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Background: Hypercalcemia of malignancy (HM) secondary to lymphoma in dogs has the potential to cause renal injury., Hypothesis/objectives: Characterize outcomes related to acute kidney injury (AKI) secondary to HM. We hypothesized that dogs do suffer AKI regardless of HM severity at the time of lymphoma diagnosis or relapse., Animals: Retrospective study. Twenty-nine dogs with lymphoma, HM, and azotemia (International Renal Interest Society [IRIS] grade II or higher AKI) that underwent chemotherapy were identified at 2 veterinary institutions., Methods: Logistic regression and descriptive statistical analysis were performed to evaluate data for potential prognostic factors., Results: After initiating treatment, resolution of hypercalcemia and azotemia occurred in 100% (29/29) and 79.3% (23/29) of dogs, respectively. Resolution of azotemia was influenced by serum creatinine concentration (odds ratio [OR], 0.148; Confidence interval [CI], 0.03-0.734; P = .02) and total hypercalcemia (OR, 0.36; CI, 0.14-0.93; P = .04) at diagnosis, whereas blood urea nitrogen concentration, IRIS grade, sex, and whether or not dogs were hospitalized were not significant factors. At data analysis, 13.8% (4/29) of dogs were alive or lost to follow-up. Of those dead, 4 dogs (15%) had renal disease at the time of death, 2/4 having concurrent lymphoma progression., Conclusions and Clinical Importance: Although AKI may be of clinical concern in dogs with HM secondary to lymphoma at diagnosis, death secondary to renal impairment appears to be infrequent., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Electrolyte abnormalities, especially hypernatremia, are frequent complications after transsphenoidal hypophysectomy in dogs with pituitary-dependent hypercortisolism., Objectives: To describe electrolyte abnormalities after transsphenoidal hypophysectomy and to investigate possible associations between postoperative hypernatremia and clinical and surgical variables as well as with postoperative outcome., Animals: One hundred and twenty-seven client-owned dogs., Methods: Dogs with pituitary corticotroph adenomas that underwent transsphenoidal hypophysectomy were retrospectively included. Plasma sodium and potassium concentrations were measured -2, +2, +8, +24, and +48 hours from hypophysectomy. Clinical (breed, age, body weight, skull type, urinary cortisol/creatinine ratio, percentage of suppression to dexamethasone) and surgical variables (duration of anesthesia and surgery, pituitary dimensions) were compared to the development of hypernatremia., Results: Postoperative hypernatremia developed in 46.5% (57/127) of dogs and hyponatremia in 6.3% (8/127). Plasma sodium concentration increased after surgery and peaked at 8 hours after surgery, normalizing after 24 to 48 hours. Plasma potassium concentration increased without exceeding the reference limit. No significant associations were found between clinical and surgical variables and hypernatremia, or between hypernatremia and postoperative death, long-term survival or recurrence. Surgery time was significantly longer in dogs that developed persistent diabetes insipidus (P = .02) and persistent diabetes insipidus occurred more frequently in dogs with enlarged pituitary glands (P = .01)., Conclusion and Clinical Importance: Hypernatremia remains a frequent postoperative complication after transsphenoidal hypophysectomy but did not appear to have an impact on postoperative outcome. No predisposing factor to postoperative hypernatremia was identified. Variations in plasma potassium concentrations do not seem to influence postoperative outcome., (© 2021 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Limited data exist about the use, efficacy, and prognostic factors influencing outcome when CyberKnife is used to treat dogs with intracranial neoplasia., Objectives: To determine the prognosis and associated prognostic factors for dogs that were imaged, determined to have primary intracranial tumors, and treated with CyberKnife radiotherapy., Animals: Fifty-nine dogs treated with CyberKnife radiotherapy for primary intracranial tumors., Methods: Retrospective medical record review of cases from January 2010 to June 2016. Data extracted from medical records included