Changes in Regulatory T Cells in Dogs with Cancer and Associations with Tumor Type

Background: Regulatory T cells (Treg) have been shown to suppress antitumor immunity and often are increased in humans and rodents with cancer. However, Tregs have not been well studied in dogs with cancer and it is not known if certain tumor types are associated with increased Tregs.
Hypothesis: We hypothesized that Treg percentages would be increased in dogs with cancer and that Treg percentages would be higher in dogs with certain types of cancer.
Animals: The percentages and numbers of Tregs and nonregulatory T cells and B cells were assessed in 34 dogs with cancer and 9 age-matched control dogs. Dogs evaluated included 14 dogs with sarcoma, 7 dogs with carcinoma, 7 dogs with lymphoma, and 6 dogs with mast cell tumor.
Methods: Numbers and percentages of Tregs, CD4⁺, and CD8⁺ T cells and B cells were determined using flow cytometry and compared between control dogs and dogs with cancer.
Results: The percentage of Tregs was significantly increased overall in dogs with cancer compared with control dogs. When tumor types were compared, Treg percentages were significantly increased in dogs with carcinoma. The Treg/CD8 T cell ratio was significantly higher in dogs with cancer compared with control dogs and was also significantly increased in 2 dogs with T-cell lymphoma.
Conclusions: Treg percentages in blood were increased in dogs with cancer, particularly in dogs with carcinoma. The Treg/CD8 ratio also identified tumor-specific abnormalities in dogs with cancer. These findings indicate that tumor-specific factors may affect Tregs in dogs.     

Decreased Ratio of CD8+ T Cells to Regulatory T Cells Associated with Decreased Survival in Dogs with Osteosarcoma

Background: Increased numbers of regulatory T cells (Treg) and decreased ratios of CD8+ T cells to Treg have been shown to correlate with decreased survival times (ST) in humans with certain malignancies. A possible connection between Treg and ST in dogs with cancer has not been investigated previously. Hypothesis: The purpose of this study was to compare numbers of Treg and T lymphocyte subsets in dogs with osteosarcoma (OSA) to those of healthy dogs and to determine whether pretreatment values were associated with disease‐free interval or with ST. We hypothesized that Treg numbers would be increased in dogs with cancer and that dogs with a high percentage of Treg would have a poorer prognosis. Animals: Twelve client‐owned dogs with appendicular OSA were entered into a prospective clinical trial. Twenty‐two healthy dogs were used as controls. Methods: The percentages and numbers of Treg and CD4+ and CD8+ T cells in blood, lymph nodes, and tumors were determined with flow cytometry and compared between dogs with OSA and control dogs. Results: Dogs with OSA had significantly fewer circulating CD8+ T cells and significantly more Treg compared with healthy dogs. The CD8/Treg ratio also was significantly lower in dogs with OSA compared with control dogs. In dogs with OSA, a decreased CD8/Treg ratio was associated with significantly shorter STs. Conclusions: These data support a role for Treg in the immune control of canine OSA and suggest that determination of the CD8/Treg ratio may be useful for assessing outcomes.     

调节性T细胞与肿瘤研究进展

调节性T细胞是机体内存在的一群具有免疫抑制性作用的细胞,对于维护机体免疫平衡具有重要作用,同时其与肿瘤的发生发展关系密切。关于调节性T细胞的研究很多,但其在体内如何调控肿瘤的发生发展仍不清楚。随着对调节性T细胞的表型以及其作用机制的深入研究,发现调节性T细胞可能在不同类型的肿瘤内对疾病起到完全相反的作用。同时通过其作用机制的研究,也筛选出了一批肿瘤免疫治疗的潜在靶点,为肿瘤免疫治疗领域,如单克隆抗体和小分子抑制剂开发等提供了新思路。     

Intracavitary Cisplatin Chemotherapy Experience with Six Dogs

Six dogs with a median age of 7 years (range = 5-14 years) were presented for signs referable to thoracic or abdominal effusion associated with neoplasia of the body cavities. Intracavitary cisplatin was administered at 50 mg/m2 every 4 weeks for a median of 2.5 treatments (mean = 3, range = 1-6). Three dogs with pleural mesothelioma had complete resolution of effusion for 289, 129, and greater than 306 days without evidence of tumor growth. Resolution of effusion occurred after one treatment in two dogs and after two treatments in one dog. In three dogs with carcinomatosis of unknown origin, complete responses was seen in two dogs after one treatment for 255 and greater than 807 days, respectively. Intracavitary chemotherapy with cisplatin was associated with palliation and control of malignant pleural and/or abdominal effusion in five of six dogs. Toxicity was minimal, and this method of therapy should be further explored in dogs with similar malignancies.     

