Melanoma of the dog and cat: consensus and guidelines.

Melanoma of the dog and cat poses a clinical challenge to veterinary practitioners across the globe. As knowledge evolves, so too do clinical practices. However, there remain uncertainties and controversies. There is value for the veterinary community at large in the generation of a contemporary wide-ranging guideline document. The aim of this project was therefore to assimilate the available published knowledge into a single accessible referenced resource and to provide expert clinical guidance to support professional colleagues as they navigate current melanoma challenges and controversies. Melanocytic tumors are common in dogs but rare in cats. The history and clinical signs relate to the anatomic site of the melanoma. Oral and subungual malignant melanomas are the most common malignant types in dogs. While many melanocytic tumors are heavily pigmented, making diagnosis relatively straightforward, melanin pigmentation is variable. A validated clinical stage scheme has been defined for canine oral melanoma. For all other locations and for feline melanoma, TNM-based staging applies. Certain histological characteristics have been shown to bear prognostic significance and can thus prove instructive in clinical decision making. Surgical resection using wide margins is currently the mainstay of therapy for the local control of melanomas, regardless of primary location. Radiotherapy forms an integral part of the management of canine oral melanomas, both as a primary and an adjuvant therapy. Adjuvant immunotherapy or chemotherapy is offered to patients at high risk of developing distant metastasis. Location is the major prognostic factor, although it is not completely predictive of local invasiveness and metastatic potential. There are no specific guidelines regarding referral considerations for dogs with melanoma, as this is likely based on a multitude of factors. The ultimate goal is to provide the best options for patients to extend quality of life and survival, either within the primary care or referral hospital setting.

In vivo exposure of the bladder using a non-invasive high intensity focused ultrasound toroidal transducer.

A toroidal high-intensity focused ultrasound (HIFU) transducer was used to expose normal bladder wall tissues non-invasively in vivo in a porcine model in order to investigate the potential to treat bladder tumors. The transducer was divided into 32 concentric rings with equal surface areas, operating at 2.5 MHz. Eight animals were split into two groups of 4. In the first group, post-mortem evaluation was performed immediately after ultrasound exposure. In the second group, animals survived for up to seven days before post-mortem evaluation. The ultrasound imaging guided HIFU device was hand-held during the procedure using optical tracking to ensure correct targeting. One thermal lesion in each animal was created using a 40 s exposure at 80 acoustic Watts (free-field) in the trigone region of the bladder wall. The average (±Standard Deviation) abdominal wall and bladder wall thicknesses were 10.3 ± 1.4 mm and 1.1 ± 0.4 mm respectively. The longest and shortest axes of the HIFU ablations were 7.7 ± 2.9 mm and 6.0 ± 1.8 mm, respectively, resulting in an ablation of the whole thickness of the bladder wall in most cases. Ablation were performed at an average depth (distance from the skin surface to the centre of the HIFU lesion) of 42.5 ± 3.8 mm and extended throughout the thickness of the bladder. There were two cases of injury to tissues immediately adjacent to the bladder wall but without signs of perforation, as confirmed by histological analysis. Non-invasive HIFU ablation using a hand-held toroidal transducer was successfully performed to destroy regions of the bladder wall in vivo.

The Prognostic Role of Preoperative Hematological and Inflammatory Indices in Canine Appendicular Osteosarcoma.

