Inductively coupled plasma mass‐spectrometric determination of platinum in excretion products of client‐owned pet dogs

Residues of antineoplastic drugs in canine excretion products may represent exposure risks to veterinary personnel, owners of pet dogs and other animal care‐takers. The aim of this study was to measure the extent and duration of platinum (Pt) excretion in pet dogs treated with carboplatin. Samples were collected before and up to 21 days after administration of carboplatin. We used validated, ultra‐sensitive, inductively coupled plasma‐mass spectrometry assays to measure Pt in canine urine, faeces, saliva, sebum and cerumen. Results showed that urine is the major route of elimination of Pt in dogs. In addition, excretion occurs via faeces and saliva, with the highest amounts eliminated during the first 5 days. The amount of excreted Pt decreased over time but was still quantifiable at 21 days after administration of carboplatin. In conclusion, increased Pt levels were found in all measured excretion products up to 21 days after administration of carboplatin to pet dogs, with urine as the main route of excretion. These findings may be used to further adapt current veterinary guidelines on safe handling of antineoplastic drugs and treated animals.     

Quality of life assessment in dogs and cats receiving chemotherapy – a review of current methods

This study aimed to review currently reported methods of assessing the effects of chemotherapy on the quality of life (QoL) of canine and feline patients and to explore novel ways to assess QoL in such patients in the light of the experience to date in human pediatric oncology. A qualitative comparative analysis of published papers on the effects of chemotherapy on QoL in dogs and cats were conducted. This was supplemented with a comparison of the parameters and domains used in veterinary QoL‐assessments with those used in the Pediatric Quality of Life Inventory (PedsQL^?) questionnaire designed to assess QoL in toddlers. Each of the identified publications including QoL‐assessment in dogs and cats receiving chemotherapy applied a different method of QoL‐assessment. In addition, the veterinary QoL‐assessments were mainly focused on physical clinical parameters, whereas the emotional (6/11), social (4/11) and role (4/11) domains were less represented. QoL‐assessment of cats and dogs receiving chemotherapy is in its infancy. The most commonly reported method to assess QoL was questionnaire based and mostly included physical and clinical parameters. Standardizing and including a complete range of potentially relevant parameters in future QoL assessments may benefit owner decision making.     

Phase II open‐label study of single‐agent hydroxyurea for treatment of mast cell tumours in dogs*

This prospective study evaluated the efficacy and safety of hydroxyurea (HU) in dogs with measurable mast cell tumours (MCTs). Dogs were treated with HU at 60 mg kg^?1per os q24h for 14 days then 30 mg kg^?1 q24h thereafter or until MCT recurrence. Forty‐six dogs were enrolled. The overall response rate was 28%. Two dogs had a complete response (CR) for 256 and 448 days, respectively. Eleven dogs had a partial response for a median duration of 46 days (range, 28–189 days). Grade 2 to 4 neutropenia occurred in eight dogs and grade 4 thrombocytopenia in two. Grade 3–4 anaemia occurred in seven dogs; overall, there was a significant decrease in haematocrit after treatment with HU. The median drop in haematocrit was 10%. This study demonstrated that HU has activity in the treatment of MCTs with mild anaemia being the primary adverse event.     

A phase II study to evaluate the toxicity and efficacy of alternating CCNU and high‐dose vinblastine and prednisone (CVP) for treatment of dogs with high‐grade,metastatic or nonresectable mast cell tumours

Safety and efficacy of a protocol of alternating 1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea (CCNU; 70 mg m^?2) and vinblastine (3.5 mg m^?2), and prednisone (1–2 mg kg^?1; CVP) in dogs with mast cell tumours (MCT) were evaluated. A total of 17 dogs had nonresectable MCTs and 35 received CVP as adjunctive treatment to locoregional control of metastatic MCTs or grade III MCTs. Neutropenia with fever occurred in 8% of dogs after treatment with vinblastine and in 2% after treatment with CCNU. Persistent elevation of serum alanine transaminase, suggestive of hepatotoxicity, occurred in 9% of the dogs. Response rate in dogs with nonresectable MCTs was 65%; five achieved a complete response (median, 141 days) and six achieved a partial response (median, 66 days). Overall median progression‐free survival (PFS) time in dogs treated in the adjuvant setting was 489 days. Dogs with grade III MCTs had shorter PFS compared with dogs with metastatic grade II MCTs (190 days versus 954 days; P < 0.001). Phase III studies are needed to provide reliable information about the comparative efficacy of this protocol.     

