Partial Maxillectomy and Premaxillectomy in the Treatment of Oral Neoplasia in the Dog and Cat

Surgical treatment of feline inductive odontogenic tumor by marginal resection in a cat

A 1-year-old mixed-breed cat was referred for an approximately 2-cm mass centered on the upper right canine tooth. Computed tomography (CT) revealed the lesion extended to the nasal cavity and orbit, causing thinning and expansion of the adjacent cortical bone. Excisional biopsy confirmed the diagnosis of a feline inductive odontogenic tumor. Based on the findings of CT imaging, the primary alveolar bone lesion was removed with the tumor, while the adjacent bones, which had been expanded and thinned, were preserved by marginal resection including the surrounding periosteum-like membrane. No local recurrence was observed for seven years. To validate the therapeutic outcome of this case, further research in diagnostic imaging and pathology will be crucial.

A modified full-thickness labial/buccal rotational flap reconstruction technique following bilateral rostral maxillectomy and nasal planectomy for resection of maxillary tumors: Technique and results in two dogs

OBJECTIVE

To describe a naso-facial reconstruction technique following bilateral rostral maxillectomy and its functional and cosmetic outcomes.

ANIMALS

Two dogs.

STUDY DESIGN

Clinical case series.

METHODS

Two dogs were presented with a right rostral maxillary mass. Preoperative biopsy and staging revealed a biologically high-grade and histologically low-grade fibrosarcoma (Hi-Lo FSA). A combined nasal planectomy and radical bilateral rostral maxillectomy was performed sparing the labial/buccal mucocutaneous flaps bilaterally. Surgery resulted in asymmetry of the width of the flaps; the narrower flap was rotated medially to reconstruct the lip and create an oral vestibule. The wider flap was rotated medially to cover the remaining dorsolateral opening of the nasal conchae. The flaps overlapped in a parallel manner, discretely concealing the nasal passages, and separating them from the oral cavity. Hemorrhage occurred in both dogs, with one dog requiring a blood transfusion postoperatively.

RESULTS

Oral Hi-Lo FSA with tumor-free margins was confirmed in both dogs. Both dogs recovered uneventfully within 4 weeks. Owners reported being very satisfied with the functional (return to normal exercise/activities and uncompromised respiration) and cosmetic outcomes. Based on the owners' telephone follow up, no tumor recurrence was noted at 15 (Dog 1) and 6 (Dog 2) months postoperatively.

CONCLUSION

The full-thickness bilateral labial/buccal rotational flaps were used successfully to reconstruct the rostral maxilla, external nose and facial defects involving the nasal cavity. The technique resulted in acceptable functional and cosmetic outcomes and can be considered for naso-facial reconstruction in selected cases.

Performances of novel custom 3D-printed cutting guide in canine caudal maxillectomy: a cadaveric study

Introduction

Caudal maxillectomies are challenging procedures for most veterinary surgeons. Custom guides may allow the procedure to become more accessible.

Methods

A cadaveric study was performed to evaluate the accuracy and efficiency of stereolithography guided (3D-printed) caudal maxillectomy. Mean absolute linear deviation from planned to performed cuts and mean procedure duration were compared pairwise between three study groups, with 10 canine cadaver head sides per group: 3D-printed guided caudal maxillectomy performed by an experienced surgeon (ESG) and a novice surgery resident (NSG), and freehand procedure performed by an experienced surgeon (ESF).

Results

Accuracy was systematically higher for ESG versus ESF, and statistically significant for 4 of 5 osteotomies (p < 0.05). There was no statistical difference in accuracy between ESG and NSG. The highest absolute mean linear deviation for ESG was <2 mm and >5 mm for ESF. Procedure duration was statistically significantly longer for ESG than ESF (p < 0.001), and for NSG than ESG (p < 0.001).

Discussion

Surgical accuracy of canine caudal maxillectomy was improved with the use of our novel custom cutting guide, despite a longer duration procedure. Improved accuracy obtained with the use of the custom cutting guide could prove beneficial in achieving complete oncologic margins. The time increase might be acceptable if hemorrhage can be adequately controlled in vivo. Further development in custom guides may improve the overall efficacy of the procedure.

Sternohyoideus-sternothyroideus muscle flap to reconstruct oronasal fistulas due to maxillary cancer in four dogs

OBJECTIVE

To describe the repair of oronasal fistulas in dogs treated for maxillary cancer, with a novel sternohyoideus-sternothyroideus muscle flap, and to report the outcome.

ANIMALS

Client-owned dogs (n = 4) with oronasal fistulas related to cancer.