Hematological indices play a prognostic role in human osteosarcoma (OSA), but data are limited in dogs. The aim of this retrospective multicentric cohort study was to investigate the prognostic significance of pre-operative hematological/inflammatory indices in a cohort of client-owned dogs with appendicular OSA receiving standardized treatment. Cut-offs associated with progression-free survival (PFS) for pre-operative hematological values/ratios were established using the minimal p-value approach. Historical prognostic factors were also assessed. Statistical analyses were performed for the whole population and after the exclusion of sighthounds. Fifty-nine dogs were included (13 were sighthounds). Multivariable analysis revealed that a low neutrophil count (<4.37 × 109/L, HR0.28, CI 95% 0.13-0.61, p = 0.001), a high red blood cell count (≥7.91, HR3.5, CI 95% 1.56-7.9, p = 0.002), and a proximal humerus location (HR3.0, CI 95% 1.48-6.1, p = 0.002) were associated with shorter PFS. In the sighthound-only population, only OSA location was significantly associated with PFS in univariable analysis. When sighthounds were excluded, a low neutrophil count, a low monocyte count, and a proximal humerus location were associated with shorter PFS, in multivariable analysis. Neutrophil count and possibly monocyte and red blood cell counts can be useful prognostic markers in canine OSA treated with amputation and adjuvant carboplatin. However, not all indices are appropriate in sighthounds.

Patterns of nodal metastases, biological behaviour and prognosis of canine mast cell tumours of the pinna: A multi-institutional retrospective study.

Canine cutaneous mast cell tumours (cMCTs) of the pinna have been associated with an aggressive biological behaviour, although data remain scarce. The knowledge acquired over the past years on histologic gradings, and the value of lymph node (LN) staging, may help in better characterizing this anatomical presentation. The first aim was to describe the frequency, location, and histologic appearance of LN metastases in cMCT of the pinna. A second aim was to evaluate prognosis. Medical records of dogs with cMCT of the pinna, that underwent tumour and sentinel (SLN) or regional LN (RLN) excision, were reviewed. The influence of potential prognostic variables on time to progression (TTP) and tumour-specific survival (TSS) was investigated. Thirty-nine dogs were included: 19 (48.7%) had Kiupel high-grade (K-HG) and 20 (51.3%) had low-grade (K-LG) MCTs. Eighteen (46.1%) dogs underwent SLN mapping: the superficial cervical LN was at least one of SLN in 17 (94.4%) cases. Twenty-two (56.4%) dogs had LN metastases; the superficial cervical LN was always involved. On multivariable analysis, only K-HG was associated with increased risk of progression (p = .043) and tumour-related death (p = .021). Median TTP and TSS were 270 and 370 days in K-HG, respectively; these were not reached in dogs with K-LG tumours (p < .01). cMCTs of the pinna are often K-HG and are also associated with a higher frequency of LN metastasis; however, we confirmed the independent prognostic value of histologic grading. A multimodal treatment may lead to favourable long-term outcome. Moreover, the superficial cervical LN is most often the SLN.

Timely adjuvant chemotherapy improves outcome in dogs with non-metastatic splenic hemangiosarcoma undergoing splenectomy.

Timely delivery of adjuvant chemotherapy has been shown to be advantageous in many human cancers and canine osteosarcoma. Adjuvant chemotherapy has been shown to improve outcome for canine splenic hemangiosarcoma. The aim of this retrospective study was to investigate whether timely adjuvant chemotherapy administration resulted in better outcome in dogs with non-metastatic splenic hemangiosarcoma undergoing splenectomy. Medical records were searched for dogs with non-metastatic, splenic hemangiosarcoma that received splenectomy and adjuvant chemotherapy. The number of days from surgery to the first chemotherapy dose (StoC) was evaluated to identify the cut-off value associated with the best survival advantage. StoC and other possible prognostic factors were tested for influence on time to metastasis (TTM) and overall survival (OS). Seventy dogs were included. Median StoC was 20 days (range: 4-70). The time interval associated with the greatest survival benefit was 21 days. Median TTM and OS of dogs with StoC ≤ 21 days were significantly longer than those with StoC >21 days (TTM: 163 vs. 118 days, p = .001; OS: 238 vs. 146 days, p < .001). On multivariable analysis, StoC >21 days was the only variable significantly associated with increased risk of tumour progression (HR 2.1, p = .010) and death (HR 2.3; p = .008). Starting adjuvant chemotherapy within 21 days of surgery may be associated with a survival benefit in dogs with non-metastatic splenic hemangiosarcoma, possibly due to the early targeting of newly recruited metastatic cells after surgery.

