December 15, 2017

AVMA 2017: Managing Oral Tumors in Dogs

Early recognition and diagnosis, appropriate staging, and timely treatment elicit the best prognosis for these patients.
By Nicola M. Parry, BVSc, MRCVS, MSc, DACVP, ELS
Inflammatory or Reactive Lesions
Common inflammatory or reactive lesions that may arise in the canine oral cavity include gingival hyperplasia, focal fibrous hyperplasia, pyogenic granuloma, peripheral giant cell granuloma, and reactive exostosis, Dr. Vicari said.

She advised clinicians not to be misled by the term “epulis.” Although it has traditionally been used to describe non-neoplastic gingival enlargements, it refers to any gingival growth. It has no specific histopathologic features or biological behavior, so it could be used to describe any gingival tumor, benign or malignant, she said.

Tumor Evaluation
Before proceeding with anesthesia and surgery, clinicians should perform bloodwork on any dog presenting with an oral mass, Dr. Vicari said. They should conduct a thorough oral examination, including of the sublingual tissues. They should photograph oral masses, record their measurements (using the imprinted ruler on scalpel handles and periodontal probes for example), and perform complete intra-oral dental radiography. According to Dr. Vicari, recognizing some of the common radiographic features associated with odontogenic versus nonodontogenic tumors (Table) can help clinicians diagnose these lesions.



Advanced imaging techniques may also be useful, she noted. For example, computed tomography provides more detailed information about lesions and can be especially helpful when dealing with masses involving the maxilla, as well as with those located more caudally in the oral cavity.

A representative biopsy sample is also critical to diagnose any oral mass, she said. She advised clinicians to take samples from within the margins of a mass to avoid seeding tumor cells into normal tissue and inadvertently expanding the tumor margins. It is also important to avoid crossing tissue planes, she said. She advised clinicians to take deep samples from the mass to avoid hyperplastic tissue and avoid sampling any necrotic tissue. “Know your pathologist,” she added, stressing the importance of finding a reliable pathologist with experience evaluating oral tumors. Dr. Vicari emphasized the importance of correlating histopathologic features of a mass with clinical and radiographic findings.

Dr. Vicari discussed the value of taking fine-needle aspirate samples of regional lymph nodes for cytologic evaluation for tumor staging. However, she reminded clinicians that although the mandibular lymph nodes are the most accessible, only about half of oral tumors with metastasis involve them.1 Imaging examinations of the chest and abdomen are also useful in staging oral tumors, she said.

Conclusion
Dr. Vicari noted that surgical resection with 1- to 2-cm margins is the goal for most oral tumors but stated that if this is not feasible, surgical debulking may improve quality of life. Consulting an oncologist is also beneficial, she said, and adjunctive treatments may include radiation therapy, chemotherapy, and/or immunotherapy. “Treat early or refer,” she concluded. “Lots of good treatment options are available for oral tumors in dogs.”

 
Reference:
  1. Herring ES, Smith MM, Robertson JL. Lymph node staging of oral and maxillofacial neoplasms in 31 dogs and cats. J Vet Dent. 2002;19(3):122-126. doi: 10.1177/08987564020190030


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