STUDY DESIGN

Short case series.

METHODS

Maxillary defects were caused by tissue destruction by the tumor and tumor response to radiation therapy in two cases and a complication of caudal maxillectomy in two cases, one of which had neoadjuvant radiation therapy. All tumors were >4 cm at the level of the maxilla. Flaps were harvested by transecting the ipsilateral sternothyroideus and sternohyoideus muscles from their origin at the manubrium and costal cartilage. The muscles were rotated around the base of the cranial thyroid artery and tunneled subcutaneously in the neck and through an incision in the caudodorsal aspect of the oral cavity. The muscle flap was sutured to the edges of the oronasal fistula.

RESULTS

The flap reached as far rostral as the level of the first premolar without tension. All dogs had clinical signs that improved postoperatively. All dogs had partial dehiscence of the flap.

CONCLUSION

This flap was associated with a high rate of complications; however, all flaps were used in challenging cases. Clinical signs related to oronasal fistula were improved in all dogs in this case series.

Impact of the Surgical Environment on the Incidence, Timing, and Severity of Complications Associated With Oromaxillofacial Oncologic Surgery in Dogs

Numerous reports describe complication rates associated with oromaxillofacial oncologic surgery in dogs, however, investigation regarding the impact of the surgical environment on the incidence of complications is under reported. The objective of this retrospective cohort study, including 226 dogs surgically treated for oromaxillofacial tumors between January 1, 1997 and December 31, 2018, is to evaluate the impact of the surgical environment on the incidence of complications in oromaxillofacial oncologic surgery in dogs. A secondary objective is to report the incidence of local complications in oromaxillofacial oncologic surgery and characterize the type, timing, and severity of complications encountered. Incidence of complications was identified to be 69.9%. No significant association was identified between the incidence, timing, or severity of complications and the training background of the clinician, physical location of the procedure, or the ostectomy instrument used. These results suggest that the surgical environment has little impact on the incidence, timing, and severity of complications in dogs undergoing oromaxillofacial oncologic surgery. The results also emphasize the importance of preparing the surgical team and the client for a high incidence of complications associated with oromaxillofacial oncologic surgery in dogs and indicate that both short-term and long-term follow up is important in these cases. Oromaxillofacial surgery performed by residents-in-training within a veterinary teaching environment with adequate supervision appears to be safe.

Incidence and Risk Factors for Surgical Site Infections Following Oromaxillofacial Oncologic Surgery in Dogs

Antibiotic stewardship in veterinary medicine is essential to help prevent resistant bacterial infections. Critical evaluation into the benefits of prophylactic use of antibiotics during veterinary surgical procedures is under reported and additional investigation is warranted. The objectives of this paper were to determine the incidence of surgical site infection in dogs that underwent oromaxillofacial oncologic surgery and to identify risk factors for the development of surgical site infection. In this retrospective cohort study including 226 dogs surgically treated for oromaxillofacial tumors between January 1, 1997 and December 31, 2018, the incidence of surgical site infection was determined to be 7.5%. Univariable logistical regression models were used to evaluate potential risk factors for development of surgical site infections including signalment, tumor type, antibiotic protocol, time under anesthesia, location of surgical procedure (dental suite vs. sterile operating room), specific comorbidities, and surgical margins obtained. Anesthetic events lasting greater than 6 h were significantly associated with development of infection. Signalment, comorbidities, administration of anti-inflammatory and immunosuppressive medications, tumor type, histological margin evaluation, surgical procedure location, and antibiotic protocols were not significant contributors to development of infection. Use of antibiotic therapy in this cohort was not protective against development of infection and may not be routinely indicated for all oromaxillofacial oncologic surgeries despite common promotion of its use and the contaminated nature of the oral cavity. Anesthetic time significantly contributed towards the development of infection and use of perioperative antibiotics for surgical procedures lasting >6 h may be routinely warranted.

Staged mandibular lip flap for closure of a large palatal defect after maxillectomy in a dog

OBJECTIVE

To report closure of an oronasal defect secondary to maxillectomy with a staged mandibular lip flap.

STUDY DESIGN

Case report ANIMALS: One 9-year-old female spayed golden retriever.

METHODS

A combined dorsolateral and intraoral approach was used to perform a central maxillectomy to excise a 2.4- × 2- × 2.7-cm oral osteosarcoma with 1-cm margins. A buccal mucosal flap was used to close the palatal defect but the site subsequently dehisced. A staged mandibular lip flap was performed to close the defect. An incision was made on the mandible at the intersection of the buccal mucosa and gingiva from the mandibular canine to the level of the commissure. A second incision was made 3 cm ventral to the lip margin. The flap pedicle was based at the commissure. The flap was rotated to cover the palatal defect from rostral to the canine tooth to the fourth premolar. A second procedure was performed 4 weeks after flap placement to desquamate the haired skin and transect the flap pedicle.

