Oral tumors refer to an abnormal growth and unregulated replication of cells that takes place within your dog’s mouth, explained Jan Bellows, DVM, Dipl. AVDC, ABVP, and Christopher Pinard, DVM, of VCA Hospitals, an operator of over 1,000 animal hospitals in the US and Canada.
Your dog’s mouth is composed of various cell types such as epithelial (or skin) cells, bone cells, fibrous cells, and other cells that can become cancerous. Some tumors are benign, meaning they grow slowly and do not spread. However, malignant tumors can spread within your dog’s body.
Oral Cavity Tumors and Tumor-Like Lesions (2019)
Mateusz Mikiewicz and colleagues of journal portal Research Gate included a total of 486 oral cavity tumors and tumor-like lesions, consisting of 340 canines and 146 felines that were diagnosed routinely from 2015 to 2017. The lesions were classified as inflammatory, hyperplastic, or neoplastic (benign and malignant).
In canines, hyperplastic lesions accounted for 24.12% of the total oral lesions, most of which were gingival hyperplasia (96.34% of all hyperplastic lesions), with isolated cases of calcinosis circumscripta (2.44%) and giant cell granuloma (1.22%). Inflammatory lesions without distinct gingival hyperplasia represented 14.7% of the total oral lesions and included lymphoplasmacytic (62% of all inflammatory lesions), ulcerative (16%), purulent (8%), eosinophilic (6%), pyogranulomatous (4%), and mixed stomatitis (4%).
Benign neoplastic lesions accounted for 29.11% of the total oral lesions. This included peripheral odontogenic fibroma (65.66% of all benign tumors)—which is the second most common lesion in dogs—viral filiform papilloma (11.11%), acanthomatous ameloblastoma (8.08%), plasmacytoma (7.07%), single cases of granular cell tumor (3.03%), ossifying ﬁbroma (2.02%; 2/99), squamous papilloma (1.01%), Schwannoma (1.01%), and amyloid-producing odontogenic tumor (1.01%).
Malignant tumors comprised 32.06% of the total oral lesions in dogs. The most frequent one was melanoma (35.78% of all malignant tumors). Other common malignancies included squamous cell carcinoma (26.61%), ﬁbrosarcoma (12.84%) and osteosarcoma (10.09%). Less frequent malignancies were mast cell tumor (5.5%), lymphoma (3.67%), including non-epitheliotropic (75%) and epitheliotropic (25%) lymphoma, undifferentiated sarcoma (2.75%), haemangiosarcoma (1.83%), and myxosarcoma (0.92%).
Soft Tissue Affections of the Oral Cavity In Dogs
Inas N. El Husseiny, Haithem A. Farghali, and Aya N. Mohamed of scientific journal the American Journal of Research Communication wrote that a total of 639 cases of admitted dogs were assessed for the different oral cavity affections. From all examined cases, 21.1% were free of oral cavity affections while 78.8% were affected.
Among cases that show diseases of oral soft tissue, oro-nasal fistula was observed in 10.7% of dogs, along with stomatitis (14.2%), wound of the oral cavity (17.8%), ulcers of the oral cavity (14.2%), foreign bodies in oral cavity (10.7%), epulis (7.1%), oral neoplasia (17.8%), and salivary mucoceles (7.1%).
The researchers warned that toys and other products such as large treats cause tongue and oral injuries. Pet oral lesions are not life-threatening, other than malignant tumors or electric injuries. In fact, many oral lesions heal without treatment, but surgery is needed to hasten the healing process or to eliminate masses or foreign bodies. Large cutting wounds must be sutured to enable the normal continuity of the tissue.
What Causes Tumors?
The reason why your dog develops the aforementioned types of tumors is not straightforward. Most tumors are caused by a mix of risk factors, which can be hereditary or environmental, but very few have a “single known cause.” Males are twice as likely to develop oral cancer than females. Some breeds are also susceptible to oral cancers such as Boxer Dogs, Chow Chows, German Shepherds, Miniature Poodles, and more.
What Are the Signs of Oral Tumors?
Tumors come in many forms so the signs will depend on their location, type, size, and presence of spread. Melanomas are either pigmented or non-pigmented and may appear to be cauliflower-like. These may appear as swellings on your dog’s gums around its teeth or on the hard or soft palates. They often ulcerate or break open and bleed and may also become infected.
These tumors may look small but they can go deeper into the tissues to invade the underlying bone. If that happens, your dog will experience oral pain. Symptoms include bad breath, lack of appetite, drooling, difficulty eating, facial swelling, loss of teeth, and swelling of the lymph nodes.
How Are Oral Tumors Detected and Diagnosed?
Oral tumors can be detected during regular dental cleanings or while your dog undergoes anesthesia for an unrelated reason, said Joanne Intile, DVM, Diplomate ACVIM (oncology), of Vet Specialists.com, a joint venture of the American College of Veterinary Internal Medicine and the American College of Veterinary Surgeons. These procedures enable a thorough evaluation of your dog’s oral cavity, as well as the visualization of the abnormality while it is anesthetized.
Fine needle aspiration (FNA) may be done in case your dog has oral tumors, in which a small needle with a syringe suctions a sample of cells from the tumor. The samples are then placed on a microscopic side, which will be examined by a veterinary pathologist. FNA results may not be clear in some cases. Hence, a biopsy may be needed. A biopsy refers to the “surgical excision of a piece of the tumor.” The pieces are examined by a veterinary pathologist using a microscope.
How Are Oral Tumors Treated?
Surgery is the most common treatment method to treat oral tumors. CT scans are performed on the head/neck before your dog undergoes surgery. This is done to determine the extent of disease and it also aids in surgery panning. If the local lymph nodes are affected, then they may be removed along with the tumor.
As a preventive measure, your vet may recommend having these lymph nodes removed to ensure that the tumor will not spread. If the tumor has invaded the bone, removing a portion of your pet canine’s upper or lower jaw may be necessary. The tissues are examined by a pathologist after surgery to predict the probability of local recurrence or metastasis. If the whole tumor is submitted, the pathologist can assess whether the tumor was completely removed or if additional therapies are needed.
A second surgery or follow up treatments with radiation therapy may be required if a malignant tumor is not completely removed. The latter can be an alternative if surgery is not possible or warranted. Certain tumors like ameloblastomas respond to radiation therapy; however, surgery is still the most preferred option method if possible. If your vet observes metastasis, they may recommend your dog to undertake chemotherapy.
Signs of oral tumors depend on their location, size, and spread. Surgery is the primary treatment method to remove oral tumors, but chemotherapy or radiation therapy are other alternatives if surgery is not possible. Early intervention and treatment are recommended to ensure your dog’s health.