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Canine mammary tumors (CMTs) represent a significant health concern in dogs, with a high incidence among intact female dogs. CMTs are a promising comparative model for human breast cancer, due to sharing several pathophysiological features. Additionally, CMTs have a strong genetic correlation with their human counterpart, including the expression of microRNAs (miRNAs). MiRNAs are a class of non-coding RNAs that play important roles in post-translational regulation of gene expression, being implicated in carcinogenesis, tumor progression, and metastasis. Moreover, miRNAs hold promise as diagnostic, prognostic, and metastatic biomarkers. Understanding the molecular mechanisms underlying CMTs is crucial for improving diagnosis, prognosis, and monitoring of treatments. Herein, we provide a comprehensive overview of the current knowledge on miRNAs in CMTs, highlighting their roles in carcinogenesis and their potential as biomarkers. Additionally, we highlight the current limitations and critically discuss the overarching challenges in this field, emphasizing the need for future research to translate miRNA findings into veterinary clinical practice., (© 2024. The Author(s).)

Although studies have determined the neutrophil-lymphocyte ratio (NLR) to be a useful prognostic predictor in various human cancers, little is known regarding its preoperative prognostic significance in feline mammary tumors (FMTs). Thus, the present study aimed to determine the prognostic utility of preoperative peripheral blood NLR in malignant FMTs. Accordingly, medical records of 34 cats that had undergone mastectomy were searched, after which those histopathologically confirmed to have malignant FMTs were included. Univariate analysis was used to determine the effect of each variable on one-year survival time. Factors determined to be significant during univariate analysis were subsequently included for multivariate analysis. Receiver operating characteristic analysis was used to assess the accuracy of the tests for predicting one-year survival. Univariate analysis showed that a high NLR and large tumor size were significantly associated with shorter survival times (P < 0.01, for both). No significant differences in other factors were observed. Multivariate analysis showed that a high NLR (hazard ratio, 25.03; 95% confidence interval, 2.98-210.40; P < 0.01), but not tumor size and age, was an independent prognostic factor for poor outcomes. The sensitivity and specificity of the NLR (cut-off, 5.67) for predicting one-year survival were 93.8% and 88.9%, respectively. This study suggests that the NLR could potentially be used as a preoperative prognostic factor in FMTs. Preoperative NLR may help to establish therapeutic modalities by allowing prognostic evaluation among cats with mammary tumors., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

1,2-dichloroethane (DCE or EDC) is a chlorinated hydrocarbon used as a chemical intermediate, including in the synthesis of polyvinyl chloride. Although DCE has induced tumors in both rats and mice, the overall weight-of-evidence suggests a lack of in vivo mutagenicity. The present study was conducted to explore a potential mode of action further for tumor formation in rat mammary tissue. Fischer 344 rats were exposed to target concentrations of 0 or 200 ppm of DCE vapors (6 hours/day, 7 days/week) for at least 28 days; 200 ppm represents a concentration of ~20% higher than that reported to induce mammary tumors. Endpoints examined included DNA damage (via Comet assay), glutathione (reduced, oxidized and conjugated), tissue DNA adducts, cell proliferation and serum prolactin levels. Exposure to DCE did not alter serum prolactin levels with consistent estrous stage, did not cause cell proliferation in mammary epithelial cells, nor result in histopathological alterations in the mammary gland. DNA adducts were identified, including the N 7 -guanylethyl glutathione adduct, with higher adduct levels measured in liver (nontumorigenic target) compared with mammary tissue isolated from the same rats; no known mutagenic adducts were identified. DCE did not increase the Comet assay response in mammary epithelial cells, whereas DNA damage in the positive control (N-nitroso-N-methylurea) was significantly increased. Although the result of this study did not identify a specific mode of action for DCE-induced mammary tumors in rats, the lack of any exposure-related genotoxic responses further contributes to the weight-of-evidence suggesting that DCE is a nongenotoxic carcinogen., (© 2020 John Wiley & Sons, Ltd.)