RESULTS

Partial dehiscence at the caudal aspect of the flap occurred after the first revision. The defect was closed after pedicle transection on day 41, with acceptable cosmesis. The dog was eating canned food with no evidence of discomfort 159 days after the maxillectomy. Recurrence was noted on day 270 postoperatively.

CONCLUSION

Closure of a large palatal defect with a staged mandibular lip flap led to good cosmesis and function.

Ligation of the Maxillary Artery Prior to Caudal Maxillectomy in the Dog-A Description of the Technique, Retrospective Evaluation of Blood Loss, and Cadaveric Evaluation of Maxillary Artery Anatomy

Two different surgical techniques have been described for performing caudal maxillectomies in dogs including the intraoral (IO) and combined dorsolateral and intraoral (DL-IO) approach. Hemorrhage is the most common intraoperative complication reported during these procedures as maxillary arterial ligation is not performed until after all osteotomies and mobilization of tumor-bearing bone. The objectives of this study were to describe a modified approach for caudal maxillectomy in the dog involving preligation of the maxillary artery, to retrospectively evaluate the ability of this modified approach to limit hemorrhage in a cohort of 22 dogs, and to clarify the vascular anatomy of the maxillary artery and its branches in relation to associated nerves. Medical records were retrospectively reviewed for cases that had caudal maxillectomy via a combined approach (with or without preligation of the maxillary artery) from January 1, 2004 to December 31, 2019. Twenty-two cases were identified, six without, and 16 with arterial preligation, respectively. Osteotomies were completed with a high-speed handpiece and rotary bur (n = 18), or oscillating bone saw (n = 4). All six (100%) dogs in the traditional DL-IO group developed hypotension under general anesthesia. Four (67%) of these required intraoperative blood transfusions, one of which required an additional postoperative blood transfusion. In contrast, only one of 16 (6%) dogs in the modified DL-IO group required an intraoperative blood transfusion, and only three (19%) developed hypotension. Moreover, a significant association was detected between postoperative PCV and the two different surgical approaches (P = 0.021). These results demonstrate the effectiveness of preligation of the maxillary artery in preventing hemorrhage in caudal maxillectomies in dogs and this represents an improvement in outcome over previously reported studies. Decreased intraoperative hemorrhage may improve surgical exposure and decrease overall patient morbidity.

World Small Animal Veterinary Association Global Dental Guidelines

Dental, oral, and maxillofacial diseases are some of the most common problems in small animal veterinary practice. These conditions create significant pain as well as localized and potentially systemic infection. As such, the World Small Animal Veterinary Association (WSAVA) believes that un- and under treated oral and dental diseases pose a significant animal welfare concern. Dentistry is an area of veterinary medicine which is still widely ignored and is subject to many myths and misconceptions. Effective teaching of veterinary dentistry in the veterinary school is the key to progression in this field of veterinary medicine, and to the improvement of welfare for all our patients globally. These guidelines were developed to provide veterinarians with the information required to understand best practices for dental therapy and create realistic minimum standards of care. Using the three-tiered continuing education system of WSAVA, the guidelines make global equipment and therapeutic recommendations and highlight the anaesthetic and welfare requirements for small animal patients. This document contains information on common oral and dental pathologies, diagnostic procedures (an easily implementable and repeatable scoring system for dental health, dental radiography and radiology) and treatments (periodontal therapy, extractions). Further, there are sections on anaesthesia and pain management for dental procedures, home dental care, nutritional information, and recommendations on the role of the universities in improving veterinary dentistry. A discussion of the deleterious effects of anaesthesia free dentistry (AFD) is included, as this procedure is ineffective at best and damaging at worst. Throughout the document the negative effects of undiagnosed and/or treated dental disease on the health and well-being of our patients, and how this equates to an animal welfare issue, is discussed.

