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Oral Melanocytic Tumors in Dogs

Melanocytic tumors of the oral cavity arise from a local invasion of neoplastic melanocytic cells, or melanin-producing cells found in multiple sites throughout the body, including the mouth and skin. These tumors arise from the gingival surface and are aggressive in nature. They are usually raised, irregular, ulcerated, have a dead surface, and are highly invasive to bone.

Melanocytic tumors are the most common oral malignant tumors in dogs, commonly affecting dogs over 10 years of age. Such tumors may cause death as these render animals unable to eat, lose weight, and metastasis to other body parts.

Symptoms and Types

• Loose teeth
• Bad breath (halitosis)
• Excessive salivation (ptyalism)
• Difficulty swallowing (dysphagia)
• Oral discharge containing blood
• Weight loss (cachexia)

Causes

The underlying cause for oral melanocytic tumors is currently unknown.

Diagnosis

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform various laboratory tests, including a biochemistry profile, urinalysis, and complete blood count -- the results of which are typically normal -- as well as a physical examination, especially of the oral cavity.

Your veterinarian will also take a small deep tissue sample from the mass in the oral cavity, including a part of bone to be sent to a veterinary pathologist for further evaluation. Such biopsy samples are usually helpful in making a definitive diagnosis. In addition, X-rays of the oral cavity, skull, and lungs will help in the evaluation of the extent and location of metastasis.