signalment, weight, seizure history, tumor location, tumor type (based on imaging), gross tumor volume, planned tumor volume, treatment dates, radiation dose, recurrence, date of death, and cause of death., Results: The median progression-free interval (PFI) was 347 days (range 47 to 1529 days), and the median survival time (MST) was 738 days (range 4 to 2079 days). Tumor location was significantly associated with PFI when comparing cerebrum (median PFI 357 days; range 47-1529 days) versus cerebellum (median PFI 97 days; range 97-168 days) versus brainstem (median PFI 266 days; range 30-1484 days), P = .03. Additionally, the presumed tumor type was significantly associated with MST (P < .001)., Conclusions and Clinical Importance: Use of Cyberknife and SRT might improve MST, compared with RT, in dogs with intracranial neoplasia., (© 2021 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Little is known regarding the comparative efficacy of various irradiation strategies used to treat intranasal carcinomas (INC) in cats., Objectives: Investigate outcomes and prognostic factors associated with survival for cats with INC., Animals: Forty-two cats with INC that underwent radiotherapy (RT)., Methods: Single-arm retrospective study. Medical record review for cats with INC that underwent RT at 1 of 7 veterinary RT facilities. Irradiation protocols categorized as: definitive-intent fractionated RT (FRT), definitive-intent stereotactic RT (SRT), and palliative-intent RT (PRT). Median overall survival time (OST) and disease progression-free survival (PFS; documented by advanced transverse imaging, or recurrence of symptoms) were calculated. Associations between tumor stage, RT protocol/intent, and adjunctive treatment usage and outcome were calculated., Results: Cats underwent SRT (N = 18), FRT (N = 8), and PRT (N = 16). In multivariate modeling, cats received definitive-intent treatment (DRT; FRT/SRT) had significantly longer median PFS (504 days, [95% confidence interval (CI): 428-580 days] vs PRT 198 days [95% CI: 62-334 days]; p = 0.006) and median OST [721 days (95% CI: 527-915 days) vs 284 days (95% CI: 0-570 days); p = 0.001]). Cats that underwent second DRT course at time of recurrence lived significantly longer than cats that received 1 RT course (either DRT or PRT [median OST 824 days (95% CI: 237-1410 days) vs 434 days (95% CI: 277-591 days); p = .028])., Conclusion: In cats with INC, DRT is associated with prolonged OST and PFS as compared to PRT. If tumor progression occurs, a second course of DRT should be considered., (© 2021 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Tigilanol tiglate (TT) is a novel small molecule for intratumoral treatment of nonmetastatic mast cell tumors (MCTs) in dogs. In a randomized controlled clinical study, 75% of dogs that received a single TT treatment achieved complete resolution of the MCT by 28 days, with no recurrence in 93% of dogs at 84 days. Critical to TT's efficacy was the area of the wound (tissue deficit) after slough of the necrotic tumor relative to pretreatment tumor volume., Objectives: To analyze data collected during the previous study to (a) describe wounds after slough of treated MCTs and (b) identify determinants of wound area and speed of wound healing., Methods: Wound presence, condition, and area were determined from clinical records of 117 dogs over 84 days after a single intratumoral TT treatment., Results: Tumor slough occurred 3 to 14 days after treatment, exposing granulation tissue in the wound bed. Wound area after tumor slough in general was related to pretreatment tumor volume, with maximal recorded wound area fully evident in 89% of dogs by day 7. In dogs achieving complete tumor resolution, all wounds were left to heal by secondary intention. Bandaging and other wound management interventions only were required in 5 dogs. Time to healing (ie, full re-epithelialization of treatment site) depended on wound area and location on the body, with most wounds being fully healed between 28 and 42 days after treatment., Conclusions: Wound area and healing after slough of TT-treated tumors follow a consistent clinical pattern for most dogs., (© 2021 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC. on behalf of the American College of Veterinary Internal Medicine.)