Outcomes of cats treated with maxillectomy: 60 cases. A Veterinary Society of Surgical Oncology retrospective study

Maxillectomy is poorly described for the management of oral tumours in cats and is occasionally not recommended because of the high complication rate and sub-optimal outcome reported in cats treated with mandibulectomy. The purpose of this study was to retrospectively evaluate the complications and oncologic outcome in cats treated with maxillectomy. Sixty cats were included in the study. Maxillectomy procedures included unilateral rostral (20.0%), bilateral rostral (23.3%), segmental (10.0%), caudal (20.0%) and total unilateral maxillectomy (26.7%). Intra-operative and post-operative complications were reported in 10 (16.7%) and 34 (56.7%) cats, respectively. The most common post-operative complications were hyporexia (20.0%) and incisional dehiscence (20.0%). The median duration of hyporexia was 7 days. Benign tumours were diagnosed in 19 cats (31.7%) and malignant tumours in 41 cats (68.3%). Local recurrence and metastatic rates were 18.3% and 4.9%, respectively; the median progression-free interval (PFI) was not reached. The disease-related median survival time was not reached overall or for either benign or malignant tumours. The 1- and 2-year survival rates were, respectively, 100% and 79% for cats with benign tumours, 89% and 89% for cats with malignant tumours, 94% and 94% for cats with fibrosarcomas, 83% and 83% for cats with squamous cell carcinomas, and 80% and 80% for cats with osteosarcomas. Poor prognostic factors included mitotic index for PFI, adjuvant chemotherapy for both PFI and survival time, and local recurrence for survival time. Maxillectomy is a viable treatment option for cats resulting in good local tumour control and long survival times.

Diagnostic Yield of Micro-Computed Tomography (micro-CT) Versus Histopathology of a Canine Oral Fibrosarcoma

Micro-computed tomography (micro-CT) imaging currently gains increased interest in human as well as veterinary medicine. The ability to image 3-dimensional (3D) biopsy specimens nondestructively down to 1 µm spatial resolution makes it a promising tool for microscopic tissue evaluation in addition to histopathology. Visualizing tumor margins and calculating tumor load on 3D reconstructions may also enhance oncological therapies. The objective of this study was to describe the workflow from tumor resection to histopathological diagnosis, using both routine hematoxylin-eosin (HE)-stained sections and micro-CT tomograms on a stage II oral fibrosarcoma in a 7-year-old Hovawart dog. The maxillectomy specimen was fixed with formalin and stained with an X-ray dense soft tissue contrast agent. Micro-CT imaging was done using an ex vivo specimen micro-CT device. Tumor margins could not be exactly determined on micro-CT tomograms due to limited image resolution and contrast. Histopathology was performed after washing out the contrast agent. It showed neoplastic cells infiltrating the surrounding tissue further than assumed from micro-CT images. A total tumor volume of 10.3 cm³ could be calculated based on correlating micro-CT tomograms with HE-stained sections. This correlative approach may be of particular interest for oncological therapy. More than that, micro-CT imaging technology supported histopathology by means of 3D orientation and selection of slices to be cut on determining tumor margins. In this clinical case report, micro-CT imaging did not provide unambiguous clinical evidence for oncological decision-making, but it showed potential to support histopathology and calculate tumor volume for further clinical use.

Outcome and prognostic factors following curative-intent surgery for oral tumours in dogs: 234 cases (2004 to 2014)

OBJECTIVES

To describe the long-term outcomes and prognostic factors associated with curative-intent surgery for oral tumours in a large series of dogs.

METHODS

Retrospective review of records for dogs with oral tumours treated with curative-intent surgery. Data collected included signalment, weight, surgical procedure, lymph node staging results, computed tomography results, tumour size, histopathology results including margin evaluation, complications, adjunctive therapies, local recurrence or metastasis, date and cause of death and owner satisfaction.

RESULTS

Median cause-specific survival was shortest for malignant melanoma (206 days) and osteosarcoma (209 days). Local recurrence rate was highest for fibrosarcoma (54·2%) and distant metastatic rate was highest for malignant melanoma (30%). Curative-intent surgery resulted in complete surgical margins in 85·2% of cases.

CLINICAL SIGNIFICANCE

Results suggest tumour type, completeness of excision, tumour size, and age may affect disease-free interval and cause-specific survival. Fibrosarcoma had a higher risk of recurrence compared to other tumour types.