Tumor-associated macrophages (TAMs) have been involved in growth and metastases of human and canine mammary tumors. However, the prognostic importance of TAM specific location in canine mammary tumors (CMT) was not evaluated. In this study, we evaluated the potential role of TAMs in specific histologic locations - intratumoral (iTAM) and stromal (sTAM), as well as total macrophage (tTAM) counts - as prognostic indicators in CMT. Clinicopathologic data from 66 animals with mammary carcinoma and their tumors were used in this study. Samples were stained with anti-macrophage antibody for subsequent TAM count. High levels of iTAM, sTAM, and tTAM were related with advanced clinical stage and vascular invasion. Additionally, tTAM revealed a relation with larger tumor size, while high levels of sTAM and tTAM were also correlated with node metastasis and a poor prognosis based on survival analysis. CMT with aggressive features can reveal higher TAM counts. TAMs are associated with vascular invasion and nodal metastasis, and sTAM and tTAM counts are correlated with overall survival, suggesting they could be used as prognostic indicators in canine mammary carcinomas., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death amongst women with cancer. One novel therapy used for breast cancer treatment constitutes non-contact electric fields and is called electro-capacitive cancer therapy (ECCT) with intermediate frequency and low intensity. The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4, and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68-positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was found to have decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells, leading to tumor cell death and potentially helping wounds heal., Competing Interests: No competing interests were disclosed., (Copyright: © 2021 Alamsyah F et al.)

n-3 long chain Polyunsaturated Fatty Acids (n-3 LCPUFA) have been shown to improve the efficacy of conventional chemotherapies used for breast cancer treatment. In addition to their reported ability to increase the chemosensitivity of cancer cells, we hypothesized that n-3 LCPUFA could induce a remodeling of the vascular network in mammary tumors. A contrast-enhanced ultrasound method was used to monitor the vascular architecture during docetaxel treatment of mammary tumors in rats fed either a control or an n-3 LCPUFA-enriched diet (docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA)). The vascular network was remodeled in favor of smaller vessels (microvascularization), which represented 54% of the vasculature in n-3 LCPUFA tumors but only 26% in control tumors after 2 weeks of chemotherapy. Importantly, vascularization changes occurred both before and during docetaxel treatment. The density of smaller vessels quantified before chemotherapy was correlated with improved tumor size reduction by docetaxel treatment. Furthermore, transcript levels of the angiogenesis-specific genes epiregulin and amphiregulin were reduced by ~4.5- and twofold in tumors obtained from rats fed an n-3 LCPUFA-enriched diet compared to those of rats fed a control diet, respectively. Their expression levels were negatively correlated with tumor regression after chemotherapy. Taken together, this preclinical data strengthen the potential usefulness of n-3 LCPUFA as a complementary clinical strategy to improve drug efficiency via remodeling of the tumor vasculature.