调节性T细胞及在结核分支杆菌感染中的作用研究进展

结核病是由结核分支杆菌引起的慢性消耗性传染病。结核分支杆菌属于胞内寄生菌,机体的抗结核免疫主要依赖特异性的细胞免疫。调节性 T 细胞（Treg）是一类具有免疫抑制功能的 T 细胞亚群,在结核病的发生发展过程中起重要作用,Treg 在抗结核免疫中的作用成为研究热点。论文就调节性 T 细胞在结核分支杆菌感染中作用的研究进展做一综述。     

Hemodynamic and Biochemical Alterations in Dogs with Lymphoma after Induction of Chemotherapy

Background

Doxorubicin is a common antineoplastic agent with dose‐dependent cardiotoxic adverse effects, and pre‐existing myocardial dysfunction is a contraindication to its use.

Objectives

To systematically define the hemodynamic and biochemical alterations in dogs undergoing chemotherapy for newly diagnosed lymphoma and assess the reversibility of these alterations with fluid administration.

Animals

Twenty‐one client‐owned dogs with newly diagnosed lymphoma were evaluated 1 week after induction of chemotherapy. Underlying degenerative valve disease was exclusionary. Eighteen healthy age‐ and weight‐matched dogs were used as controls.

Methods

Physical examination, blood pressure by Doppler, echocardiography, and biochemical evaluation (routine serum biochemistry, plasma renin activity and aldosterone concentrations, plasma and urine osmolalities, and urine electrolyte concentrations) were measured in dogs with lymphoma and compared to controls. Dogs with lymphoma received crystalloids IV at 6 mL/kg/h for 24 hours. All variables were reassessed at 4 and 24 hours. Deuterium oxide dilution and bromide dilution were used to determine total body water and extracellular water space, respectively.

Results

Baseline echocardiograms showed significantly smaller chamber dimensions in dogs with lymphoma compared to controls. These changes were reversed by fluid administration. Systolic blood pressure and urine sodium concentration were significantly increased, and bromide dilution space, PCV, urine specific gravity, and urine potassium concentration were significantly decreased compared to controls.

Conclusion and Clinical Importance

Echocardiographic and biochemical abnormalities in dogs with lymphoma appear consistent with volume depletion, and may be the result of systemic hypertension and subsequent pressure natriuresis.     

A Combination Chemotherapy Protocol (VELCAP-L) for Dogs with Lymphoma

Ninety-eight dogs with lymphoma treated with a 5-drug combination chemotherapy regimen (vincristine, L-asparaginase. cyclophosphamide, doxorubicin, prednisone [VELCAP-L]) were evaluated for pretreatment characteristics predictive for response and remission duration. The complete remission rate was 69%, with a median remission duration of 55 weeks. Dogs with advanced stage of disease, constitutional signs, dogs that were older, and dogs that were dyspneic were less likely to achieve remission. Once in remission, small dogs and dogs without pretreatment thrombocytopenia were likely to have longer remission duration. Toxicoses were frequent, but rarely fatal, and no predictitive factors were found for a dog developing toxicoses. VELCAP-L is an effective treatment for dogs in stage I-III lymphoma, particularly in young, small animals.     

Drug Residues in Serum of Dogs Receiving Anticancer Chemotherapy

Background: The presence of drug residues in blood samples can represent an occupational hazard. However, studies on cytotoxic drug residues in serum of dogs are lacking in veterinary oncology. Objective: To evaluate possible occupational hazards associated with handling of blood samples from dogs receiving oncolytic drugs 7 days after treatment. Animals: Twenty‐seven client‐owned dogs treated for lymphoma or mast cell tumors with vincristine, vinblastine, cyclophosphamide, or doxorubicin. Methods: Prospective, observational study. Serum samples were either taken 7 days after administration of vincristine, cyclophosphamide, doxorubicin (lymphoma), and vinblastine (mast cell tumor), or 1–2 days after the last concurrent oral administration of cyclophosphamide (mast cell tumor). Additionally, serum was collected within 5 minutes of treatment. Measurement of drug residues in serum was performed by liquid chromatography tandem mass spectrometry (LC/MS/MS). Results: In 33 samples collected within 5 minute of treatment, the median serum concentrations were vincristine: 37 μg/L (range: 11–87 μg/L), vinblastine: 13 μg/L (range: 13–35 μg/L), cyclophosphamide: 2,484 μg/L (range: 1,209–2,778 μg/L), doxorubicin: 404 μg/L (range: 234–528 μg/L). In 81 serum samples collected 7 days after treatment vinblastine (7 μg/L) was detected in 1 sample, and cyclophosphamide (7 and 9 μg/L) in 2 samples collected 1–2 days after oral administration of cyclophosphamide. Medications were not detected in any of the other samples. Conclusions and Clinical Importance: Handling of blood samples from dogs receiving oncolytic chemotherapy 7 days after treatment with vincristine, vinblastine, cyclophosphamide, and doxorubicin should not present a health hazard.     