Isotretinoin treatment of 12 dogs with epitheliotropic lymphoma.

BACKGROUND: Epitheliotropic lymphoma is an uncommon cutaneous malignancy of T lymphocytes. Limited information is available regarding the treatment and outcome of dogs with this disease. OBJECTIVES: To evaluate the treatment outcome and toxicity profile of isotretinoin in dogs with epitheliotropic lymphoma. ANIMALS: Twelve dogs with a diagnosis of epitheliotropic lymphoma were included. MATERIALS AND METHODS: A medical database was searched for dogs diagnosed with epitheliotropic lymphoma and treated with isotretinoin between 2010 and 2021. Diagnosis, treatment details and tumour response were recorded for 12 dogs. RESULTS: All lesions resolved in four of 12 (33%) treated dogs. Lesions visibly improved in a further three dogs, giving a response rate of 58%. Two dogs' lesions remained unchanged and three progressed despite therapy. Adverse effects occurred in three dogs (25%), all of which were rapidly resolving or not affecting quality of life. CONCLUSION: Isotretinoin treatment was a well-tolerated and effective treatment for canine epitheliotropic lymphoma.

Contexte - Le lymphome épithéliotrope est une tumeur maligne cutanée peu fréquente des lymphocytes T. Peu d'informations sont disponibles concernant le traitement et les résultats des chiens atteints de cette maladie. Objectifs - Évaluer les résultats du traitement et le profil de toxicité de l'isotrétinoïne chez les chiens atteints de lymphome épithéliotrope. Animaux - Douze chiens avec un diagnostic de lymphome épithéliotrope ont été inclus. Matériels et méthodes - Une base de données médicale a été recherchée pour les chiens diagnostiqués avec un lymphome épithéliotrope et traités à l'isotrétinoïne entre 2010 et 2021. Le diagnostic, les détails du traitement et la réponse tumorale ont été enregistrés pour 12 chiens. Résultats - Toutes les lésions ont disparu chez quatre des 12 (33 %) chiens traités. Les lésions se sont visiblement améliorées chez trois autres chiens, donnant un taux de réponse de 58 %. Les lésions de deux chiens sont restées stables et trois ont progressé malgré la thérapie. Des effets indésirables sont survenus chez trois chiens (25 %), qui se résolvaient tous rapidement ou n'affectaient pas la qualité de vie. Conclusion - Le traitement à l'isotrétinoïne a été un traitement bien toléré et efficace du lymphome épithéliotrope canin.

Introducción - El linfoma epiteliotrópico es una neoplasia maligna cutánea poco frecuente de linfocitos T. Se dispone de información limitada sobre el tratamiento y el resultado del mismo en perros con esta enfermedad. Objetivos- evaluar el resultado del tratamiento y el perfil de toxicidad de la isotretinoína en perros con linfoma epiteliotrópico. Animales- se incluyeron 12 perros con diagnóstico de linfoma epiteliotrópico. Materiales y métodos- se buscó en una base de datos médica perros diagnosticados con linfoma epiteliotrópico y tratados con isotretinoína entre 2010 y 2021. Se reciplaron datos del diagnóstico, los detalles del tratamiento y la respuesta del tumor en 12 perros. Resultados- todas las lesiones se resolvieron en cuatro de 12 (33 %) perros tratados. Las lesiones mejoraron visiblemente en otros tres perros, con una tasa de respuesta del 58%. Las lesiones de dos perros permanecieron estables y tres progresaron a pesar de la terapia. Efectos adversos fueron reportados en tres perros (25%), todos los cuales se resolvieron rápidamente o no afectaron a la calidad de vida. Conclusión- el tratamiento con isotretinoína fue bien tolerado y eficaz para el linfoma epiteliotrópico canino.

