DENTISTRY
Squamous cell carcinoma is the most common oral tumor
in cats and carries a grave prognosis if located caudally
or if it affects the base of the tongue. If located rostrally,
surgery is the treatment of choice when clean, wide (at
least 2-cm) margins can be obtained (Figure 3).
As with squamous cell carcinoma, aggressive surgical
excision that includes part of the dog's or cat’s mandible or
maxilla is necessary. Radiation has been recommended to
treat microscopic disease in fibrosarcoma tumors that are
too large to obtain adequate margins. Hi-lo fibrosarcomas
carry a poor prognosis regardless of surgery or radiation
therapy. This may be partly due to the fact that most are
associated with the maxilla and are thus more difficult to
completely excise.
Osteosarcoma. Although malignant, oral osteosarcoma,
which usually occurs in the mandible of dogs, may not
be as aggressive as osteosarcoma of the appendicular
skeleton in the dog (Figure 5).
Figure 3. Squamous cell carcinoma in a cat's rostral mandible.
The NSAID meloxicam may have several beneficial effects
in treating feline squamous cell carcinoma, including pain
relief and reduced inflammation-associated neoplasia and
oedema. In the United States, meloxicam is licensed only
as a one-time injection for perioperative pain in cats. In
Australia and Europe, low doses (0.01-0.03 mg/kg a day)
have been used to treat osteoarthritis in cats without
significant side effects.
Fibrosarcoma. Diagnosed most commonly in the maxillae
of large-breed dogs, fibrosarcoma is locally invasive but
infrequently metastasises to the lungs (Figure 4). It is the
second most common oral malignancy in cats (after
squamous cell carcinoma). A subset of fibrosarcomas has
been recognized in which the tumors appear histologically
low-grade yet behave as high-grade malignancies
biologically (hi-lo).
Figure 5. Osteosarcoma affecting a dog's rostral mandible.
Osteosarcoma is rare in cats In a study of 51 dogs with
osteosarcoma treated with partial mandibulectomy alone
(32 dogs); partial mandibulectomy and chemotherapy
(10 dogs); partial mandibulectomy and radiation therapy
(3 dogs); partial mandibulectomy, radiation therapy, and
chemotherapy (4 dogs); and radiation therapy alone (2
dogs), the group treated with surgery alone achieved
a 1-year survival rate of 71%, compared with the entire
group’s 1-year survival rate of 60%. 5
In cases of maxillary osteosarcoma in both dogs and cats,
recurrence is common after surgery. Chemotherapy and
radiation in the treatment of oral osteosarcoma have not
been associated with an increase in survival.
Palliative radiation, single exposure every 2-3
months, very effective in controlling pain caused by
inoperable maxillary osteosarcomas
- Editor
For a quick reference of all the oral tumors that can
affect dogs and cats, see the sidebar, "Oral malignancy
nomenclature," on page 27..
Figure 4. Fibrosarcoma affecting a dog's maxilla
Issue 04 | AUGUST 2017 | 29