Evaluation of an Accelerated Chemoradiotherapy Protocol for Oropharyngeal Squamous Cell Carcinoma in 5 Cats and 3 Dogs

Accelerated radiation therapy protocols address the specific biology of aggressive oropharyngeal squamous cell carcinoma and this approach was applied in 5 feline and 3 canine oropharyngeal squamous cell carcinoma patients where surgery was not possible (4/5 feline and 2/3 canine cases) or was declined (1/5 feline and 1/3 canine cases). A protocol using 14 fractions of 3.5 Gy over 9-days, combined with carboplatin chemotherapy as a radiosensitiser (total dose 180 mg/m2 in feline and 300 mg/m2 in canine cases) resulted in a complete tumor response in most cases (4/5 feline and 3/3 canine cases) with acceptable acute and long-term side effects. Results achieved in feline cases correspond with published data where these specific radiotherapy protocols were employed. A complete response and long-term survival (> 2-years) was achieved in all canine patients. Although no standardized chemoradiotherapy protocols currently exist, this therapeutic approach can be a useful addition for the management of oropharyngeal squamous cell carcinoma of cats and dogs when the goals of treatment include maximizing tumor control while maintaining function and quality of life.

[Prognosis of canine oral (gingival) squamous cell carcinoma after surgical therapy. A retrospective analysis in 40 patients]

OBJECTIVE

Retrospective analysis of dogs with gingival squamous cell carcinoma (SCC) surgically treated using jaw resection. Material and me- thods: A total of 40 dogs were enrolled in the study. Dogs with incomplete tumour resection or metastases were subjected to adjuvant chemotherapy using carboplatin. Breed, age, tumour localisation, postsurgical complications, survival times and prognostic factors were evaluated.

RESULTS

There were no breed predispositions. The median age was 9.5 years (mean 8.6 years; range 0.5-15.5 years). At the time of presentation, two dogs (5%) had lymph node metastases (N1). The median survival time (ST) of all the patients was 44.8 months. In 15 patients, the tumour was located in the maxilla, whereas 25 dogs had a mandibular tumour location. The median ST in dogs with maxillary tumours was 39 months (95% confidence interval [CI] 24 months), while patients with maxillary tumours survived a median of 43 months (95% CI 33-70 months). There was no significant difference in the ST in patients with maxillary versus man- dibular tumours (p = 0.985). On multivariate analysis, only the tumour stage was found to be significantly associated with survival (p = 0.0047). Patients with stage N0 survived a median of 44 months (95% CI 36-80 months). The two dogs with lymph node metastasis (N1) sur- vived 18 and 70 months following jaw resection and carboplatin chemotherapy, respectively. According to the histological findings, tumour resection was incomplete in five patients. These dogs received adjuvant carboplatin chemotherapy, resulting in an ST of between 6 and 146 months.

CONCLUSION AND CLINICAL RELEVANCE

Prognosis depends on the tumour stage, while for complete local excision of the affected jaw segment a good prognosis can be given and the majority of the patients can be cured. The supposedly more malignant behaviour of gingival SCCs located in the caudal aspects of the oral cavity could not be confirmed. Patients with metastasis of the local lymph nodes can achieve acceptable survival times. Jaw resections have low complication rates and a good functional outcome.

A naturally occurring feline model of head and neck squamous cell carcinoma

Despite advances in understanding cancer at the molecular level, timely and effective translation to clinical application of novel therapeutics in human cancer patients is lacking. Cancer drug failure is often a result of toxicity or inefficacy not predicted by preclinical models, emphasizing the need for alternative animal tumor models with improved biologic relevancy. Companion animals (dogs and cats) provide an opportunity to capitalize on an underutilized and biologically relevant translational research model which allows spontaneous disease modeling of human cancer. Head and neck squamous cell carcinoma (HNSCC) is a common cancer with a poor prognosis and limited clinical advancements in recent years. One potential novel spontaneous animal tumor model is feline oral squamous cell carcinoma (FOSCC). FOSCC and HNSCC share similar etiopathogenesis (tobacco and papillomavirus exposure) and molecular markers (EGFR, VEGF, and p53). Both human and feline SCCs share similar tumor biology, clinical outcome, treatment, and prognosis. Future clinical trials utilizing FOSCC as a tumor model may facilitate translation of preclinical cancer research for human cancer patients.

Oronasal fistula repair utilizing a temporalis muscle flap in a dog with severe trismus

A 9 yr old spayed female cocker spaniel presented for evaluation of an invasive maxillary squamous cell carcinoma. Curative intent surgery and radiation therapy allowed for local control of the neoplasm; however, the development of a persistent oronasal fistula prevented a complete recovery. A temporalis myofascial rotation flap allowed for successful resolution of the maxillary defect. Implementation of the flap was relatively simple and was associated with few complications.