Background: The angiogenesis process is regulated by many factors, such as Hypoxia-Inducible Factor-1 (HIF-1) and Vascular Endothelial Growth Factor (VEGF). Metformin has demonstrated its ability to inhibit cell growth and the LY294002 is the major inhibitor of PI3K/AKT/mTOR pathway that has antiangiogenic properties., Methods: Canine mammary tumor cell lines CMT-U229 and CF41 were treated with metformin and LY294002. Cell viability, protein and gene expression of VEGF and HIF-1 were determined in vitro. For the in vivo study, CF41 cells were inoculated in female athymic nude mice treated with either metformin or LY294002. The microvessel density by immunohistochemistry for CD31 as well as the gene and protein expression of HIF-1 and VEGF were evaluated., Results: The treatment with metformin and LY294002 was able to reduce the cellular viability after 24 hours. The protein and gene expression of HIF-1 and VEGF decreased after treatment with metformin and LY294002. In the in vivo study, there was a decrease in tumor size, protein and gene expression of HIF-1 and VEGFA, in addition to the decreasing of CD31 expression after all treatments., Conclusion: Our results demonstrate the effectiveness of metformin and LY294002 in controlling the angiogenesis process in mammary tumors by VEGF and HIF-1, the most important angiogenic markers., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The epithelial-mesenchymal transition (EMT) is a dynamic process linked to metastasis in many tumor types, including mammary tumors. In this study, we evaluated E-cadherin and vimentin immunolocalization in primary canine mammary carcinomas (20 cases) and their respective metastases, as well as their relationship with the core regulators SNAIL/SLUG. To assess the number of cells undergoing the process of EMT, we quantitated double-positive (E-cadherin + /vimentin + ) cells using immunofluorescence, via cell counting and image analysis. In addition, SNAIL/SLUG expression was evaluated by established immunohistochemical methods. Primary tumors had significantly more E-cadherin + /vimentin + co-expression than their paired respective lymph node or distant metastasis, respectively. Furthermore, the percentage of E-cadherin + /vimentin + cells in grade II and III carcinomas was significantly higher than in grade I tumors. Primary tumors had significantly higher SNAIL/SLUG expression when analyzed based on the percentage of positive cells compared with their respective distant metastases in pairwise comparisons. An inverse correlation was noted between SNAIL/SLUG immunoreactivity and percentage of E-cadherin + /vimentin + immunopositive cells in primary tumor samples when SNAIL/SLUG immunoreactivity was grouped into 2 categories (high versus low) based on percentage-positive staining. These results show a positive correlation between E-cadherin + /vimentin + cells and higher tumor grade, establish differences between primary tumor and their respective metastases, and provide further support that EMT plays a critical role in the metastasis of canine mammary carcinoma. Furthermore, these data suggest that modulation of this process could provide greater therapeutic control and provide support for further research to determine if E-cadherin + /vimentin + co-immunoreactivity imparts predictive value in the clinical outcome of patients with canine mammary carcinomas.

Canine mammary tumours (CMTs) are one of the most common malignancies in bitches. Platelet-derived growth factor receptor (PDGFR) α and β, vascular endothelial growth factor receptor-2 (VEGFR-2) and CD117 are tyrosine kinase receptors involved in several tumours and represent suitable targets for specific therapy with toceranib phosphate. The purpose of this study was to evaluate the expression of these receptors in the pathogenesis and progression of CMTs. PDGFRα, PDGFRβ, VEGFR-2 and CD117 were expressed in 46/83 (55.4 per cent), 33/83 (39.8 per cent), 46/83 (55.4 per cent) and 32/83 (38.5 per cent) of CMTs, respectively. Immunohistochemical results showed a statistically significant loss of PDGFRα and PDGFRβ expression in simple carcinomas compared with complex/mixed carcinomas. Protein expression by western blot revealed specific bands corresponding to PDGFRα and VEGFR-2 in 3/7 and in 1/7 cell lines. Moreover, in vitro treatment showed that toceranib phosphate weakly reduced cell proliferation in one canine mammary cell line. Before considering TKR inhibitors for possible therapeutic approaches, actually further studies are necessary to evaluate the effect of these drugs on CMTs in vivo., Competing Interests: Competing interests: None declared., (© British Veterinary Association (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