Determination of platinum surface contamination in veterinary and human oncology centres using inductively coupled plasma mass spectrometry

The objective of this study was to determine the surface contamination with platinum‐containing antineoplastic drugs in veterinary and human oncology centres. Inductively coupled plasma mass spectrometry was used to measure platinum levels in surface samples. In veterinary and human oncology centres, 46.3 and 68.9% of the sampled surfaces demonstrated platinum contamination, respectively. Highest platinum levels were found in the preparation rooms (44.6 pg cm^?2) in veterinary centres, while maximal levels in human centres were found in oncology patient‐only toilets (725 pg cm^?2). Transference of platinum by workers outside areas where antineoplastic drugs were handled was observed in veterinary and human oncology centres. In conclusion, only low levels of platinum contamination attributable to carboplatin were found in the sampled veterinary oncology centres. However, dispersion of platinum outside areas where antineoplastic drugs were handled was detected in veterinary and human oncology centres. Consequently, not only personnel, but also others may be exposed to platinum.     

A multi-centre prospective evaluation of internet research habits among owners seeing a veterinary oncologist

The purpose of this study is to evaluate the internet-use among pet owners seeing a veterinary oncologist. Over a two-month period, 137 questionnaires were collected at three specialty hospitals around a large urban city. Approximately 85% of respondents reported using the internet to research their pet's condition and/or treatment. A search engine was the most employed means however veterinary university websites were considered to provide the most accurate information. The odds of owners who researched their own health condition online researching their pet's condition was 4.3 (95% CI: 1.2–23.1, p < .021) times as high as owners who did not research their own health condition. The odds of owners who have been to their oncologist previously to research their pet's condition was 4.7 (95% CI: 26.9.3, p < .001) times as high than owners who have not been to an oncologist previously. Oncologists should be aware internet use among pet owners appears common and further research to assess the accuracy and readability of veterinary medical websites appears indicated.     

Extravasation reactions associated with the administration of pamidronate: 11 cases (2008–2013)

Pamidronate is a bisphosphonate drug widely utilized in veterinary oncologic practice for the palliation of malignant osteolysis. Pamidronate has not been previously reported to cause tissue injury upon extravasation in dogs. The medical records of 11 client‐owned dogs undergoing palliative treatment for primary bone tumors with known or suspected pamidronate extravasation reactions were reviewed. The majority of adverse events were low grade in nature, however in some cases, the reactions were severe and led to euthanasia in one instance. Time to complete resolution of lesions ranged from within several days to greater than one and a half months. Aside from the dog that was euthanized, no long‐term sequelae of extravasation were identified. Treatments employed to address the reactions varied widely. Pamidronate extravasation reaction appears to be an uncommon, but potentially serious complication of intravenous administration.     

Risk factors for development of sterile haemorrhagic cystitis in canine lymphoma patients receiving oral cyclophosphamide: a case–control study

Sterile haemorrhagic cystitis (SHC) is a known risk of cyclophosphamide treatment; however, most canine reports are case series. This case–control study examined risk factors for SHC in dogs with lymphoma receiving oral cyclophosphamide. Twenty‐two dogs with SHC and 66 control dogs were identified. On univariate analysis, SHC risk factors included age (P = 0.041), induction protocol (P = 0.021) and cumulative cyclophosphamide dose (P = 0.002). On multivariate analysis, increasing cumulative cyclophosphamide dose was associated with increased risk of SHC and the ‘short’ induction protocol (protocol 1) was associated with decreased risk. Controlling for age and induction protocol, odds of SHC increased by 2.21 per 750 mg m^?2 increase in cyclophosphamide dose (P = 0.001). SHC from oral cyclophosphamide is a predominately delayed toxicity resulting from high cumulative doses.     

