Oral squamous cell carcinoma (OSCC) is a prevalent and aggressive oral cancer in dogs. Recognizing its signs and seeking timely veterinary intervention are important, as early detection and appropriate management significantly influence outcomes.
What is Oral Squamous Cell Carcinoma?
Oral squamous cell carcinoma is a malignant tumor that originates from the squamous cells, which are flat cells lining the surface of the mouth. This type of cancer is the second most common oral tumor in dogs, following melanoma. OSCC lesions often appear as irregular, raised, or cauliflower-like masses that can be pink or red and may ulcerate or bleed easily.
These tumors commonly develop on the gums, particularly around upper teeth, and sometimes under the tongue or on the tonsils. OSCC is highly invasive, aggressively growing into surrounding tissues, including underlying bone. While non-tonsillar OSCC generally has a lower tendency to spread to distant organs (metastasis to regional lymph nodes in less than 10% of cases, lungs in 3-36%), tonsillar OSCC is considerably more aggressive with a much higher likelihood of spreading.
Identifying Potential Signs
Recognizing the early signs of oral squamous cell carcinoma is important for dog owners. Dogs with OSCC often experience oral pain, leading to reluctance to eat or difficulty chewing. Owners might observe changes in eating habits, such as taking small bites or preferring softer foods.
Other common indicators include persistent bad breath, excessive drooling (sometimes with blood), and bleeding from the mouth. Swelling or visible lumps can develop in the mouth or jaw area, and teeth in the affected region might become loose. Any of these symptoms warrant prompt veterinary examination, as early detection significantly impacts treatment success.
Diagnostic Process and Treatment Options
Diagnosis of OSCC begins with a thorough oral examination, often under sedation or anesthesia, to assess the mouth and identify suspicious masses. A biopsy is then taken, where a small piece of tumor tissue is removed for microscopic analysis by a pathologist.
Imaging techniques determine tumor extent and potential spread. Dental X-rays reveal bone invasion, and advanced imaging like CT scans or MRIs provide detailed views for surgical planning. Blood work and urinalysis evaluate overall health. Lymph nodes in the neck may also be sampled via fine-needle aspiration to check for cancer spread.
Treatment for OSCC often involves a multi-modal approach. Surgical removal is generally preferred, especially if the tumor has not spread. This procedure may involve removing the tumor with surrounding healthy tissue, sometimes including part of the jawbone, to ensure all cancerous cells are excised. Dogs adjust well to partial jaw removal.
Radiation therapy is another common treatment option, used alone or in combination with surgery, especially if complete surgical removal is not feasible or if cancer cells remain after surgery. Radiation aims to damage cancer cells and can be used to slow tumor growth or as a palliative measure. While chemotherapy has shown limited effectiveness as a sole treatment for OSCC, it may be used alongside surgery or radiation for tumors with higher metastatic potential. Newer targeted therapies, such as Palladia, are also being explored for their ability to inhibit cancer growth.
Outlook and Ongoing Care
The outlook for dogs diagnosed with oral squamous cell carcinoma varies considerably, depending on factors like tumor size, location, cancer stage, and treatment effectiveness.
Tumors located in the rostral (front) part of the mouth generally have a more favorable prognosis compared to those on the tonsils or base of the tongue, which tend to be more aggressive and have a higher chance of metastasis.
Surgical removal, especially when the entire tumor is excised with clear margins, can be curative, leading to long-term survival. For instance, dogs undergoing surgical removal of mandibular tumors have reported median survival times ranging from 19 to 43 months, with high one-year survival rates. Following treatment, ongoing care is crucial, including regular veterinary check-ups to monitor for recurrence or new tumor development. Owners should also maintain good oral hygiene. In advanced cases where curative treatment is not possible, palliative care focuses on managing pain and maintaining the dog’s quality of life.