effects of radiation therapy include:

  • fatigue
  • loss of appetite
  • loss of hair/fur

In some cases, medication can address these side effects. Dogs who have allergies may experience increased allergy symptoms due to radiotherapy.

Median Survival Time

The prognosis for dogs with low-grade (small) lung tumors depends on whether there is lymph node metastasis. If the cancer has spread into the lymph nodes, the average survival time is approximately 16 months. This time span may be increased if surgery is performed.

Sadly, the prognosis for dogs with high grade tumors that also include lymph node involvement is only 3 months.

Keep in mind that every dog is different and every tumor is different. These timeframes are not absolute.

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Summary

The most important factor affecting the decision-making process is the dog’s quality of life and comfort. Deciding on the best treatments while deciding on whether to euthanize or not is gut-wrenching. I wish you all the best in your journey.

Working together with a trusted veterinarian and other veterinary specialists offer your dog the best option for survival.

Please note: This post was not intended as medical advice. Always seek the professional opinion of a licensed veterinarian.

                        
                   

Sources:

vcacanada.com-know-your-pets-lung tumors

merck veterinary manual

Northeast Veterinary Hospital

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