Ventricular Arrhythmias in Dogs Undergoing Splenectomy: A Prospective Study

Fifty dogs undergoing splenectomy for splenic masses (n = 40), torsion of the splenic pedicle (n = 5), and immune-mediated disease (n = 5) were evaluated preoperatively and postoperatively for ventricular arrhythmias and the relationship between ventricular arrythmia and splenic disease. The ability of 1 -minute electrocardiograms recorded every 6 hours (ECGs/q6hr) to detect ventricular arrythmia was compared with continuous 48-hour Holter monitoring. Based on continuous Holter monitoring, splenectomized dogs had a high incidence (22 of 50) of rapid ventricular tachycardia. The incidence of rapid ventricular tachycardia was significantly higher in dogs with ruptured splenic masses (16 of 23) than without rupture (1 of 17) ( P < .001). When the results of ECG/q6hr were compared with the results of continuous Holter monitoring, ECG/q6hr was normal in 29% (4 of 14) of dogs with rapid ventricular tachycardia at > 3,000 ventricular extrasystoles (VE)/hr; 50% (4 of 8) of dogs with rapid ventricular tachycardia at 1,000 to 3,000 VE/hr and 100% (6 of 6) of dogs with 10 to 300 VE/hr without rapid ventricular tachycardia. Although dogs undergoing splenectomy had a high incidence of ventricular arrythmias, one-minute ECGs/q6h were unreliable for detection of ventricular arrythmias even when high-frequency extrasystoles occurred.     

Survey of Intraoperative Bacterial Contamination in Dogs Undergoing Elective Orthopedic Surgery

Objective

To investigate the frequency, source, and risk factors of intraoperative (IO) surgeon and patient bacterial contamination during clean orthopedic surgeries, and to investigate the relationship between IO contamination and surgical site infection (SSI) in dogs.

Study Design

Prospective clinical study.

Sample Population

Client‐owned dogs undergoing stifle surgery (n = 100).

Methods

IO cultures were taken in each case from surgical foot wrap, peri‐incisional skin, surgical gloves, and the surgical team's hands. The environment (operating room [OR] lights, computers, scrub sink faucet, anesthesia gurney, and radiology table) was sampled every 5 months. Bacteria were identified and the contamination of each case was categorized. All gloves from the surgical team were collected and tested for perforations using a water infusion test. Cases were followed for at least 8 weeks to determine the presence or absence of SSI. Perioperative variables were evaluated for association with IO contamination and SSI.

Results

Bacterial isolates were yielded from 81% of procedures from 1 or more sources; 58% had positive hand cultures, 46% had positive glove cultures, 23% had positive patient skin cultures, and 12% had positive foot wrap cultures. Staphylococcus spp. was the most commonly recovered bacteria. There was no apparent association between IO contamination and SSI. The highest level of environmental contamination was associated with the scrub sink faucet, followed by the radiology table, anesthesia gurney, and OR computers. The IO glove perforation rate was 18%.

Conclusion

Clean orthopedic procedures commonly had clinically insignificant bacterial contamination. In our study, bacteria responsible for SSI did not appear to colonize the patient in the OR.     

Cytotoxic Drug Residues in Urine of Dogs Receiving Anticancer Chemotherapy

The presence of cytotoxic drug residues in urine of dogs may represent an exposure risk for pet owners and other people as well as a potential environmental contaminant. However, studies on cytotoxic drug residues in excretions of clinical patients are lacking in veterinary oncology. Hypothesis: Variable concentrations of cytotoxic residues are present in urine samples, depending on sampling time and substance. Animals: Client‐owned dogs with lymphoma or mast cell tumors treated with standard chemotherapy protocols. Methods: Urine samples were collected before, directly after, and on days after administration of chemotherapy. Measurement of vincristine, vinblastine, cyclophosphamide, and doxorubicin residues in canine urine was performed by a quantitative liquid chromatography tandem mass spectrometry (LC/MS/MS) method. Results: Median cyclophosphamide residue concentration was 398.2 μg/L directly after treatment (d0) and was below the level of detection on days 1–3 (d1, d2, d3). Median vincristine residue concentration was 53.8 μg/L directly after treatment and was 20.2, 11.4, and 6.6 μg/L on days 1, 2, and 3. Median vinblastine residues were 144.9 (d0), 70.8 (d1), 35.6 (d2), and 18.7 μg/L (d3) with low concentrations detectable for 7 days after treatment. Median urine doxorubicin concentrations were 354.0 (d0), 165.6 (d1), 156.9 (d2), and 158.2 μg/L (d3). Low concentrations of doxorubicin were measurable up to 21 days after administration. Conclusions and Clinical Importance: Variable concentrations of chemotherapeutics were measured in urine samples, depending on sampling time point and drug. Findings may inform current chemoprotection guidelines and help minimize exposure risks.     