Phase II clinical evaluation of lomustine chemotherapy for feline vaccine‐associated sarcoma

Treatment of feline vaccine‐associated sarcoma (VAS) is challenging, in part due to the high likelihood of tumour recurrence despite aggressive local therapy. Lomustine is potentially an attractive agent to add to the current treatment armamentarium. In this de‐escalating phase I/II prospective trial, 28 cats with measurable VAS were treated at target dosages of 38–60 mg m^?2 every 3 weeks until disease progression. The overall response rate was 25%, with a median progression‐free survival and median duration of response of 60.5 and 82.5 days, respectively. Haematologic toxicity, specifically cumulative neutropenia, was significant, and dose reductions and treatment delays were common. Although these data support further investigation of lomustine for the treatment of VAS, safe, multidosing protocols must first be determined.     

A retrospective analysis of the efficacy of Oncept vaccine for the adjunct treatment of canine oral malignant melanoma

Oral malignant melanoma (OMM) in the dog is often locally aggressive with a high metastatic potential and there are few treatment options that have been demonstrated to improve outcome of this disease. The purpose of this study was to determine whether adjunctive treatment with the Oncept melanoma vaccine affected the outcome of dogs with OMM that had achieved loco‐regional cancer control. Medical records from 45 dogs that presented to the Animal Cancer and Imaging Center were reviewed, including 30 dogs with stage II and III disease. Dogs that received the vaccine did not achieve a greater progression‐free survival, disease‐free interval or median survival time than dogs that did not receive the vaccine.     

Comparison between L-CHOP and an L-CHOP protocol with interposed treatments of CCNU and MOPP (L-CHOP-CCNU-MOPP) for lymphoma in dogs

An L-CHOP protocol with interposed treatments of CCNU and MOPP (L-CHOP-CCNU-MOPP) was evaluated in 66 dogs with stages III-V lymphoma. Results were compared with a historical group of 71 dogs treated with an L-CHOP protocol. Complete remission (CR) rates (85 and 80%, respectively) did not differ significantly between protocols (P = 0.48). First CR duration for dogs treated with L-CHOP-CCNU-MOPP was significantly longer: median, 317 days; 2-year CR rate, 35% versus median, 298 days; 2-year CR rate, 13%, P = 0.05). For the L-CHOP-CCNU-MOPP protocol, dogs in substage-b had a 4.3 times greater hazard of having a relapse than dogs in substage-a (P = 0.002). Frequency of adverse chemotherapy-associated gastrointestinal effects did not differ between protocols (P = 0.77). Neutropenia (primarily after CCNU) occurred more frequently in dogs treated with L-CHOP-CCNU-MOPP (P < 0.001). In summary, the L-CHOP-CCNU-MOPP protocol showed an improved duration of first CR as compared with an L-CHOP protocol, but the relevance of this finding might be subject to clinical judgement.     

Use of CD9 and CD61 for the characterization of AML‐M7 by flow cytometry in a dog*

Acute megakaryoblastic leukaemia (AML‐M7) is a rare myeloproliferative disorder in domestic animals. Recently, thanks to the greater availability of immunophenotype techniques, precise diagnosis is more easily made. The morphological evaluation has its limitations, especially in the study of poorly differentiated cells. Few reports have described AML‐M7 in dogs using flow cytometry. This clinical case points out the utility of flow cytometry in the characterization of AML‐M7 in a 3‐year‐old German Shepherd dog. Flow cytometry investigation has established megakaryocytic lineage involvement by showing the presence of two megakaryocyte/platelet associated antigens (CD9 and CD61). In human medicine CD9 may be used as a platelet and megakaryocyte marker. There is an evidence of cross‐reactivity of human anti‐CD9 monoclonal antibody with canine samples. To our knowledge, the use of CD9 has never been described before, for this purpose in the dog.     