Background: Tigilanol tiglate (TT) is a novel small molecule approved by the European Medicines Agency for intratumoral treatment of mast cell tumors (MCTs) in dogs. In a randomized controlled clinical efficacy and safety study in the United States, 85 of 116 dogs that received a single TT injection achieved complete response (CR) of the treated MCT by day 28., Objective: To evaluate the durability of the TT treatment response achieved at day 28 in the U.S. study by assessing MCT recurrence at the treatment site 6 and 12 months after TT administration., Animals: Eighty-five dogs previously treated with TT., Methods: Dogs that achieved CR at day 28 were assessed retrospectively for the presence or absence of MCT at the treatment site using records from clinical visits and telephone interviews with owners. Dogs unavailable at an assessment time were considered lost-to-follow-up and data for their last assessment used in the final analysis., Results: By 12 months after TT treatment, 64 dogs remained evaluable, with 21 unavailable. Of evaluable patients, 57 (89%) remained tumor free at the treatment site and 7 (11%) had developed recurrence. All recurrences occurred within the first 6 months, predominantly (5/7, 71%) within the first 12 weeks., Conclusions and Clinical Importance: Tigilanol tiglate provided a durable long-term local response for the treatment of MCT in dogs., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC. on behalf of the American College of Veterinary Internal Medicine.)

Background: Information regarding outcome of dogs undergoing surgical management for insulinoma is based on studies of a small number of dogs., Objectives: To report the outcomes of dogs undergoing surgery as treatment for insulinoma, the prevalence of postoperative diabetes mellitus (DM) in this group and to determine if development of DM can be predicted., Animals: Forty-eight client-owned dogs, with a histopathological diagnosis of insulinoma, from three European referral hospitals., Methods: Retrospective observational study. Dogs were identified from a search of electronic hospital records. Cox's regression was used to determine factors associated with postoperative survival and relapse, and logistic regression was used to determine factors associated with the development of DM., Results: Median survival time (MST) was 372 days (range 1-1680 days), with dogs with stage I disease having the longest survival time. Stage I dogs had MST of 652 days (range 2-1680 days), whereas dogs with either stage II or III disease had MST of 320 days (range 1-1260 days; P = 0.045). Postoperative hyperglycemia was identified in 33% (16/48) of the dogs, of which 9 (19% of the total population) developed persistent DM. No factors that could be used as predictors for development of DM were identified., Conclusions and Clinical Importance: Stage of disease and postoperative hypoglycemia were associated with greater odds of relapse and decreased survival time; these could be used when discussing prognosis. In this study, postoperative DM developed more commonly than previously reported, but no factors were identified that might be useful predictors., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Toceranib phosphate (TOC) could be made widely available for treating tumors in dogs if evidence shows that TOC inhibits recurrence after surgery., Objectives: To investigate how postoperative adjuvant treatment with TOC modulates the tumor microenvironment (TME), by assessing effects on angiogenic activity, tumor-infiltrating regulatory T cells (Tregs), and intratumoral hypoxia., Animals: Ninety-two client-owned dogs were included: 28 with apocrine gland anal sac adenocarcinoma, 24 with small intestinal adenocarcinoma, 22 with lung adenocarcinoma, and 18 with renal cell carcinoma., Methods: Retrospective, multicenter study comparing time to progression (TTP) between 42 dogs treated by surgery and TOC and 50 dogs treated by surgery alone. Differences were analyzed in the expression of vascular endothelial growth factor receptor-2 (VEGFR2) and the number of Foxp3 + Tregs and hypoxia-inducible factor (HIF)-1α + cells in tumor tissues sampled at the first and second (recurrence) surgeries., Results: Median TTP for dogs treated by surgery and TOC (360 days) was higher than that for dogs treated by surgery alone (298 days; hazard ratio, 0.82; 95% confidence interval [CI], 0.65-0.96; P = .02). In dogs treated by surgery and TOC, VEGFR2 expression and the number of Tregs and HIF-1α + cells were significantly lower in tissues sampled at the second surgery than in those sampled after the first surgery. In dogs treated by surgery alone, significant differences were found between samples from the 2 surgeries., Conclusions and Clinical Importance: Toceranib phosphate could prove to be a useful postoperative adjuvant treatment because of its modulation of the TME., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Seizures are a common presenting