Tonsillar Squamous Cell Carcinoma in Dogs

 

A squamous cell carcinoma of the tonsils is an aggressive and metastatic tumor that arises from the epithelial cells of the tonsils. The epithelium is the cellular covering of all of the internal and external surfaces of the body, protecting the organs, inner cavities and outer surfaces of the body in a continuous layer of multi-layered tissue. The squamous epithelium is a type of epithelium that consists of the outer layer of flat, scale-like cells, which are called squamous cells. While all types of squamous cell carcinomas are invasive, carcinoma of the tonsils is particularly aggressive.

 

This type of tumor is highly invasive and local extension into the surrounding areas is common. This tumor also metastasizes to other areas of the body, including the nearby lungs and distant organs. As with other types of squamous cell carcinomas, middle-aged and older dogs are more commonly affected. In this case, the incidence is higher in dogs living in urban areas as compared to those in rural environments.

 

Symptoms and Types

 

• Difficulty with eating
• Difficulty swallowing (dysphagia)
• Breathing difficulties
• Bad breath (halitosis)
• Excessive salivation
• Oral discharge with blood
• Weight loss

 

Cause

 

• Exact cause unknown
• Ten times more common in dogs living in urban areas than those in rural areas

 

Diagnosis

 

You will need to give your veterinarian a thorough medical history of your dog's health and onset of symptoms. Your veterinarian will perform a physical examination, which will include a thorough examination of the lymph nodes in the neck area. Abnormally large lymph nodes are indicative of an immune system response to an invasion, but only a laboratory examination of the lymph node fluid and tissue will show the type of involvement. That is, whether the invasion is viral, bacterial, or cancerous in nature.

 

After the initial examination, your veterinarian will order routine laboratory tests, including complete blood count, biochemical profiles, and urinalysis. The results of these tests are usually normal in these patients unless some concurrent disease is present. Your veterinarian will take a biopsy from the lymph nodes to be sent to a veterinary pathologist. This tissue sample will be processed and analyzed microscopically for cancerous cells in order to reach a definitive diagnosis. Your veterinarian may also take X-rays of your dog's skull and thoracic regions to search for evidence of metastasis. Skull X-rays in some patients may show bone involvement -- where the tumor has spread into the bone -- and thoracic X-rays can help identify the amount of metastasis into the lungs.

 

Your veterinarian may also take X-rays of your dog's skull and thoracic regions to search for evidence of metastasis. Skull X-rays in some patients may show bone involvement -- where the tumor has spread into the bone -- and thoracic X-rays can help identify the amount metastasis into the lungs.

 

 

Treatment

 

Surgery may be used to perform an aggressive excision of the tonsils and affected tissue. However, most patients at the time of diagnosis are inoperable, either because of the location of the tumor, or the extent to which it has spread before its effects have been observed.

 

Removal of the affected lymph nodes may be conducted to prevent further spreading of cancerous cells, but it seldom provides a permanent cure. Radiotherapy may also be used in some patients, but its success has not been satisfactorily confirmed, so it is seldom used for these patients.

 

In cases where it is possible to operate and remove most of the affected area, the tumor and affected lymph nodes will be removed, and the surgery will be followed by radiation therapy and/or chemotherapy to prevent or slow down the spread of cancerous cells to other areas of the body.

 

Living and Management

 

Good nutritional support will be essential for ensuring the maintenance of your dog's body weight and condition. It is important to monitor your dog's food and water intake while it is recovering. After surgery, your dog will very likely not have much of an appetite, and will not want to eat or drink in great quantities. It may be necessary to temporarily use a feeding tube. In these cases you veterinarian will show you how to use the feeding tube correctly (placing it directly into the dog's stomach), and will assist you in setting up a feeding schedule.

 

After surgery, you should expect your dog to feel sore. To minimize discomfort, your veterinarian will provide you with pain medication for your dog. In addition, you will need to set up an area in the house where your dog can rest comfortably and quietly, away from other pets, active children, and busy entryways. Trips outdoors for bladder and bowel relief should be kept short and easy for your dog to handle during the recovery period. Use pain medications with caution and follow all directions carefully; one of the most preventable accidents with pets is overdose of medication.

 

Overall prognosis in affected animals is poor due to the aggressive nature of this tumor and frequency of metastasis to other body locations. Even with treatment, overall survival time generally is not more than several months. The decision to go forward with surgery or chemical therapy will be based on the actual prognosis. In some cases, end of life pain management may be in order.