The miR-200 family of microRNAs consisting of miR-141, miR-200a, miR-200b, miR-200c and miR-429 are emerging as important regulators of breast cancer progression. This family of microRNAs maintain mammary epithelial identity and downregulation of miR-200 expression has been associated with epithelial-to-mesenchymal transition in mammary tumors. Therefore, re-expression of one or more miR-200 family members in mammary tumor cells with mesenchymal characteristics may restore an epithelial phenotype including growth and metastasis suppression. To test this hypothesis, the miR-200b/200a/429 cluster was re-expressed in a murine claudin-low cell line, RJ423. Re-expression of the miR-200b/200a/429 cluster in RJ423 cells significantly suppressed the expression of Vim, Snai1, Twist1, Twist2 and Zeb1, reverted RJ423 cells to a more epithelial morphology and significantly inhibited proliferation in vitro. Moreover, the miR-200b/200a/429 cluster prevented lung metastasis in an experimental metastasis model and although tumor initiation was not prevented, re-expression of the miR-200b/200a/429 cluster induced a dormancy-like state where mammary tumors failed to grow beyond ~150 mm 3 or grew extremely slowly following intra-mammary injection. These dormant tumors contained elevated levels of collagen and were highly vascularized. Therefore, re-expression of the miR-200b/200a/429 cluster in the claudin-low mammary tumor cell line, RJ423, is sufficient to alter cell morphology, impair metastasis and induce tumor dormancy., (Copyright © 2018 Elsevier Inc. All rights reserved.)

We determined cytologic features of histologically confirmed subcentimeter canine mammary tumors (CMTs) to determine reasonable criteria for an accurate cytologic diagnosis. Fifty-three CMTs from 28 bitches were included. All cytologic samples were collected by ultrasound-guided fine-needle aspiration biopsy, stained with May-Grünwald/Giemsa, and retrospectively evaluated using a scoring system established for 18 cytologic features. Mean nuclear area (MNA) was also measured for each sample by a computer-assisted program. Based on the histologic diagnosis, CMTs were divided into 2 groups: malignant tumors (25) and benign lesions (15). Data were statistically analyzed using Fisher and Mann-Whitney tests. Chromatin pattern ( p < 0.05) and macrophage infiltration ( p < 0.05) were significantly different between the groups. Median MNA was significantly ( p < 0.05) larger in malignant tumors. The evaluation of these cytologic features in subcentimeter CMTs may increase the sensitivity of cytology.

Histopathology is considered the gold standard diagnostic method for canine mammary tumors. In 2011, a new histologic classification for canine mammary tumors was proposed. The present study was a 2-year prospective study that validated the 2011 classification as an independent prognostic indicator with multivariate analysis in a population of 229 female dogs, identifying subtype-specific median survival times (MST) and local recurrence/distant metastasis rates. Dogs with benign tumors and carcinoma arising in benign mixed tumors all had an excellent prognosis. Dogs with complex carcinoma and simple tubular carcinoma also experienced prolonged survival. Those with simple tubulopapillary carcinoma, intraductal papillary carcinoma, and carcinoma and malignant myoepithelioma had a more than 10-fold higher risk of tumor-related death. The prognosis was even worse for adenosquamous carcinoma (MST = 18 months), comedocarcinoma (MST = 14 months), and solid carcinoma (MST = 8 months). The most unfavorable outcome was for anaplastic carcinoma (MST = 3 months) and carcinosarcoma (MST = 3 months), which also had the highest metastatic rates (89% and 100%, respectively). Adenosquamous carcinoma exhibited the highest local recurrence rate (50%). In the same canine population, the tumor diameter was recognized as a strong predictor of local recurrence/distant metastasis and an independent prognosticator of survival in the multivariate analysis. Excision margins were predictive only of local recurrence, whereas lymphatic invasion and histologic grade were predictive of local recurrence/distant metastasis and survival, although only in univariate analyses. In conclusion, this study validated the 2011 classification scheme and provided information to be used in the clinical setting and as the basis for future prognostic studies.

