Prostate cancer is one of the leading causes of cancer-related deaths worldwide, even when diagnosed at an early stage in humans and dogs. Dogs have a significant incidence of spontaneous prostate cancer, which is highly similar to human androgen-independent prostate cancer and represents a valuable model for comparative studies. Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) are the two main cannabinoids extracted from Cannabis sativa and have demonstrated antiproliferative and anti-invasive properties in different tumor types. In this study, CBD or THC-rich extracts inhibited the proliferation of two canine prostatic carcinoma cell lines, PC1 and PC2, showing an IC50 of 3.43 and 3.57 μM for CBD rich extracts, and 4.90 and 4.48 μM THC rich extracts, respectively. Cell death was also observed with both Annexin V and Propidium iodide staining for the canine cell lines. These results provide new information concerning the use of rich oil in canine PC and open a promising opportunity for further in vitro and in vivo studies to establish the mechanisms of action of these compounds using dogs as a natural model for prostatic carcinoma.

Background: Osteosarcoma is the most common primary bone tumor in humans. It is a locally aggressive tumor at the primary site, with metastasis being the main cause of death in patients. Studies on dogs have gained prominence in oncology, as they are valuable spontaneous models of osteosarcoma. In the context of natural compounds, biotoxins are attracting increasing research interest as new therapeutic agents against cancer, such as melittin, that represents 40 to 50% of the dry weight of bee venom, and studies have already shown its antitumor effects.

Mammary gland tumors are the most prevalent neoplasm in intact female dogs, and they are good natural models to study comparative oncology. Most canine mammary malignancies, as in women, are commonly refractory to conventional therapies and demand continuous new therapeutic approaches. Crotalus durissus terrificus, also called rattlesnake, has more than 60 different proteins in its venom with multiple pharmaceutical uses, such as antitumor, antiviral, and antimicrobial action. Crotoxin, a potent β-neurotoxin formed by the junction of two subunits, a basic subunit (CB-PLA₂) and an acidic subunit (crotapotin), has already been reported to have anticancer properties in different types of cancers.

Mammary gland tumors are the most common neoplasms in female intact dogs and share some biological and histopathological aspects with those in women with breast cancer, making them a good model in comparative oncology. Resveratrol is a polyphenol found in several plants, and some studies have indicated that it acts in the neoplastic process as an anticancer drug. Viscum album is a hemiparasitic plant widely used as an adjuvant treatment for cancer in some countries. Thus, this study aimed to evaluate the antitumor potential of resveratrol and homeopathic Viscum album together and separately using two previously characterized canine mammary tumor cell lines (UNESP-CM9 and UNESP-CM60). The cell viability test (MTT) was performed, which revealed an IC50 of 3.11 μl/100 ml for UNESP-CM9 and 2.993 μl/100 ml for UNESP-CM60 for Viscum album, and for resveratrol, the IC50 was 281.6 μM for UNESP-CM9 and 105.5 μM for UNESP-CM60. The combination of both natural compounds led to tumor cell death at a lower IC50. The cell migration assay demonstrated an increase in cell migration time with both treatments. UNESP-CM9 closed 35.66% of the wounds in the control group and 15.51% of the wounds in the viscum group, while UNESP-CM60 closed 39.46% of the wounds in the control group and 19.95% of the wounds in the viscum group and 2.41% of the wounds in the resveratrol group. Thus, these two compounds have antitumor potential, making them possible alternatives to conventional treatments.

Oral cancers, such as squamous cell carcinomas, constitute important diseases in veterinary patients, as they are frequently observed in pets. Their usually aggressive behavior makes it critical to characterize the clinicopathologic features that can provide useful data for decision-making. Recently, the importance of inflammatory cell infiltration in different tumor types has been highlighted due to its association with clinical findings and outcomes. Thus, this study aimed to evaluate clinicopathologic features in 62 cases of canine oral non-tonsillar squamous cell carcinomas, as well as to investigate tumor infiltration by inflammatory cells and its relation to clinical staging. Statistically significant results were observed when comparing neutrophil infiltration in stage 2 patients and animals presenting higher stages (3 and 4). Patients in stages 3 and 4 revealed lower neutrophil infiltration than stage 2 dogs. Histological grading showed differences in mitotic count between less differentiated and well/moderately differentiated neoplasms. Such features—especially those related to neutrophil infiltration and tumor staging—are relevant for the comprehension of non-tonsillar tumors, consequently aiding in decision-making in cases of canine oral squamous cell carcinoma in dogs.

Cancer is a genomic disease, with genetic and epigenetic alterations, leading to dysregulation of the cell cycle, failures in DNA repair and impaired activation of programmed cell death mechanisms. Among the various molecular targets involved in these deregulation processes, the SET oncoprotein stands out as its activity has been linked to poor prognosis, metastasis development and resistance to chemotherapy in human cancer. This study aimed to evaluate SET expression in different samples of canine neoplasms. A total of 93 canine cancer samples were obtained from the Veterinary Pathology Service, UNESP, for evaluation of SET oncoprotein using immunohistochemistry. The intensity of SET oncoprotein immunolabelling varied significantly among the different tumour types, indicating a potential association between tumour type and intensity. In contrast, the distribution pattern of SET oncoprotein immunolabelling was relatively consistent across tumour types, with no statistically significant differences observed. Melanoma, mammary carcinoma, squamous cell carcinoma, prostatic carcinoma, osteosarcoma and transmissible venereal tumour showed the highest immunolabelling intensity patterns, highlighting the importance of SET oncoprotein as a potential therapeutic target and paving the way for future studies on its use in personalized therapy.