October 2025
In this VETgirl online veterinary continuing education blog, Dr. Michael Balke, DAVDC, F-OMFS kicks off a 2-part series on oral tumors in dogs and cats. Oral masses are a common finding in small animal practice, but they’re anything but straightforward. Their appearance, behavior, and prognosis vary widely depending on type and location, and early intervention matters. In Part 1, Dr. Balke walks us through how to approach oral tumors in dogs and cats, from clinical history and physical exam tips to biopsy technique and imaging recommendations, so you can feel confident in your diagnostic plan and set you and your patient up for success. Check out Part 2 on treatment options for oral tumors!

Oral Tumors in Dogs and Cats (Part 1 of 2) – What To Do?

by Dr. Michael Balke, DAVDC, F-OMFS

An oral tumor can involve the gingiva, lip, oral mucosa, tongue, bone, or a combination of any of these tissues.  They are a relatively common finding in small animal practice.  Their presentation, biological behavior and therapeutic outcomes vary widely depending on tumor type and location.  Early recognition, accurate diagnosis, and a multidisciplinary treatment approach are essential for optimal outcomes.  This first article in a two-article series will help the primary care veterinarian focus on how to systematically approach and diagnose oral tumors in canine and feline patients.

History

The initial step in working up an oral tumor is obtaining a good history and performing a complete physical examination.  The following questions can give the veterinarian insight into the biological behavior of the tumor (additional questions may be warranted based on answers):

  • When was the tumor first noted?
  • Is it changing in size/color?
  • Have you noticed drooling? Is there blood in it?
  • Has the client noticed any changes in their pet’s behavior (eating, drinking, upper respiratory sounds, playing with toys, pawing at mouth, being head shy)?

Malignant tumors tend to appear suddenly, get big quickly and can cause clinical signs such as difficulty eating and drinking, drooling with possible blood and the pet being sensitive around its mouth.  Benign tumors tend to stay the same size or gradually increase in size over time and cause minimal clinical signs.  These are not hard-set rules but merely guidelines as benign and malignant tumors can sometimes share similar features.

Physical Examination

 

Perform a thorough general and oral examination, sedation is often required to get good oral visualization and tumor evaluation.  Closely examine all the oral structures as other significant pathology could be present such as a large tonsil.   Referral to a board-certified veterinary dentist/oral surgeon and oncologist is recommended for many oral tumors so be as descriptive as possible about the size, location and appearance of the tumor in the medical record.  Use a metric ruler or calipers to get measurements of the tumor (length, width, height), if that is not possible use your best guess or reference something similar in size, example: peanut, grape, lime.  If teeth are involved list which teeth and if they are displaced, mobile, discolored.  Describe the color and surface texture (smooth, lobulated, ulcerated).  The best way to document the tumor is with high-quality pictures.   Ideally, pictures should be attached to the medical record and taken with good lighting, the mass and surrounding anatomy fully visible at different angles and with a ruler to reference size (see Figure 1).  Be alert for facial asymmetry, exophthalmos, nasal discharge or regional lymphadenopathy, which may indicate a deeper or more invasive disease.

Figure 1. Providing pictures of oral tumors at different angels with a ruler is a great way to document the size and appearance of the tumor in the medical record. Photos courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Diagnostics

Based on the history and exam findings, a differential diagnosis list can be formulated, but to determine what the tumor is, a biopsy must be performed.  Once you have a minimum diagnostic database (CBC, Chem, UA) biopsy is your next step.  It is best to avoid needle aspirates of oral tumors as they may not exfoliate well into the needle, resulting in minimal cells available for the pathologist to evaluate, making diagnosis difficult to impossible.  Obtaining a good quality biopsy is very important as the diagnosis, prognosis and treatment options are dependent on its results.  Biopsy collection must be performed under sedation or anesthesia with regional nerve blocks for the safety and comfort of the patient and veterinarian.  Prior to obtaining a biopsy, dental radiographs, or, if available, computed tomography, should be performed to assess the tissues involved with the tumor.  If bone is involved with the tumor, then including abnormal bone, in addition to soft tissue,  with the biopsy is important for a representative sample (see Figure 2).

Figure 2. This case helps show the importance of taking dental radiographs to assess bone involvement with the tumor.  An incisional biopsy was performed by removing portions of gingiva, alveolar bone and teeth involved with the tumor, and the site was closed with absorbable suture.  Photos courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Ideally, an incisional biopsy should be performed in which a representative section of the tumor is sampled.  The biopsy should be taken within the tumor itself and not through skin or healthy tissue as this may “seed” cancer cells outside the tumor.  Be sure to try and get to a biopsy from the surface to the core of the tumor as superficial samples may only diagnose inflammatory tissue that is surrounding the tumor.  Punch biopsies are very useful for non-bony tumors; crosscut fissure burs, such as the 701L, work well to cut samples from tumors involving bone.  When submitting a biopsy, give detailed information about the history, appearance and provide pictures along with dental imaging.  This information is valuable to the pathologist in addition to a good biopsy sample.  Excisional biopsies are the attempted complete removal of the tumor prior to a diagnosis and should only be considered for smaller, soft tissue tumors.  Taking a clear post-biopsy picture of the tumor site and surrounding anatomy is recommended, especially with excisional biopsies, as margins may not be clean and planning future surgical revision can be difficult if there is no macroscopic evidence of the tumor (Figure 3).

Figure 3. Taking pictures after obtaining a biopsy can be critical in planning future surgical margins as the biopsy site can be indistinguishable from surrounding tissue after it heals. The sutures marking the previous biopsy site in this picture helped determine surgical margins for a lip melanoma, as the case was referred after the site had healed. Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Screening for metastasis in tumors that are likely to be malignant is recommended.  Thoracic radiographs (3-view) or thoracic computed tomography and fine needle aspirate or biopsy of regional lymph nodes can be performed at the time of biopsy or after diagnosis.

Follow Up

Once a diagnosis has been made and, if performed, staging completed, an open conversation can be had with the client to discuss treatment options and prognosis specific to the type and stage of oral tumor affecting their pet.   It is imperative when talking to the client about how to move forward to listen, show empathy, acknowledge their concerns and ask questions to understand their goals.  Smaller benign tumors may be amendable to removal with the primary care veterinarian if they are comfortable with the procedure.  Consultation or referral to a board-certified veterinary dentist/oral surgeon and oncologist is recommended for patients with most oral tumors in order to provide the most progressive care.  If referral is not an option due to geographic or financial restrictions, primary care veterinarians may have access to specialists via email or virtual options to discuss the best course of action.  For clients that elect not to pursue treatment for their pet, monitoring quality of life and supportive care should be the goal.

In Part 2 of this series, we will discuss common oral tumors in dogs and cats along with appropriate treatment options and their associated prognoses.

Only VETgirl members can leave comments. Sign In or Join VETgirl now!