Breast cancer is the most common malignancy in women worldwide. Several studies have suggested that exercise training may decrease the risk of breast cancer development. This study aimed to evaluate the effects of long-term exercise training on mammary tumorigenesis in an animal model of mammary cancer. Fifty female Sprague-Dawley rats were randomly divided into four groups: MNU sedentary, MNU exercised, control sedentary and control exercised. Animals from MNU groups received an intraperitoneal administration of N-methyl-N-nitrosourea (MNU). Animals were exercised on a treadmill during 35 weeks. When animals were killed, blood samples were collected to determine the hematocrit and to perform the biochemical analysis. Mammary tumors were collected and histologically evaluated; the expression of ERs α and β was evaluated in tumor sections by immunohistochemistry. All survived animals from both MNU groups developed mammary tumors. The number of mammary tumors (p > 0.05) and lesions (p = 0.056) was lower in MNU exercised than in MNU sedentary animals. MNU exercised animals showed lower number of malignant lesions than MNU sedentary animals (p = 0.020). C-reactive protein serum concentration was lower in exercised animals; however, the levels of 17-β estradiol were higher in exercised animals. Tumors from exercised animals exhibited higher expression of ER α than tumors from sedentary animals (p < 0.05). This study analyzes the impact of the longest exercise training protocol on mammary tumorigenesis ever performed. We concluded that the lifelong endurance training has beneficial effects on mammary tumorigenesis in female rats (reduced the inflammation, the number of mammary tumors and lesions, and histological grade of malignancy). Additionally, the mammary tumors from MNU exercised group exhibited higher immunoexpression of ER α that is an indicator of well-differentiated tumors and better response to hormone therapy.

Background/aim: The effects of mast cells on carcinogenesis is not yet fully understood. This work aimed to disclose the role of mast cells in mammary carcinogenesis in a rat model., Materials and Methods: Mammary tumors were induced by the administration of N-methyl-N-nitrosourea (MNU) in three groups of rats. Animals from one group were treated with ketotifen immediately after MNU administration, and animals from another only received ketotifen after the development of the first mammary tumor. The biochemical profile was determined. Mammary tumors were evaluated by histopathology and immunohistochemistry., Results: Animals from ketotifen-treated groups developed fewer mammary tumors, higher number of mammary lesions and had lower histamine levels when compared to non-treated animals. Animals treated with ketotifen immediately after MNU exhibited the lowest proliferative and apoptotic indexes., Conclusion: The mainly positive effect of the inhibition of mast cell degranulation seems to be the reduction of tumor proliferation when the mast cell degranulation was inhibited before tumor development., (Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Plasmonic photothermal therapy (PPTT) was introduced as a promising treatment of cancer. This work was conducted to evaluate the cytotoxic effect of intratumoral (IT) injection of 75μg gold nanorods (GNRs)/kg of body weight followed by direct exposure to 2 w/cm 2 near infra-red laser light for 10min on ablation of mammary tumor in 10 dogs and 6 cats. Complete blood count (CBC), liver and kidney function were checked before the start of treatment and one month after injection of GNRs. Results showed that 62.5% (10/16), 25% (4/16) and 12.5% (2/16) of treated animals showed complete remission, partial remission and no response, respectively. Tumor was relapsed in 4 cases of initially responding animals (25%). Overall survival rate was extended to 315.5±20.5days. GNRs have no toxic effect on blood profile, liver or kidney functions. In conclusion, GNRs can be safely used for treatment of mammary tumors in dogs and cats., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Cyclooxygenase-2 (Cox-2) enzyme participates in different steps of the carcinogenetic process and in canine mammary tumours (CMTs), a high expression of Cox-2 is associated with malignancy and tumour angiogenesis. The objectives of the study were to evaluate the disease-free survival (DFS) and overall survival (OS) of a Cox-2 inhibitor as adjuvant therapy in dogs with highly malignant (HM)-CMTs and compare it with that of dogs treated with chemotherapy and with control dogs. Twenty-eight dogs were prospectively included. After surgery, dogs were alternatively allocated into two treatment groups (chemotherapy with mitoxantrone n=8; Cox-2 inhibitor, firocoxib n=7). Control group (n=13) included dogs whose owners rejected adjuvant therapy. All dogs were followed up for two years or until death. The DFS was significantly higher in dogs that received adjuvant treatment (mitoxantrone or firocoxib) (P=0.030) than in control dogs. Dogs on firocoxib treatment had significantly higher DFS (P=0.015) and OS (P=0.048) than control dogs. The DFS and OS of dogs on mitoxantrone treatment were not statistically different from controls. In conclusion, this study supports the use of firocoxib for the treatment of HM-CMTs. Further studies are needed to compare the efficacy of chemotherapy drugs versus Cox-2 inhibitors as adjuvant treatment in these cases., (British Veterinary Association.)