Inter‐ and intra‐rater reliability and agreement in determining subcutaneous tumour margins in dogs

The objective of this prospective study was to evaluate agreement and reliability of calliper‐based measurements of locally invasive subcutaneous malignant tumours in dogs. Four raters measured the longest diameter of 12 subcutaneous tumours (7 soft tissue sarcomas and 5 mast cell tumours) from 11 client‐owned dogs during 3 randomized, blinded measurement trials, both pre‐ and post‐sedation. Inter‐ and intra‐rater reliability was evaluated using intra‐class correlation coefficient (ICC) and agreement was evaluated using Bland‐Altman plots. Inter‐ and intra‐rater reliability was good (ICC range of 0.8694‐0.89520) and excellent (ICC range of 0.9720‐0.9966), respectively. For agreement calculations, an a priori clinically relevant limit of agreement of 10 mm was set. Inter‐ and intra‐rater agreement was unacceptable with inter‐rater limits of agreement ranging from 15.9 to 55.6 mm and intra‐rater limit of agreement ranging from 11.9 to 28.1 mm. Review of the measurement trial photographs revealed that calliper orientation changes were frequent, occurring in 9/12 (75%) and 8/12 (67%) pre‐ and post‐sedation cases. No significant correlation was found between inter‐rater measurement standard deviations and calliper orientation changes or dog body condition score. These findings suggest veterinarians may have poor agreement in determining the gross edge of tumours, which is expected to introduce bias and inconsistency in tumour staging, assessing response to therapy, and surgical margin planning. Due to the potential consequences for veterinary cancer patients, future studies are needed to validate the present findings.     

Indirect assessment of dihydropyrimidine dehydrogenase activity in cats

Use of 5‐fluoropyridimine antimetabolite drugs, specifically 5‐fluorouracil (5‐FU), has been discouraged in cats because of adverse events including neurotoxicity and death. Causes of toxicity have never been elucidated. In humans, toxicity has been associated with ineffective metabolism secondary to deficiencies in dihydropyrimidine dehydrogenase (DPD). Direct assessment of DPD activity is challenging; determination of uracil:dihydrouracil (U:UH₂) in plasma using high performance liquid chromatography (HPLC) has been reported as an indirect measurement. U:UH₂ was measured in the plasma of 73 cats. Mean U:UH₂ for all cats was 1.66 ± 0.11 (median 1.53, range 0.24–7.00). Seventeen (23%) cats had U:UH₂ >2, a value associated with decreased DPD activity in humans. Spayed female cats had significantly lower U:UH₂ as compared with intact females, and age and U:UH₂ were weakly but significantly negatively correlated (r = ?0.26). Studies correlating U:UH₂ and 5‐FU tolerability are required to further determine the validity and use of this test in cats.     

Novel acyclic nucleotide analogues GS‐343074 and GS‐424044 demonstrate antiproliferative and pro‐apoptotic activity in canine neoplastic cell lines

GS‐9219, a novel prodrug of the nucleotide analogue 9‐(2‐phosphonylmethoxyethyl) guanine (PMEG) has significant activity as monotherapy in dogs with non‐Hodgkin's lymphoma. Phase I trials have been initiated in humans based on the encouraging activity observed in canine lymphoma. Two new analogues of GS‐9219 (GS‐343074 and GS‐424044) were recently produced for evaluation as potential novel antineoplastic agents against solid tumours. As a preclinical step, effect of GS‐343074 and GS‐424044 were evaluated against ten canine cancer cell lines for antiproliferative effect. Both analogues displayed antiproliferative activity against multiple canine cancer cell lines, although GS‐343074 was more potent and of broader spectrum compared to GS‐424044. Flow cytometric analysis of cells that experienced growth inhibition support apoptotic death as a mechanism of action for both analogues. On the basis of in vitro results described here, GS‐343074 and GS‐424044 show promise as novel anticancer agents in canine cancer.     

Liposome‐encapsulated chemotherapy: Current evidence for its use in companion animals

Cytotoxic drugs encapsulated into liposomes were originally designed to increase the anticancer response, while minimizing off‐target adverse effects. The first liposomal chemotherapeutic drug was approved for use in humans more than 20 years ago, and the first publication regarding its use in a canine cancer patient was published shortly thereafter. Regardless, no general application for liposomal cytotoxic drugs has been established in veterinary oncology till now. Due to the popularity of canines as experimental models for pharmacokinetic analyses and toxicity studies, multiple publications exist describing various liposomal drugs in healthy dogs. Also, some evidence for its use in veterinary cancer patients exists, especially in canine lymphoma, canine splenic hemangiosarcoma and feline soft tissue sarcoma, however, the results have not been overwhelming. Reasons for this may be related to inherent issues with the enhanced permeability and retention effect, the tumour phenomenon which liposomal drugs exploit. This effect seems very heterogeneously distributed in the tumour. Also, it is potentially not as ubiquitously occurring as once thought, and it may prove important to select patients for liposomal therapy on an individual, non‐histology‐oriented, basis. Concurrently, new developments with active‐release modified liposomes in experimental models and humans will likely be relevant for veterinary patients as well, and holds the potential to improve the therapeutic response. It, however, does not resolve the other challenges that liposomal chemotherapy faces, and more work still needs to be done to determine which veterinary patients may benefit the most from liposomal chemotherapy.     