Contexto - O linfoma epiteliotrópico é uma neoplasia cutânea de linfócitos T incomum. As informações disponíveis sobre o tratamento e evolução de cães com essa doença são limitadas. Objetivos - Avaliar a resposta ao tratamento e o perfil de toxicidade da isotretinoína em cães com linfoma epiteliotrópico. Animais - Doze cães com linfoma epiteliotrópico foram incluídos. Materiais e métodos - Pesquisou-se em um banco de dados médico os cães diagnosticados com linfoma epiteliotrópico e tratados com isotretinoína entre 2010 e 2021. Diagnóstico, detalhes do tratamento e resposta tumoral foram registrados para 12 cães. Resultados - Todas as lesões se resolveram em quatro de 12 (33%) cães. As lesões melhoraram visivelmente em outros três cães, gerando uma taxa de resposta de 58%. As lesões de dois cães permaneceram estáveis e três progrediram apesar da terapia. Ocorreram efeitos adversos em três cães (25%), mas todos apresentaram resolução rápida ou não tiveram alteração na qualidade de vida. Conclusão - O tratamento com isotretinoína foi bem tolerado e eficaz para o linfoma epiteliotrópico canino.

Canine anal sac gland carcinoma with regional lymph node metastases treated with sacculectomy and lymphadenectomy: Outcome and possible prognostic factors.

The staging system commonly used in canine anal sac gland carcinoma (ASGC) is a revised Tumour-Node-Metastasis (TNM) system published in 2007. This staging system consists in four stages and, for dogs with nodal metastases, the size of the metastatic lymph node (mLN) defines the N stage. However, we hypothesise that (1) the mLN size has no prognostic significance when the mLN can be excised, (2) a high number of mLNs is associated with poorer prognosis and (3) the measurement of the mLN on imaging is not reproducible. To investigate these hypotheses, medical records and diagnostic images of dogs with ASGC and mLN, treated with sacculectomy and lymphadenectomy, with or without chemotherapy, were reviewed. Interobserver variability for mLN measurement was assessed. Prognostic factors including mLN size and number were investigated. Time to documented progression (TDP) and disease-specific survival (DSS) were evaluated. Progression-free interval (PFI) was analysed with interval-censored data analysis. Fifty-seven dogs were included. The median PFI, TDP and DSS were 110 (95%CI 61.5-185.5), 196 (95%CI 162-283) and 340 days (95%CI 321-471), respectively. For measurement of the largest mLN, interobserver agreement was excellent but limits of agreement reached 39.7%. Neither the size of the largest mLN nor the use of adjuvant chemotherapy were associated with outcome. The number of mLNs was associated with outcome and having more than four mLNs was associated with shorter PFI (p < .001), TDP (p = .004) and DSS (p < .001). While mLN size measurement was not consistently reproducible and did not influence outcome in our cohort, number of mLNs did. Further studies are required for development of a revised staging system.

Timing of adjuvant chemotherapy after limb amputation and effect on outcome in dogs with appendicular osteosarcoma without distant metastases.

OBJECTIVE: To determine an optimal time interval between amputation and initiation of adjuvant chemotherapy (TIamp-chemo) in dogs with appendicular osteosarcoma without distant metastases and whether TIamp-chemo was associated with outcome. ANIMALS: 168 client-owned dogs treated at 9 veterinary oncology centers. PROCEDURES: Data were collected from the dogs' medical records concerning potential prognostic variables and outcomes. Dogs were grouped as to whether they received chemotherapy within 3, 5, 7, 10, 15, 20, 30, or > 30 days after amputation of the affected limb. Analyses were performed to identify variables associated with time to tumor progression and survival time after limb amputation and to determine an optimal TIamp-chemo. RESULTS: Median TIamp-chemo was 14 days (range, 1 to 210 days). Median time to tumor progression for dogs with a TIamp-chemo ≤ 5 days (375 days; 95% CI, 162 to 588 days) was significantly longer than that for dogs with a TIamp-chemo > 5 days (202 days; 95% CI, 146 to 257 days). Median overall survival time for dogs with a TIamp-chemo ≤ 5 days (445 days; 95% CI, 345 to 545 days) was significantly longer than that for dogs with a TIamp-chemo > 5 days (239 days; 95% CI, 186 to 291 days). CONCLUSIONS AND CLINICAL RELEVANCE: Findings indicated that early (within 5 days) initiation of adjuvant chemotherapy after limb amputation was associated with a significant and clinically relevant survival benefit for dogs with appendicular osteosarcoma without distant metastases. These results suggested that the timing of chemotherapy may be an important prognostic variable.