Although mammary gland tumors (MT) are the most-common type of tumor in intact female dogs, there is little information about their incidence in dog population. Data on MT in female dogs was retrieved from the Animal Tumor registry of dogs and cats of Venice and Vicenza provinces during 2005-2013 and was analyzed to visualize crude incidence rates by breed and across age categories. Overall, 2744 mammary tumors were reported accounting for 54% of all tumors in female dogs. The annual incidence rate (IR) was 250 cases per 100,000 dogs. The most frequent malignant tumors were complex carcinomas, consisting of both epithelial and myoepithelial tissues (IR=71.89), and simple carcinomas (IR=62.59). The MT incidence rate increased through the study period; particularly in the last 4 years, and malignant neoplasms occurred more frequently (70%) than the benign counterparts (30%). Seventy-four percent of tumors were diagnosed in intact females, and the mean age at diagnosis was significantly higher for spayed dogs than for intact ones. MT were less frequent in dogs younger than 6 years and increased up to approximately 60% for ages between 8 and 13 years. The purebred dogs had a higher probability to have a malignant neoplasm than mixed-breed dogs, particularly in dogs younger than 7 years, and the Samoyed, Dobermann, Schnauzer and Yorkshire Terrier breeds were more inclined to develop malignant MT. The incidence of MT in dogs is increasing, and IRs are comparable to that in women. The epidemiological similarities between dogs and women support the validity of canine MT as a model for human breast cancer., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: As in women, regional lymph node status impacts survival in dogs with malignant mammary tumors. However, few studies have evaluated regional lymph node metastases in dogs with malignant mammary gland tumors., Objectives: To estimate overall survival based on the assessments of the lymph node status and the morphologic and morphometric features in female dogs with malignant mammary gland tumors., Materials and Methods: In total, 178 lymph nodes from 97 female dogs were assessed and reviewed, and after confirmation by immunohistochemistry (IHC), 161 lymph nodes were selected for analysis of metastases. Animals were considered metastasis-free (negative lymph nodes) only after IHC analysis for cytokeratin AE1/AE3. The number of positive lymph nodes, the number of metastatic foci, the maximum diameter and the area of metastasis were analyzed, and estimates of overall survival were made., Results: Dogs with metastasis had lower mean survival than those with metastasis-free regional lymph nodes, showing a direct relationship between the number of affected lymph nodes and shorter survival. However, histologic analysis of the lymph nodes identified lower survival rates in animals with macrometastases and isolated tumor cells, areas of metastasis >20.11 mm², and metastatic diameters >7.32 mm., Conclusion: The identification of ≥1 lymph nodes positive for metastasis and morphometric characterization of lymphatic metastases indicate the prognostic relevance of lymph nodes status in dogs with mammary tumors., (Copyright © 2015 by the American College of Veterinary Internal Medicine.)

We have previously indicated that the ideal animal tumor model should mimic the human disease. This means that the investigator should be able to ascertain the influence of host factors on the initiation of tumorigenesis, mimic the susceptibility of tumor response based on age and reproductive history, and determine the response of the tumors induced to chemotherapy. The utilization of experimental models of mammary carcinogenesis in risk assessment requires that the influence of ovarian, pituitary, and placental hormones, among others, as well as overall reproductive events are taken into consideration, since they are important modifiers of the susceptibility of the organ to neoplastic development. Several species, such as rodents, dogs, cats, and monkeys, have been evaluated for these purposes; however, none of them fulfills all the criteria specified previously. Rodents, however, are the most widely used models; therefore, this work will concentrate on discussing the rat rodent model of mammary carcinogenesis., (© 2014 by The Author(s).)