sign in dogs with brain tumors., Hypothesis/objectives: To investigate the effect of radiotherapy on freedom from brain tumor-associated seizures and survival time in dogs., Animals: Thirty-two client-owned dogs with brain tumor-associated seizures; 18 received medical treatment and radiotherapy, 14 received medical treatment alone., Methods: Multicenter retrospective study. Baseline characteristics (seizure semiology, magnetic resonance imaging [MRI] characteristics, and treatment) and duration of seizure freedom were recorded for the 2 treatment groups. Duration of seizure freedom between groups was compared (log-rank test) using Cox's proportional hazard analysis, with baseline characteristics entered as covariates., Results: The duration of seizure freedom and survival time were significantly longer in the radiotherapy group (P < .001), with a mean of 24 months (95% confidence interval [CI], 14.3-33.8) versus 1.7 months in the control group (95% CI, 0.5-2.9) and a mean of 34.6 months (95% CI: 25.2-44.1) versus 6.2 months in the control group (95% CI, 2.6-9.7) respectively. Baseline characteristics were not associated with duration of seizure freedom after the start of treatment. In the radiotherapy group, 5 dogs were euthanized during the study period because of causes other than seizures. In the control group, recurrence of seizures was observed before death in all dogs., Conclusions and Clinical Importance: A longer period of seizure freedom and longer survival time was observed in dogs with brain tumors after radiotherapy compared to medical treatment only. The pathophysiological mechanisms of epileptogenesis and the effect of radiation therapy on seizure control are unclear to date. Further prospective studies are needed., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Rabacfosadine (RAB), a novel antineoplastic agent conditionally licensed for the treatment of lymphoma in dogs, is efficacious in both naïve and previously treated dogs. Its use in combination with L-asparaginase (L-ASP) has not been studied., Hypothesis/objectives: To evaluate the safety and efficacy of L-ASP given concurrently with RAB in dogs with relapsed multicentric lymphoma., Animals: Fifty-two dogs with relapse of lymphoma after treatment with at least 1 doxorubicin-based chemotherapy protocol., Methods: Open-label, multicenter, prospective single-arm clinical trial. Dogs were treated with RAB at 1.0 mg/kg IV every 21 days for up to a total of 5 doses. L-asparaginase was administered at 400 IU/kg SQ concurrently with the first 2 treatments of RAB., Results: The overall response rate (ORR) for all dogs was 67%, with 19 dogs (41%) achieving a complete response (CR). The median progression-free survival time (MPFS) was 63 days (range 5-428 days). Dogs experiencing a CR as their best response had an MPFS of 144 days (range 44-428 days). Adverse events were similar to previous studies evaluating single agent RAB. Failure to achieve a CR and having previously received L-ASP were negative prognostic factors on multivariate analysis., Conclusions and Clinical Importance: Concurrent RAB/L-ASP appears to be both efficacious and safe for treating relapsed multicentric lymphoma in dogs. Adverse events were most often mild and no unexpected toxicoses were observed., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: We developed previously a minimal residual disease (MRD) monitoring system in dogs with lymphoma by exploring a highly sensitive real-time PCR system., Objectives: To identify the change in MRD before clinical relapse in dogs with lymphoma that achieved complete remission after chemotherapy., Animals: Twenty dogs with multicentric high-grade B-cell lymphoma., Methods: MRD levels in peripheral blood mononuclear cells (PBMCs) were measured by real-time PCR amplifying the rearranged immunoglobulin heavy chain gene. MRD measurement and clinical assessment were performed every 2-4 weeks for 28-601 days after completion of chemotherapy. An increase in MRD was defined as an increase by more than 0.5, calculated by log₁₀ [copy number of MRD per 10⁵ PBMCs], based on the uncertainty level observed in a canine lymphoma cell line., Results: During the follow-up period, 15 dogs relapsed in 28-320 days (median, 120 days) after completion of chemotherapy. An increase in MRD was detected 2 weeks or more before relapse in 14 of the 15 dogs, but an increase in MRD before relapse could not be detected in the remaining 1 dog. The time from increased MRD to clinical relapse was 0-63 days (median, 42 days). In contrast, no increase in MRD was detected in 5 dogs that did not experience clinical relapse., Conclusion and Clinical Importance: An increase in MRD can be detected before clinical relapse in dogs with lymphoma. Application of early reinduction therapy based on an increase in MRD before clinical relapse may improve treatment outcome in canine lymphoma., (Copyright © 2011 by the American College of Veterinary Internal Medicine.)