Outcome comparison between radiation therapy and surgery as primary treatment for dogs with periarticular histiocytic sarcoma: An Italian Society of Veterinary Oncology study.

Localized histiocytic sarcoma may occur as a primary lesion in periarticular tissues of large appendicular joints. Treatment options for the primary lesion include radical surgical excision, radiation therapy (RT), or both, in combination with chemotherapy for potential systemic metastases. In an effort to better characterize the time to progression (TTP) following surgical vs non-surgical approaches for periarticular histiocytic sarcoma (PAHS), a contemporary European population of affected dogs was retrospectively surveyed. Medical records were queried for newly-diagnosed PAHS cases undergoing surgery (predominantly limb amputation) or RT followed by systemic chemotherapy. Of 49 dogs, 34 underwent RT and 15 underwent surgery. All dogs received adjuvant chemotherapy. There was no statistically significant difference in TTP or overall survival between groups. The median TTP was 336 days for the operated dogs and 217 days for the irradiated dogs (P = .117). The median overall survival time was 398 days for the operated dogs and 240 days for the irradiated dogs (P = .142). On multi-variable analysis, the variables significantly associated with an increased risk of both tumour progression and tumour-related death were regional lymph node and distant metastasis at admission. Survival and local control rates following RT may be comparable to radical resection. These data may better inform shared decision-making processes between multi-disciplinary care providers and owners.

Gene Expression Profiling of B Cell Lymphoma in Dogs Reveals Dichotomous Metabolic Signatures Distinguished by Oxidative Phosphorylation.

Gene expression profiling has revealed molecular heterogeneity of diffuse large B cell lymphoma (DLBCL) in both humans and dogs. Two DLBCL subtypes based on cell of origin are generally recognized, germinal center B (GCB)-like and activated B cell (ABC)-like. A pilot study to characterize the transcriptomic phenotype of 11 dogs with multicentric BCL yielded two molecular subtypes distinguished on the basis of genes important in oxidative phosphorylation. We propose a metabolic classification of canine BCL that transcends cell of origin and shows parallels to a similar molecular phenotype in human DLBCL. We thus confirm the validity of this classification scheme across widely divergent mammalian taxa and add to the growing body of literature suggesting cellular and molecular similarities between human and canine non-Hodgkin lymphoma. Our data support a One Health approach to the study of DLBCL, including the advancement of novel therapies of relevance to both canine and human health.

Adjuvant medical therapy provides no therapeutic benefit in the treatment of dogs with low-grade mast cell tumours and early nodal metastasis undergoing surgery.

Lymph node (LN) metastasis is a negative prognostic factor in dogs with cutaneous mast cell tumours (cMCTs). While elective lymphadenectomy of metastatic LNs improves outcome, the benefit of adjuvant medical therapy in dogs with early metastatic (HN2) LNs is debated. The aim of this retrospective multicentre study was to evaluate the therapeutic benefit of adjuvant medical therapy following surgical removal of the primary low-grade cMCT (Patnaik grade 1-2 and Kiupel low-grade) and lymphadenectomy of HN2 LNs by analysing survival rates and patterns of recurrence. Seventy-three dogs were included: 42 received adjuvant medical treatment (chemotherapy and/or kinase inhibitors), and 31 did not. The median follow-up time for medically treated dogs was 619 days: two experienced local recurrence, three nodal relapse and four distant relapse. For dogs undergoing surgery only, the median follow-up time was 545 days. None of them experienced local recurrence, nodal, or distant relapse. Time to progression was significantly shorter in dogs receiving adjuvant medical treatment (P = .021). A similar tendency was observed for overall survival (P = .056). The current study shows that dogs with low-grade cMCTs, that undergo surgical excision of the primary tumour and elective lymphadenectomy of the HN2 regional LN harbour a good prognosis. The use of adjuvant medical treatment in these dogs does not seem to provide any benefit in terms of progression and survival.