In the present study, 13 clinical cases of canine mammary adenocarcinoma were evaluated in order to understand the effect of Tarantula cubensis extract (TCE) on tumor tissue. Punch biopsies were taken from the tumors before treatment with TCE. Subcutaneous injections of TCE were administered three times at weekly intervals (3 mL per dog). Between days 7 and 10 after the third injection, the tumor masses were extirpated by complete unilateral mastectomy. Pre- and post-treatment tumor tissues were immunohistochemically assessed. The expression of B-cell lymphoma 2 (Bcl-2) was found to be higher in pre-treatment compared to post-treatment tissues (p < 0.01) whereas Ki-67 expression was lower in post-treatment tissues (p < 0.01). No significant differences in fibroblast growth factor or vascular endothelial growth factor expression were observed between pre- and post-treatment tissues (p > 0.05). The apoptotic index was determined to be low before treatment and increased during treatment. These results suggest that TCE may be effective for controlling the local growth of canine mammary adenocarcinoma by regulating apoptosis.

Cloning and sequencing of the progesterone receptor gene in dogs have revealed 2 isoforms, A and B, transcribed from a single gene. Distribution of isoforms A and B in canine mammary lesions has hitherto been investigated only by Western blot analysis. This study analyzed progesterone receptor and its isoforms in formalin-fixed, paraffin-embedded tissue samples from canine mammary lesions (4 dysplasias, 10 benign tumors, and 46 carcinomas) using 1-step SYBR Green quantitative real-time polymerase chain reaction (RT-qPCR). Progesterone receptor was expressed in 75% of dysplasias, all benign tumors, and 59% of carcinomas. Carcinomas, and particularly simple epithelial-type carcinomas, displayed the lowest levels of expression. A high rate of agreement was recorded between RT-qPCR and immunohistochemical labeling. Isoforms A and B were successfully amplified, with correlation coefficients of 0.99 and amplification efficiencies close to 2, and were expressed in all lesion types analyzed. Predominance of A over B expression was observed in carcinomas and complex adenomas. Low-grade tumors exhibited higher progesterone receptor messenger RNA (mRNA) levels, but no difference was observed in the expression of isoform A versus B. Analysis of progesterone receptor mRNA isoforms by RT-qPCR was successful in routinely formalin-fixed, paraffin-embedded tissue samples and enabled the distribution of isoforms A and B to be identified for the first time in dysplasias, benign tumors, and malignant tumors of the canine mammary gland. These findings will facilitate future research into the role of progesterone receptor isoforms in the progression of canine mammary tumors., (© The Author(s) 2013.)

When compared with the canine species, feline mammary tumors (FMTs) are much less heterogeneous, with a predominance of simple malignant neoplasm. Benign FMTs are rare, and it is unclear if complex and mixed tumors exist in the feline. In this study, we selected for immunohistochemical analyses 12 FMTs that had unusual histologic features. A group of 8 (2 benign and 6 malignant) FMTs showed a biphasic epithelial/myoepithelial population and a very regular cord-like distribution in a "Chinese lettering" pattern, within ectatic ducts. A second group (2 benign and 2 malignant) had an intraductal epithelial papillary growth pattern with a basally located monolayer of myoepithelial cells and a supporting fibrovascular stroma. The myoepithelial component always produced a standard immunohistochemical signature. All malignancies were grade I, and the subjects were all alive at 1 year postdiagnosis. On the basis of their morphology, we propose that they be classified as feline ductal adenoma/carcinoma and feline intraductal papillary adenoma/carcinoma, respectively. They overlap with their canine counterparts and lack the typical myoepithelial differentiation patterns seen in canine complex neoplasms, and therefore, the term complex should be avoided in felines. This study will add new information on FMT classification and be useful for prognostic studies.