Background: Metronomic chemotherapy with alkylating agents has been shown to suppress tumor angiogenesis and prevent tumor recurrence in some settings. The use of adjuvant lomustine (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea) administered in a metronomic fashion has not been evaluated in dogs., Hypothesis: Oral metronomic administration of lomustine will be well tolerated in dogs with spontaneously occurring malignant neoplasms., Animals: Eighty-one dogs with naturally occurring primary or metastatic tumors received metronomic administration of lomustine., Methods: Dogs were enrolled prospectively after cytological or histological diagnosis of a tumor that was unresectable, incompletely resected, refractory to chemotherapy, or metastatic. Dogs received once daily lomustine (2.84 mg/m² PO). End points of the trial were clinical, hematologic, or biochemical evidence of toxicosis, tumor progression, or death., Results: Starting dosage (median) was 2.84 mg/m² PO daily and treatment duration was 98 days (median, range, 1-770 days). The drug was discontinued in 22 dogs because of toxicoses. Toxicoses occurred in 13 dogs with gastrointestinal toxicosis, 4 dogs with thrombocytopenia, 3 dogs with increased alanine transaminase, 1 dog with neutropenia, and 1 dog with progressive azotemia. Eight dogs developed some degree of azotemia during treatment. Hepatotoxicosis was observed at a median of 265 days in 11 dogs. Thrombocytopenia was identified at a median of 432 days of administration., Conclusions and Clinical Importance: In dogs with metastatic or terminal neoplasms without renal compromise, metronomic administration of lomustine was well tolerated. This can provide a treatment strategy for dogs that do not have other standard-care treatment options, and warrants evaluation in primary therapy., (Copyright © 2011 by the American College of Veterinary Internal Medicine.)

Background: Electrochemotherapy (ECT) couples the administration of anticancer drugs with the delivery of electric pulses that increase the drug uptake through the cell membranes, resulting in an improved efficacy., Hypothesis: To evaluate the tolerability and efficacy of cisplatin (CDDP) as an ECT agent to prevent recurrence of incompletely resected mast cell tumors (MCTs)., Animals: Thirty-seven dogs., Methods: Prospective study recruiting dogs with incompletely excised MCTs as confirmed by surgeon and pathology reports. After debulking, the tumor bed and margins were infiltrated with CDDP, and then exposed to trains of biphasic electrical pulses under sedation. Five minutes after the injection of the chemotherapy agent, sequences of 8 biphasic pulses lasting 50 + 50 μs each, were delivered in bursts of 1,300 V/cm for sclerosed and of 800 V/cm for exposed lesions, with caliper or needle array electrodes, respectively. A second session was performed 1 or 2 weeks later based on clinical considerations., Results: The treatment was well tolerated with minimal adverse effects. Twenty-nine dogs had no evidence of recurrence over the 6-year study period, 6 had tumor recurrence, 1 died of multiple cutaneous MCTs, and 1 died of unrelated causes. The estimated median time to recurrence was 1,200 days. Recurrence was not observed among the long-term (> 1 year) treated dogs., Conclusions and Clinical Importance: ECT with CDDP appears effective in the treatment of incompletely resected MCT in dogs and could be a useful addition to the current options based on its low cost, limited toxicity, and ease of administration., (Copyright © 2011 by the American College of Veterinary Internal Medicine.)