Adjuvant anthracycline-based vs metronomic chemotherapy vs no medical treatment for dogs with metastatic splenic hemangiosarcoma: A multi-institutional retrospective study of the Italian Society of Veterinary Oncology.

Treatment options for dogs with metastatic (stage III) splenic hemangiosarcoma are limited. A doxorubicin-based chemotherapy regimen is commonly administered; however, there are no published data to support this practice. The aim of this study was to investigate the impact of maximum-tolerated-dose chemotherapy (MTD), metronomic chemotherapy (MC) and no adjuvant treatment on outcome in dogs with stage III splenic hemangiosarcoma undergoing splenectomy. Medical records of dogs with stage III splenic hemangiosarcoma that underwent splenectomy followed by MTD chemotherapy, MC or no adjuvant treatment were retrieved. Time to progression (TTP), survival time (ST) and toxicity were evaluated. One hundred three dogs were identified: 23 received adjuvant MTD, 38 MC and 42 were not medically treated. Overall median TTP and ST were 50 (95% confidence interval [CI], 39-61) and 55 days (95% CI, 43-66), respectively. Dogs treated with adjuvant MTD had a significantly longer TTP and ST compared with dogs receiving MC (median TTP, 134 vs 52 days, P = .025; median ST, 140 vs 58 days, P = .023, respectively). Dogs treated by splenectomy only had the shortest median TTP (28 days) and ST (40 days). However, treatment-related adverse events (AEs) were significantly more frequent in the MTD group (P = .017). The outcome for dogs with metastatic splenic hemangiosarcoma is poor. While MTD showed greater efficacy compared to MC, toxicity was higher in this group. Treatment-related AEs need to be carefully balanced against this modest survival prolongation when offering adjuvant MTD to dogs with advanced stage hemangiosarcoma.

Phenotypic and transcriptomic characterization of canine myeloid-derived suppressor cells.

Myeloid-derived suppressor cells (MDSCs) are key players in immune evasion, tumor progression and metastasis. MDSCs accumulate under various pathological states and fall into two functionally and phenotypically distinct subsets that have been identified in humans and mice: polymorphonuclear (PMN)-MDSCs and monocytic (M)-MDSCs. As dogs are an excellent model for human tumor development and progression, we set out to identify PMN-MDSCs and M-MDSCs in clinical canine oncology patients. Canine hypodense MHC class II-CD5-CD21-CD11b+ cells can be subdivided into polymorphonuclear (CADO48A+CD14-) and monocytic (CADO48A-CD14+) MDSC subsets. The transcriptomic signatures of PMN-MDSCs and M-MDSCs are distinct, and moreover reveal a statistically significant similarity between canine and previously published human PMN-MDSC gene expression patterns. As in humans, peripheral blood frequencies of canine PMN-MDSCs and M-MDSCs are significantly higher in dogs with cancer compared to healthy control dogs (PMN-MDSCs: p < 0.001; M-MDSCs: p < 0.01). By leveraging the power of evolution, we also identified additional conserved genes in PMN-MDSCs of multiple species that may play a role in MDSC function. Our findings therefore validate the dog as a model for studying MDSCs in the context of cancer.

Evaluation of the histopathological extent of neoplastic infiltration in intestinal tumours in cats.