Maxillary osteomyelitis in two Scottish terrier dogs with chronic ulcerative paradental stomatitis

Two Scottish terrier dogs were presented for recurrent oral problems. They were diagnosed with refractory chronic ulcerative paradental stomatitis and necrosis of the incisive and maxillary bones. Both dogs were treated with a combination of bilateral rostral maxillectomy and tooth extractions. The ostectomy was performed with a specific cutting device using piezoelectric bone surgery technology. These two cases show that a precise evaluation of dogs is essential for the diagnose of chronic ulcerative paradental stomatitis and its differentiation from mucocutaneous autoimmune diseases.

Radical maxillectomy as a successful treatment for gunshot-induced maxillary and nasal cavity trauma in a dog

OBJECTIVE

To report the successful treatment of gunshot-induced maxillary and nasal cavity damage with total maxillectomy in a two-year-old Labrador retriever dog.

METHODS

Radical maxillectomy was performed on highly comminuted maxillary and nasal cavity fractures resulting from gunshot trauma. The procedure was performed to remove the damaged region and reconstruct the remaining tissue.

RESULTS

Treatment of the fractures by total maxillectomy was successful in reconstruction of the remaining structures following debridement and in re-establishing return to normal activities and high owner satisfaction.

CLINICAL SIGNIFICANCE

The outcome in this case suggests that severe maxillary and nasal cavity trauma in other dogs may be treated with radical maxillectomy given appropriate patient and owner selection.

Zygomatic salivary mucocoele as a postoperative complication following caudal hemimaxillectomy in a dog

Zygomatic mucocoele is reported as a postoperative complication occurring secondary to a caudal hemimaxillectomy in a two-year-old Labrador retriever. The dog was presented with a history of a rapidly growing oral mass, identified as a soft tissue sarcoma. A caudal hemimaxillectomy via an intraoral approach was performed as treatment for local control of the oral mass. Fifteen days postoperatively, periorbital swelling and exophthalmos developed on the ipsilateral side. The degree of swelling progressed and was identified by computed tomography, ultrasound and cytology as a salivary mucocoele. Zygomatic sialoadenectomy was performed via a modified lateral approach with zygomatic osteotomy. A small amount of discharge persisted from the surgical site but gradually resolved. Recurrence of the periorbital swelling and exophthalmos was noted 25 days later and further surgery was performed to excise residual salivary tissue. Adjuvant radiotherapy was performed, however local recurrence of the oral mass was identified 5 months postoperatively and the patient subsequently euthanased. Salivary mucocoele has been cited as a possible postoperative complication following maxillectomy and mandibulectomy procedures; however to the authors' knowledge, only one previous case report exists in the literature. The current case documents a zygomatic salivary mucocoele occurring subsequent to caudal hemimaxillectomy.

Mandibulectomy and Maxillectomy

In an animal presented for evaluation of an oral tumor, the extent of the disease is based on the systematic evaluation of the tumor, including diagnostic imaging, and the assessment of regional lymph node involvement and distant metastases. The nature of the disease is determined by an incisional biopsy and histopathologic examination. The choice of treatment and expected outcome are based on the stage and expected biologic behavior, which is well known for many oral tumor types. The various mandibulectomy and maxillectomy techniques have been shown to give good functional and cosmetic results.

Bilateral Rostral Maxillectomy and Nasal Planectomy for Large Rostral Maxillofacial Neoplasms in Six Dogs and One Cat

This paper describes in detail an aggressive rostral maxillectomy procedure in one cat and six dogs, and the postoperative complications and outcomes are reported. The surgeries were performed to attempt complete excision of large and extensive rostral maxillary fibrosarcomas (n=4), squamous cell carcinomas (n=2), or poorly differentiated mesenchymal neoplasia (n=1). The surgeries involved transection of the maxilla at the level of premolar (PM)1 and PM2 in a cat and two dogs, and between PM2 and PM3 in four dogs. There were no intraoperative complications. Complete margins of resection were obtained in all cases. The postoperative appearance was acceptable to owners. Local recurrence was only observed in one dog (10 months after surgery) during a follow-up period of 11 to 66 months (median, 21.5 months).

Combined dorsolateral and intraoral approach for the resection of tumors of the maxilla in the dog

This paper describes in detail a combined dorsal and intraoral approach for maxillectomy for tumors involving tissues more caudal to the third premolar. The only intraoperative complication was that of blood loss, with six out of 20 dogs requiring a single unit of blood. Histopathologically clean margins were obtained in 14 of the 20 cases, with a recurrence rate of 50% in these dogs and a median time to recurrence of 24 months. This represents an improvement in outcome over previously reported studies, and the authors postulate this is due to the better exposure and access to the area afforded by the combined approach over the standard intraoral approach.

