Many types of Lung tumors in dogs can occur in the different parts of the respiratory system including the lungs. Some of the commonly occurring tumors are explained below.
Tumors of the Nose and Sinuses
Nose and sinus tumors are not very common in dogs, accounting for only one to two percent of all the tumors occurring in dogs. But when they do occur, almost all of them are cancerous. Older dogs above 10 years of age are more susceptible to nose and sinus tumors. They occur more often in males and in breeds with longer noses than in females and short-nosed dogs. If the cancerous tumors are not diagnosed early and treated aggressively, the survival time is limited to a period of 5 months or less.
The typical symptom of these tumors is a chronic discharge from the nose. It may contain blood or pus along with mucus. The discharge may begin from one nasal opening initially, but soon both sides may become involved. Bouts of sneezing, nosebleeds and snoring are other common signs. When the bones and cartilages in the nasal passage and the sinuses deteriorate with the progression of the disease, facial deformities may become apparent. When the tumor spreads to the area beneath the eyeballs, they may protrude and tear production may become excessive. The corneas may become inflamed and the dog may become blind. If the tumor grows into the upper portion of the skull, symptoms of central nervous system involvement begin to appear. The dog may become disoriented and suffer from seizures. It may fall into a stupor, followed by coma.
Initial diagnosis of nose and sinus tumors in dogs may be based on the symptoms and medical history. X-rays and CT scans may give a better picture of the sinuses as well as the nasal cavity. They may reveal signs such as increase in density or evidence of bone deterioration. CT scans give a more detailed picture and help in differentiating between tumors and other obstructions that may precipitate similar symptoms. Testing of a sample tissue extracted from the tumor (biopsy) can confirm the diagnosis.
Different types of tumors require different treatment regimens. The veterinarian may consider the type of tumor and its extent when deciding on suitable treatment. Excision of the tumor, radiation and chemotherapy are the options available. They can be combined for a better outcome. Early detection and aggressive treatment may help control the disease.
Tumors of the Larynx and Trachea
In dogs, laryngeal and tracheal tumors are not very common. When they do occur, their symptoms are similar. Respiratory problems like chronic cough, difficulty while inhaling air, breathing difficulty following light exercise and breathing with a high-pitched noise are the usual symptoms. Respiratory difficulties are in direct proportion to the extent of airway obstruction caused by the tumor. The dog’s bark may become hoarse or it may lose its voice altogether. In some rare cases, the dog may even bring up blood while coughing.
When symptoms indicative of obstruction in the upper respiratory tract are observed, other possible causes are first eliminated before a diagnosis of laryngeal and tracheal tumors is considered. An endoscopic examination by the veterinarian may reveal the abnormal mass in the respiratory tract. This is followed by a biopsy to confirm the diagnosis. Surgical removal of the mass is the treatment of choice. Radiation may be effective in treating certain types of tumors.
Primary Lung Tumors
These timorous growths begin in the lung tissues. Primary tumors in the lungs are not very common in dogs. They constitute about 1% of all the different types of tumors in dogs, even though they are encountered more often in recent years. It is not clear whether this is because of earlier detection due to increased awareness or more frequent exposure to carcinogens resulting in more incidences. Since dogs aged 10 years and above are more susceptible to primary lung tumors, general increase in the lifespan of pets may be a factor too. Almost all the primary lung tumors detected in dogs are malignant. Both males and females are affected equally irrespective of their breeds.
The symptoms of primary lung tumors may vary according to their location and rate of growth. Other lung diseases may contribute to their severity too. Chronic cough and other signs of respiratory distress such as wheezing, rapid and shallow breathing and difficulty to breathe are usually present. Lack of appetite, regurgitation of food and vomiting are common, and may result in weight loss and lethargy. The dog may have intolerance to exercise and may even become lame. However, constantly high body temperature and a dry cough are the typical indications of primary lung tumors.
When the dog displays symptoms indicative of lung tumors, x-ray examination of the chest is done. If lung cancer is suspected, a biopsy of the tumor tissue is taken for laboratory testing.
Surgical removal of the tumor along with the affected portion of the lung is the most preferred treatment. But in cases where surgery is not feasible or when the tumor has become widespread, chemotherapy is the next option. If the dog has only one primary lung tumor without any lymph node involvement, the expected survival time is between 15 months to 2 years. But if lymph nodes are affected, or if there are more than one tumor, the dog may not survive as long. Mortality rate is higher when the tumors recur or when they spread to other areas.
Metastatic Lung Tumors
When tumors that occur elsewhere in the body spread to the dog’s lungs, they are called metastatic lung tumors. The tumor cells may reach the lungs via blood vessels or lymph ducts, or they can directly spread from a tumor in the chest area. Metastatic tumors in the lungs may have the same symptoms as the ones displayed by primary lung cancers, even though coughing may not be as pronounced. Depending on where the tumor is located, and the number of lesions present, the intensity of the other symptoms may vary too. When metastatic tumors are detected, they are treated in the same way as primary lung cancers. If surgical removal is not feasible, radiation and chemotherapy may be considered. Since metastasis generally occurs in the later stages of a malignant tumor present in some other location, the prognosis is often very poor.