With the exception of intestinal lymphoma, surgery is the most commonly recommended treatment for solitary feline intestinal tumours. However, there is a lack of evidence to substantiate resection margin recommendations for these tumours. The aim of this study was to add knowledge concerning resection margins for discrete intestinal masses in cats. Thirty confirmed feline intestinal tumours removed at veterinary centres across the UK from March 2017 to March 2018 underwent histological assessment at the palpable edge of the intestinal tumour and then at every 1 cm increment to the surgeon-cut tissue border in oral, aboral and mesenteric directions. Histological margin recommendations were developed for carcinoma and lymphoma tumour types and non-lymphoma intestinal tumours collectively. Seventeen intestinal lymphomas, nine carcinomas, two sarcomas and two mast cell tumours were evaluated in this study. Seven of the nine intestinal carcinomas would have been completely removed with histological margins of 4 cm in oral and aboral directions. Both sarcomas and one mast cell tumour would have been removed in their entirety with 4 cm histological margins in oral and aboral directions. There was extensive and varied microscopic invasion of intestinal tissue away from discrete intestinal lymphomas in the majority of the cases in this study. There is increasing evidence in veterinary as well as human literature supporting the role of surgical resection in the treatment of discrete intestinal lymphoma. If surgery is to be considered this study supports the removal of the gross tumour only. A histological margin of 4 cm should be considered, where possible, for intestinal masses other than lymphomas.

Evaluation of the extent of neoplastic infiltration in small intestinal tumours in dogs.

There is currently a lack of evidence-based guidance when determining surgical margins for small intestinal tumours in dogs. The purpose of this study is to help the surgeon make informed clinical decisions about margins when confronted with a small intestinal mass. Twenty-seven canine small intestinal tumours were histologically diagnosed and then had further histological assessment at every centimeter from the edge of the palpable tumour to the surgical margin in oral, aboral and mesenteric directions. In all 10 carcinomas a 3 cm tissue margin in oral, aboral and mesenteric directions would have resulted in complete tumour resection. In all 11 sarcomas a 2 cm tissue margin in oral, aboral and mesenteric directions would have resulted in complete tumour resection. Five of the six intestinal lymphomas would have required tissue margins of 4 cm or more for complete resection. Of the 21 non-lymphoma tumours assessed in this study, complete resection was achieved in all 21 (100%) with tissue margins at 3 cm from the palpable edge of the mass, 20 (95%) with tissue margins at 2 cm from the palpable edge of the mass, and 16 (76%) with tissue margins at 1 cm from the palpable edge of the mass in oral and aboral directions. All non-lymphoma canine small intestinal masses will be completely resected when tissue margins are 3 cm from the palpable edge of the mass in oral and aboral directions after fixation in formalin.

Therapeutic impact of regional lymphadenectomy in canine stage II cutaneous mast cell tumours.

Lymph node (LN) metastasis in canine cutaneous mast cell tumours (cMCTs) is a well-known negative prognostic factor. The role of lymphadenectomy in the treatment of stage II disease remains controversial because of its uncertain therapeutic benefit. Aim of this retrospective study was to investigate the impact of lymphadenectomy on tumour control and survival for dogs with stage II cMCTs. Dogs with firstly occurring, histologically confirmed cMCT with LN metastasis undergoing resection of the primary tumour and medical treatment thereafter were retrospectively enrolled. Dogs were classified into two groups: LN sampling (LNS; diagnosis of metastasis obtained by cytology) and regional LN dissection (LND; diagnosis obtained by histopathology). To determine the therapeutic value of lymphadenectomy, the characteristics of recurrence (local, nodal and distant) and survival were compared between groups. Evaluated outcome variables included signalment, anatomic location, diameter, ulceration, substage, surgical margins, Patnaik grading, Kiupel grading and medical treatment. Overall, 152 dogs were included: 81 underwent LND as part of primary surgery and 71 LNS. The median follow-up time was 409 days for LND group and 620 days for LNS group. On univariable analysis, the risk of developing local, nodal or distant relapse was significantly higher in the LNS group compared with LND (P < 0.001). On multivariable analysis, the risk of tumour progression and tumour-related death were 5.47 and 3.61 times higher in the LNS group, respectively (P < 0.001). Regional lymphadenectomy may have therapeutic value and improve prognosis in dogs with stage II cMCTs undergoing surgical removal of the primary tumour and medical treatment.