Background: Continuous administration of low doses of cyclophosphamide and standard doses of cyclooxygenase-inhibiting drugs has been shown to suppress tumor angiogenesis, reverse immunosuppression, and deplete regulatory T cells in cancer models., Hypothesis: We hypothesized that continuous treatment with low-dose cyclophosphamide and full-dose piroxicam would delay tumor recurrence in dogs with soft tissue sarcomas (STS)., Animals: Eighty-five dogs with incompletely resected STS, 30 treated dogs, and 55 contemporary control dogs., Methods: Treatment outcomes in 85 dogs with incompletely resected STS were evaluated in a retrospective study. Dogs in the treatment group received continuously administered low-dose cyclophosphamide (10 mg/m2) and standard dose piroxicam (0.3 mg/kg) therapy. Time to local tumor recurrence (disease-free interval; DFI) was compared between the 30 treated dogs and 55 untreated control dogs matched for age and tumor site and grade., Results: DFI was significantly (P < .0001) prolonged for STS of all sites (trunk and extremity) in treated dogs compared with untreated control dogs. The DFI also was significantly longer in treated dogs when tumor site (trunk and extremity) was compared. Twelve treated dogs (40%) experienced mild toxicity (grade 1 and 2) at some point during treatment and 1 dog developed grade 4 cystitis. Every other day dosing was tolerated better than daily dosing., Conclusions: Metronomic therapy with cyclophosphamide and piroxicam was very effective in preventing tumor recurrence in dogs with incompletely resected STS. These findings suggest that further evaluation of this approach is warranted as adjuvant therapy in dogs with highly metastatic tumors such as osteosarcoma and melanoma.

The objectives of this study were to determine local recurrence rate, clinical outcome, and prognostic value of the number of argyrophylic nucleolar organizer regions (AgNORs), presence of proliferating cell nuclear antigen (PCNA), and number of Ki-67-positive nuclei after incomplete surgical excision of canine cutaneous grade II mast cell tumors (MCTs). This retrospective study included 30 MCTs in 28 dogs. Medical records were examined and follow-up information was obtained from owners and referring veterinarians. Only cases in which excision was incomplete and no anvcillary therapy (other than prednisone) for MCT was given were included. Paraffin-embedded tumor tissues were retrieved for AgNORs, PCNA, and Ki-67 staining. Median follow-up time was 811.5 days. Seven (23.3%) tumors recurred locally. Median time to local recurrence was not reached with a mean of 1,713 days. The estimated proportions of tumors that recurred locally at 1, 2, and 5 years were 17.3, 22.1, and 33.3%, respectively. Eleven (39.3%) dogs developed MCTs at other cutaneous locations. Median progression-free survival was 1,044 days. Median overall survival was 1,426 days. The combination of Ki-67 and PCNA scores was prognostic for local recurrence (P = .03) and development of local recurrence was prognostic for decreased overall survival (P = .04). Results suggest that a minority of incompletely excised MCTs recur. Therefore, ancillary local therapies may not always be necessary. However, local recurrence can negatively affect survival of the affected dogs. Cellular proliferation indices may indicate the likelihood of MCT recurrence after incomplete excision.