Multimodality therapy for head and neck cancer

The refinement of radiation therapy techniques should result in a decrease in morbidity in canine and feline nasal carcinoma patients and should further allow for the addition of adjuvant therapies. Patients with large oral tumors that are incompletely excised should have radiation therapy added to their treatment regimen. Tumors with significant metastatic potential, such as melanoma, should be considered for addition of chemotherapy. Carboplatin has activity in melanomas and is being added at several institutions, but trial results are not yet available. Chemoradiation has become the treatment of choice for human head and neck squamous cell carcinomas but remains largely unexplored in veterinary medicine. Hopefully, development of chemoradiation will benefit feline squamous cell carcinoma patients, because current treatment regimens are largely ineffective. Immunotherapy agents and targeted biologic therapeutics seem to hold promise for the future.

Use of mandibular symphysiotomy to allow extensive caudal hemimaxillectomy in a dog

A 5-year-old dog was presented with a large caudal maxillary osteosarcoma, which was causing extreme pain on opening of the mouth. The mass was not resectable through a standard oral approach. This article describes the successful use of mandibular symphysiotomy to allow extensive caudal hemimaxillectomy to remove the mass and provide excellent postoperative quality of life for the dog.

Evaluation of piroxicam for the treatment of oral squamous cell carcinoma in dogs

OBJECTIVE

To evaluate the use of piroxicam for the treatment of oral squamous cell carcinoma in dogs.

DESIGN

Prospective case series.

ANIMALS

17 dogs with measurable oral squamous cell carcinoma.

PROCEDURE

Dogs were treated with piroxicam at a dosage of 0.3 mg/kg (0.14 mg/lb) of body weight, PO, every 24 hours until progressive disease or unacceptable signs of toxicosis developed or the dog died.

RESULTS

One dog had a complete remission (maxillary tumor), and 2 dogs had partial remissions (lingual tumor and tonsillar tumor). An additional 5 dogs had stable disease, including 1 with a maxillary tumor, 2 with mandibular tumors, and 2 with tonsillar tumors. Variables associated with tumor response were not identified. Median and mean times to failure for the 3 dogs that had a remission were 180 and 223 days, respectively. Median and mean times to failure for the 5 dogs with stable disease were 102 and 223 days, respectively. Time to failure was positively associated with tumor response and negatively associated with tumor size. One dog had mild adverse gastrointestinal tract effects that resolved with the addition of misoprostol to the treatment regimen.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that piroxicam may be useful in the treatment of dogs with oral squamous cell carcinoma; response rate was similar to that reported for other cytotoxic treatments. Larger-scale studies are warranted to determine what role piroxicam may have, alone or in combination with other treatments, for the treatment of dogs with oral squamous cell carcinoma.

Radiation therapy for long-term control of odontogenic tumours and epulis in three cats

Orthovoltage radiation was used to treat odontogenic tumours in three cats following incomplete surgical resection. Cats received a total radiation dose of 48-52 Gy over a period of 26-29 days. Acute toxicities were mild, consisting of hair loss within the radiation field in all cats, and mild mucositis in one cat. All cats had long-term (>35 months) control of their tumour, and two cats are still alive without recurrence of tumour 60 and 39 months, respectively, after completing treatment. Radiation therapy should be considered to be an adjuvant to incomplete surgery in cats with odontogenic neoplasms or epulides.

Radiation oncology of head and neck tumors

Malignant tumors of the head and neck region occur commonly in veterinary medicine. Unfortunately, tumors in the head and neck can cause treatment dilemmas because many neoplastic entities at this site are locally aggressive. Additional local therapies such as radiation therapy are becoming commonplace as standardized therapies for many head and neck tumors in veterinary medicine.

Total and partial orbitectomy for the treatment of periorbital tumors in 24 dogs and 6 cats: a retrospective study

Total or partial orbitectomy were used to treat 24 dogs and six cats with invasive periorbital tumors. The surgical procedure and clinical results were evaluated in this retrospective study. The most common types of tumors treated in this series of patients were multilobular osteochondrosarcoma and squamous cell carcinoma. Two patients died of cardiopulmonary arrest within 24 hours after surgery. One patient developed neurological signs after total orbitectomy that resolved with conservative therapy. Minor complications, which included infection, strabismus, and conjunctivitis, occurred in seven patients. Regrowth of tumor in the periorbital region occurred in 11 patients (36.7%). Tumor resection by orbitectomy provided local disease-free interval of more than 1 year in more than 50% of patients. Survival rate for the first year was 70.4% in this series of patients as determined by life table analysis. Orbitectomy requires detailed knowledge of regional anatomy and experience with performing a combination of surgical procedures. Preoperative diagnostic tests should include imaging techniques to define the extent of the disease. When performed properly, orbitectomy is a valuable procedure that can be used to effectively treat invasive tumors of the orbit.