Diagnosis of anaplastic large-cell lymphoma in a dog using CD30 immunohistochemistry.

Anaplastic large-cell lymphoma or null-cell lymphoma is a clinical entity reported in people, classified according to the unique appearance of large pleomorphic cells that express CD30. Null-cell lymphoma has also been described in dogs when neither CD3 nor CD79α is expressed by the tumor. We describe a case of lymphoma in the dog in which neoplastic cells did not express routine B- or T-lymphocyte markers on flow cytometry or immunohistochemistry; however, cells immunohistochemically labeled for CD30. The dog in our case died 5 mo after initial presentation, confirming a poor prognosis. Identification of further similar cases in dogs would provide additional prognostic information for this subset of lymphomas. CD30 may also serve as a potential therapeutic target in anaplastic large-cell lymphomas.

Dissecting the regulatory microenvironment of a large animal model of non-Hodgkin lymphoma: evidence of a negative prognostic impact of FOXP3+ T cells in canine B cell lymphoma.

The cancer microenvironment plays a pivotal role in oncogenesis, containing a number of regulatory cells that attenuate the anti-neoplastic immune response. While the negative prognostic impact of regulatory T cells (Tregs) in the context of most solid tissue tumors is well established, their role in lymphoid malignancies remains unclear. T cells expressing FOXP3 and Helios were documented in the fine needle aspirates of affected lymph nodes of dogs with spontaneous multicentric B cell lymphoma (BCL), proposed to be a model for human non-Hodgkin lymphoma. Multivariable analysis revealed that the frequency of lymph node FOXP3(+) T cells was an independent negative prognostic factor, impacting both progression-free survival (hazard ratio 1.10; p = 0.01) and overall survival (hazard ratio 1.61; p = 0.01) when comparing dogs showing higher than the median FOXP3 expression with those showing the median value of FOXP3 expression or less. Taken together, these data suggest the existence of a population of Tregs operational in canine multicentric BCL that resembles thymic Tregs, which we speculate are co-opted by the tumor from the periphery. We suggest that canine multicentric BCL represents a robust large animal model of human diffuse large BCL, showing clinical, cytological and immunophenotypic similarities with the disease in man, allowing comparative studies of immunoregulatory mechanisms.

Canine soft tissue sarcoma managed in first opinion practice: outcome in 350 cases.

OBJECTIVE: To determine outcome of dogs with a diagnosis of soft tissue sarcoma managed in first opinion practice. STUDY DESIGN: Retrospective, case-controlled study ANIMALS: Dogs (n = 350) with primary occurrence of a soft tissue sarcoma. METHODS: A previously validated questionnaire was sent to all veterinarians requesting clinical information and ultimate outcome for all dogs. Histologic sections were reviewed by a single pathologist. RESULTS: Most surgeries were unplanned, with only 15 (4%) dogs having a histologic and 59 (16.8%) dogs having a cytologic diagnosis before surgery. Median survival time for all dogs was not reached with 70% proportional survival at 5 years. Local recurrence developed in 73 (20.8%) cases. The extent of resection performed was not associated with improved survival (P = .2) or tumor recurrence (P = .8). Age <8 years (χ(2) = 6.1; P = .01), tumors <5 cm in size (χ(2) = 9.6; P = .002) and discrete tumors (χ(2) = 16.6; P < .001) had improved survival outcomes. On multivariate analysis, a high tumor grade was significant for recurrence (HR 5.8; P < .001; 95% CI: 2.2-14.8). Evidence of a selection bias towards less aggressive tumors being managed in first opinion practice was confirmed. CONCLUSIONS: Wide resection margins are not the primary determinant of outcome for all soft tissue sarcoma. Veterinarians need to better understand the biologic behavior of a suspected soft tissue sarcoma before treatment to allow surgical margins to be adjusted accordingly.