The medical records of 24 dogs with histologically confirmed mast cell tumors (MCT) of the muzzle were retrospectively evaluated to determine their biologic behavior and prognostic factors. Information on signalment, tumor grade and stage, treatment methods, and pattern of and time to failure and death was obtained from the medical record. Twenty-three dogs were treated with combinations of radiotherapy, surgery, and chemotherapy; 1 dog received no treatment. There were 2 Grade 1, 15 Grade 11, and 7 Grade III tumors. Tumors were stage 0 (n = 8), stage 1 (5), stage 2 (6), stage 3 (4), and stage 4 (1). Mean and median survival times of treated dogs were 36 and 30 months, respectively. Prognostic factors affecting survival time included tumor grade and presence of metastasis at diagnosis. Dogs with Grade I and II tumors survived longer than dogs with Grade III tumors. Variables, including sex, age, gross versus microscopic disease, and treatment type were not found to affect survival. Local control rate was 75% at 1 year and 50% at 3 years. Tumor grade was the only variable found to affect local control. Dogs with Grade I tumors had longer disease-free intervals than those with Grade II tumors, and dogs with Grade II tumors had longer disease-free intervals than dogs with Grade III tumors. Eight of 9 dogs dying of MCT had local or regional disease progression. Muzzle MCT a rebiologically aggressive tumors with higher regional metastatic rates than previously reported for MCT in other sites.

Thirty-five dogs with 37 soft tissue sarcoma tumors that were incompletely excised and treated with radiotherapy in the postoperative, adjuvant setting were reviewed. Variables evaluated included age, sex, tumor site, tumor histology, total tumor radiation dose, radiotherapy field size. time to recurrence, and survival. The majority of tumors were fibrosarcomas and hemangiopericytomas, but small numbers of other tumor types were also represented. Total tumor radiation dose ranged from 42 to 57 Gy given in 3- to 4.2-Gy daily fractions on a Monday through Friday schedule. Overall median survival was 1,851 days. Median time to local recurrence was greater than 798 days. Soft-tissue sarcoma tumors at oral sites had a statistically significant lower median survival (540 days) as compared to other tumor sites (2,270 days). Radiotherapy may be a useful adjuvant therapy for incompletely excised soft-tissue sarcomas with a reasonable expectation for long-term patient survival.

A retrospective study was conducted between two groups of dogs with histopathologically diagnosed multicentric malignant lymphoma to determine if treatment with either short-term or continuous chemotherapy resulted in a significant difference in first-remission length or survival time. One group was treated with single agent, short-term (three cycles) of doxorubicin. Dogs obtaining complete remission while receiving doxorubicin were given no further chemotherapy. The other group received combination agent, long-term chemotherapy consisting of cyclophosphamide, vincristine sulfate, and prednisone (COP). Dogs obtaining complete remission on COP by the end of 6 weeks were given maintenance chemotherapy of cyclophosphamide, prednisone and methotrexate. One hundred and five dogs were treated. Thirty-eight dogs received doxorubicin and 67 received COP. All dogs were evaluated at 6 weeks for response to chemotherapy and followed until death. No significant differences were observed in first-remission length or survival time when comparing dogs treated with either short-term doxorubicin or long-term COP (P greater than 0.05). Sex, weight, age, clinical stage, performance status, histopathologic cell type, and grade were not significant factors for determining the responsiveness to either chemotherapy protocol. However, within either treatment group, significant differences in first-remission length were observed in dogs evaluated histopathologically by the Keil and NCI working formulation and in survival time when evaluated by performance status (P less than 0.05).

Fifteen dogs with relapsed lymphoma were treated with doxorubicin and dacarbazine (ADIC) to reinduce remission. All the dogs' lymphomas had become resistant to prior therapy with doxorubicin alone. Five of the 15 dogs had a complete response to the first treatment with ADIC, and three had partial responses. Of the eight dogs receiving a second cycle, two had complete responses, and one had a partial response. One dog that received a third ADIC treatment no longer responded. The median survival time from the first ADIC treatment for all dogs was 45 days (range, 18-241 days). The five dogs having complete responses to the first ADIC treatment had a median survival time of 105 days (range, 45-241 days) after this treatment. Toxicity due to ADIC treatment was acceptable and did not exceed that seen when doxorubicin was given as a single agent. The treatment resulted in severe neutropenia in three dogs. One dog died due to neutropenic sepsis. Vomiting, diarrhea, and anorexia occurred, but were tolerable, resulting in hospitalization in only one instance. ADIC is apparently a useful chemotherapeutic combination to reinduce remission in some dogs with relapsed lymphoma.