Maxillectomy and targeted radionuclide therapy with 153Sm-EDTMP in a recurrent canine osteosarcoma

An eight-year-old dog with a local relapse of an osteosarcoma was treated with partial maxillectomy and systemic radionuclide therapy that involved two injections, 43 and 45 megabecquerels per kg bodyweight of the bone-seeking agent samarium-153-ethylenediaminetetramethylene phosphonic acid (153Sm-EDTMP), 15 weeks apart. A transient drop in white blood cell count and platelet count was observed following each 153Sm-EDTMP treatment. Follow-up 21 months after surgery revealed no evidence of local recurrence or metastases. The dog was in excellent condition, suffering only minor sequelae from the surgical procedure. Compared with historical controls treated with surgery alone, the combination of surgery and systemic radionuclide therapy seems a promising strategy for the treatment of canine osteosarcoma.

Combined resection of the nasal planum and premaxilla in three dogs

Surgical techniques for removal of tumors that affect the nasal planum or the premaxilla have been described. For extensively invasive malignancies, these techniques may be inadequate if used alone to achieve wide surgical margins. An operative technique that combines resection of the nasal planum and premaxilla has been developed for extensive malignant tumors of the nasal planum or premaxilla. This technique was used in three dogs and resulted in an acceptable cosmetic appearance and good function and tumor control. Complications after surgery included minor bleeding and partial dehiscence of the suture lines in two dogs and stenosis of the nasal orifice in one dog.

Hemimaxillectomy for the treatment of oral tumors in 69 dogs

Hemimaxillectomy was performed in 69 dogs for the treatment of benign or malignant maxillary tumors. Eighteen dogs with ameloblastomas had a median disease-free interval of 21.5 months (range, 1 to 76 months), with a 72% 1-year survival time. There was recurrence in three dogs, with metastasis after malignant transformation in one of them. Based on calculated survival curves, seven dogs with squamous cell carcinoma had a median survival time of 19.2 months (range, 2 to 24 months), with a 57% 1-year survival time. There was local recurrence in two dogs. Twenty-three dogs with melanoma had a median survival time of 9.1 months (range, 1 to 46 months), and a 27% 1-year survival time. Twelve dogs died or were euthanatized because of recurrence or metastases. Fifteen dogs with fibrosarcoma had a median survival time of 12.2 months. Eight dogs died or were euthanatized because of recurrence or metastases. Six dogs with osteosarcoma had a median survival time of 4.6 months (range, 1 to 12.5 months), with a 17% 1-year survival time. Five dogs died or were euthanatized for recurrence or metastases. Tumor size or location and type of partial maxillectomy performed did not affect survival.

Aggressive surgery in the management of oral neoplasia

Aggressive surgical techniques such as mandibulectomy and maxillectomy have become the standard surgical treatment for oral neoplasia. The development of these procedures has provided some hope for a cure or at least extended life span in animals with oral tumors. Although large segments of bone and soft tissue are usually removed, function and cosmesis are acceptable. Postoperative complications are common but are usually treatable. Best prognosis for long-term survival is for patients with benign tumors or early SCC. Less favorable results have been found with fibrosarcoma and MM. Continued research in adjunctive treatment of these tumors may further improve the results of combined surgical and medical management.

Wide local excision of acanthomatous epulides in the dog

Twenty-five dogs bearing acanthomatous epulides of the oral cavity underwent tumor resection by wide local excision. The surgical procedures included rostral mandibulectomy, removal of the mandibular body, premaxillectomy, and partial maxillectomy. Postoperative complications were rare, and local recurrence was not encountered in any dogs over periods of 1 to 6 1/2 years (median, 22 months). The authors conclude from the high incidence of local recurrence after simple excision through the tumor margins and the potential for malignant transformation after irradiation that wide surgical resection is the technique of choice for the management of acanthomatous epulis.

Oral surgery. Radical resection of maxillary and mandibular lesions

The results obtained following both maxillectomy and mandibulectomy in animals with benign disease show that these procedures are practical. The challenge is to select those animals with malignant disease where the disease is sufficiently localized so that radical resection will be curative, or where residual disease can be controlled by adjuvant therapy. The series of cases reported in Tables 1 and 2 represent animals treated during the "developmental phase" of these procedures. With 5 years of case experience now available, the usefulness and limitations of these procedures are becoming clearer.