Adverse Effects of Concurrent Carboplatin Chemotherapy and Radiation Therapy in Dogs

Background: Concurrent chemo- and radiotherapy improves outcome of certain human neoplasms but with increased signs of toxicity. Reports on adverse effects of concurrent chemo- and radiotherapy in the veterinary literature are scant.
Objective: To report adverse hematologic and gastrointestinal effects of combined carboplatin and radiation therapy in dogs.
Animals: Client-owned dogs with spontaneously occurring neoplasia.
Methods: Retrospective case study. Medical records of 65 dogs were reviewed. Criteria for inclusion were administration of radiation according to 1 of 3 fractionation schemes (19 × 3, 16 × 3, or 12 × 4 Gy) and administration of at least 1 concurrent carboplatin treatment at a dosage of 200–300 mg/m². Dog and treatment-related variables were analyzed for association with signs of intoxication.
Results: Median carboplatin dosage was 200 mg/m² (range, 200–250 mg/m²). Twelve of 58 dogs (21%) developed grade 3 or 4 neutropenia. Eleven of 56 dogs (20%) developed grade 3 or 4 thrombocytopenia. Six of 62 dogs (10%) developed grade 3, 4, or 5 gastrointestinal toxicosis. Analysis of association of dog and treatment-related variables with signs of intoxication was hampered by the small numbers of dogs in individual groups, and no statistically significant associations were found.
Conclusions and Clinical Importance: Combined modality therapy resulted in myelosuppression and gastrointestinal toxicosis. Future studies are needed to determine whether the potential benefit of combined modality therapy outweighs the risk of decreasing chemotherapy and radiation treatment intensity.     

Efficacy of Combination Chemotherapy for Treatment of Gastrointestinal Lymphoma in Dogs

Background: Chemotherapy for multicentric canine lymphoma has favorable results. The gastrointestinal (GI) tract is the most common extranodal site of canine lymphoma, but there have been no prospective studies to determine outcome when dogs with GI lymphoma are treated with chemotherapy.
Hypothesis: Treatment with a multiagent chemotherapy protocol is associated with a poor outcome in dogs with GI lymphoma.
Animals: Eighteen dogs with histologically confirmed GI lymphoma.
Methods: Prospective clinical trial in which dogs with GI lymphoma were treated with a 20-week combination chemotherapy protocol consisting of induction and consolidation phases.
Results: Thirteen dogs had primary GI lymphoma and 5 had multicentric lymphoma with GI involvement. The majority of the lymphomas (63%) were of T-cell origin. Overall remission rate was 56%; 9 dogs achieved a complete remission for a median of 86 days (range, 22–420 days) and 1 dog achieved a partial remission for 26 days. Overall median survival time was 77 days (range, 6–700 days). Dogs that failed to achieve a remission (10 versus 117 days; P = .002) or had diarrhea at initial presentation (70 versus 700 days; P < .001) had shorter survival times.
Conclusion and Clinical Importance: The response and survival of dogs with GI lymphoma treated with multiagent chemotherapy is poor but long-term survival is possible.     

Comparison of Two Indwelling Central Venous Access Catheters in Dogs Undergoing Fractionated Radiotherapy

Twenty dogs with neoplasms requiring multiple radiation treatments received either percutaneous vascular access catheters (PVACs; Cook, Bloomington, IN) or subcutaneous vascular access ports (SVAPs; Vascular-Access-Ports, Norfolk Medical Products, Inc., Skokie, IL); 10 dogs were entered in each group. All catheters were implanted and removed aseptically and the catheter tips were cultured during implant removal. Complications with PVACs included mild incisional swelling and redness and accidental severance or rupture of the catheter. Complications with SVAPs included incisional or port swelling, bruising or redness, hematoma formation, and pain. Ports in 4 of these dogs could not be used for 1 to 3 days after surgery because of swelling and pain. Surgical wound complications, when pooled for comparison, occurred significantly more frequently with the SVAPs ( P = .023). Wound complications associated with both catheters were self-limiting and resolved within 7 days. Bacterial cultures were positive in two PVACs and four SVAP tips, however, none of these dogs had clinical signs of infection or sepsis. Although both types of indwelling catheters were functional in a clinical setting, PVACs were preferred to SVAPs for dogs undergoing radiation therapy because of decreased time for implantation and fewer overall complications.