Osteosarcoma (OSA) is the most common pediatric malignant bone tumor. Although surgery together with neoadjuvant/adjuvant chemotherapy has improved survival for localized OSA, most patients develop recurrent/metastatic disease with a dismally poor outcome. Therapeutic options have not improved for these OSA patients in recent decades. As OSA is a rare and “orphan” tumor, with no distinct targetable driver antigens, the development of new efficient therapies is still an unmet and challenging clinical need. Appropriate animal models are therefore critical for advancement in the field. Despite the undoubted relevance of pre-clinical mouse models in cancer research, they present some intrinsic limitations that may be responsible for the low translational success of novel therapies from the pre-clinical setting to the clinic. From this context emerges the concept of comparative oncology, which has spurred the study of pet dogs as a uniquely valuable model of spontaneous OSA that develops in an immune-competent system with high biological and clinical similarities to corresponding human tumors, including in its metastatic behavior and resistance to conventional therapies. For these reasons, the translational power of studies conducted on OSA-bearing dogs has seen increasing recognition. The most recent and relevant veterinary investigations of novel combinatorial approaches, with a focus on immune-based strategies, that can most likely benefit both canine and human OSA patients have been summarized in this commentary.

Apocrine gland anal sac adenocarcinoma (AGASACA) is locally aggressive and highly metastatic to regional lymph nodes. The aim of this study was to evaluate the prognostic significance of Ki67 in surgically excised AGASACA. Prognostic impact of size, regional lymph nodes metastasis, hypercalcemia, histologic pattern, mitotic count, necrosis, inflammatory and lympho-vascular invasion, anisokaryosis and anisocytosis was also evaluated. Thirty-five dogs were included, twenty-four of which also had metastatic lymph nodes. When the entire population was evaluated, only metastatic disease spread to regional lymph nodes, and necrosis and inflammatory infiltration were correlated to prognosis. When only dogs with metastatic disease were evaluated, size, solid histologic pattern, presence of lymphatic and vascular invasion showed influence on prognosis. Ki67 index was not associated with survival time and disease free interval in any case. The results of this study showed that lymph nodes metastasis at diagnosis reduced disease free interval. Moreover, tumor size greater than 5.25 cm, presence of lymphatic and vascular invasion and a solid histologic pattern were associated with a shorter survival time in dogs with metastasis to regional lymph nodes. Ki67 expression was not significantly associated with prognosis, therefore it could not be considered as a prognostic factor in this tumor type, while the role of hypercalcemia remained unclear.

Saliva is an irritant of the subcutaneous tissue, thus causing the development of a non-epithelial reactive pseudocapsule. Metaplastic ossification of the pseudocapsule is a condition rarely described in the veterinary literature. The main causes of calcification are trauma, tumours, various chronic inflammatory conditions and fibrodysplasia ossificans progressiva. The aim of the present case series was to describe three dogs affected by a calcified salivary mucocele. The medical records of dogs affected by a cervical sialocele were retrospectively evaluated, and three cases met the inclusion criteria. All the dogs in this study were referred to the Veterinary Teaching Hospital (VTH) of the Department of Veterinary Sciences of the University of Turin (Turin, Italy) for a large solid mass in the intermandibular region. The diagnosis of a mucocele was confirmed clinically by centesis and by radiography or CT. Complete excision of both the pseudocyst and the ipsilateral mandibular/monostomatic sublingual salivary gland was performed in all cases. The histological report showed large areas of bone metaplasia within the pseudocapsule and chronic sialadenitis. Based on this limited case series, complete excision of the pseudocyst and a concurrent sialoadenectomy provided an effective treatment for this rare salivary mucocele disorder.

Dogs with benign intra-pelvic rectal or vaginal masses show symptoms indicating compression on the adjacent organs. Clinical signs usually develop late when the lesion is large enough to interfere functionally. The dogs were referred for severe fecal and/or urinary tenesmus. The data collected included signalment, clinical signs, results of physical examination, pre-surgical diagnostic tests, surgical technique used, surgical complications and histological findings. Digital rectal and vaginal examination allowed the detection of a mass occupying space in the pelvic cavity in all patients. Abdominal ultrasonography and/or total body computed tomography (CT) were used to better characterize the lesion and to exclude a metastatic spread of the tumor in case of malignancy. A dorsal approach to the rectum, a dorsal episiotomy, a midline celiotomy, and a combined perineal and abdominal approach were performed to remove the mass. No postoperative complications were observed. Benign and well-differentiated malignant mesenchymal neoplasms were histologically diagnosed. As a consequence of the chronic urethral compression caused by the mass, urinary incontinence and/or urinary retention were observed for a few postoperative days. Fecal tenesmus resolved in all cases in the immediate postoperative period. The dogs’ quality of life quickly improved after surgery, especially considering the serious and life-threatening pre-surgical clinical conditions. Both the recovery time after surgery and overall survival were also evaluated.

Canine oral malignant melanoma (OMM) is an aggressive, spontaneously occurring tumor carrying a poor to guarded prognosis and relatively limited therapeutic strategies. In this landscape, chondroitin sulfate proteoglycan (CSPG)4 represents a promising immunotherapeutic target. The objective of this bi-center prospective study was to examine the clinical outcome of OMM-bearing dogs treated with surgery and adjuvant electroporation using a DNA vaccine (HuDo-CSPG4) encoding both human (Hu) and canine (Do) portions of CSPG4 through two different vaccination protocols. Dogs with stage I-III surgically resected CSPG4-positive OMM underwent HuDo-CSPG4 plasmid electroporation starting at the 3^rd-4^th post-operative week; electrovaccination was repeated after 2 weeks. In protocol 1, electrovaccination was then delivered monthly while in protocol 2, electrovaccination was performed monthly four additional times followed by semestral boosters. The survival rates of HuDo-CSPG4-vaccinated dogs were estimated and compared with a control group treated with surgery alone. Significantly longer overall survival times were observed in HuDo-CSPG4 vaccinated dogs as compared with non-vaccinated controls. Dogs receiving protocol 2 showed similar outcomes to those of dogs undergoing protocol 1, despite fewer vaccinations. The comparable humoral response against CSPG4 resulting from the administration of protocol 1 and 2 appears to have similar clinical relevance, highlighting protocol 2 as the optimal vaccination schedule.

Objectives: To evaluate the feasibility and the complications following single or double random mucosal rotating (transposition or interpolation) flaps for the closure of rostral to mid maxillary defects in dogs.Materials and Methods: Medical records of dogs treated with single or double random mucosal rotating flaps after maxillectomy for oral lesions or traumatic loss of tissue, were evaluated. Clinical findings, surgery performed, outcome and postoperative complications (major and minor) were extracted.Results: Twenty‐six client‐owned dogs were retrospectively included. Dogs underwent maxillectomy for canine acanthomatous ameloblastomas (9), oral squamous cell carcinomas (4), peripheral odontogenic fibromas (4), oral melanomas (3), oral fibrosarcomas (2), dentigerous cysts (2) and oral osteosarcoma (1) and trauma resulting in an oronasal fistula (1). Twenty‐three dogs underwent a single transposition or interpolation flap and three dogs were treated with a double transposition flap. Postoperative complications, including dehiscence or flap necrosis, occurred in six dogs.Clinical Significance: Random mucosal rotating (transposition or interpolation) flaps are versatile when used to close rostral maxillary defects in dogs. Postoperative complications appear to be more likely when these flaps are used to close mid maxillary defects.