Phase I lead‐in and subsequent randomized trial assessing safety and modulation of regulatory T cell numbers following a maximally tolerated dose doxorubicin and metronomic dose cyclophosphamide combination chemotherapy protocol in tumour‐bearing dogs

Maximally tolerated dose (MTD) and metronomic dose chemotherapeutic approaches alter the immune system and the angiogenic process in different yet potentially complementary ways. A combination of MTD doxorubicin (MTD‐DOX) and metronomic cyclophosphamide (mCTX) protocol was evaluated for safety and effect on circulating regulatory T (Treg) cells. We found that mCTX can be safely administered with MTD‐DOX in tumour‐bearing dogs. Both combination DOX/mCTX and single‐agent DOX resulted in significant depletions of circulating lymphocytes throughout the chemotherapy cycle without apparent selectivity for Tregs. The indiscriminant lymphocyte depletions were similar between dogs randomized to receive DOX and dogs randomized to receive DOX/mCTX, suggesting this effect is because of DOX alone. These findings may have implications as to the therapeutic benefit (or lack thereof) of concurrent combination MTD and metronomic protocols. Future investigations are required to determine the effects and indeed the efficacy of concurrent versus sequential applications of MTD and metronomic chemotherapy protocols.     

Retrospective comparison of three doses of metronomic chlorambucil for tolerability and efficacy in dogs with spontaneous cancer

The study hypothesis is that higher doses of metronomic (low‐dose) chlorambucil will improve outcome without significantly worsening adverse events (AE). Retrospectively, 88 dogs were screened to assess for tolerability and response to chlorambucil utilizing retrospective and prospective data sets, comparing metronomic oral daily doses 4, 6 and 8 mg m². There were 78 and 70 dogs in the tolerability and efficacy portions, respectively. The severity of gastrointestinal (GI) AE was significantly worse, and time to development of GI events was significantly shorter at 6 mg m² than at 4 mg m² (both P < 0.001). Chlorambucil was discontinued earlier in the dogs treated at the 6 mg m² doses than in the dogs treated at 4 mg m² (P = 0.015). Thrombocytopenia occurred significantly earlier at 8 mg m² than at 4 mg m² (P = 0.017). Higher doses of metronomic (low‐dose) chlorambucil did not provide improved responses and were associated with more AE.     

Comparison of two questionnaires to assess gastrointestinal toxicity in dogs and cats treated with chemotherapy*

Questionnaires completed by pet owners are widely used instruments to monitor adverse gastrointestinal (GI) effects in the owners' animals undergoing chemotherapy and for reporting toxicoses in clinical trials; however, no questionnaires have been formally evaluated. This study compares two questionnaire-based evaluations of adverse GI events: a basic, open-ended questionnaire and a detailed questionnaire modelled after the grading in the Veterinary Co-operative Oncology Group-Common Terminology Criteria for Adverse Events (VCOG-CTCAE). Owners completed both questionnaires after their dog or cat received moderately emetogenic chemotherapy. Results were used to derive toxicity grades for anorexia, vomiting and diarrhoea. We evaluated 123 pairs of questionnaires. Disagreement in grade of anorexia, vomiting and diarrhoea was found in 24, 7 and 13% of paired questionnaires, respectively (κ = 0.63, 0.83 and 0.71, respectively). Although 'good' to 'very good' agreement was found, the potential for only 'fair' agreement between questionnaire methods is of concern and suggests a need to adopt a standardized form.     

Evaluation of optimal water fluoridation on the incidence and skeletal distribution of naturally arising osteosarcoma in pet dogs

Experimental toxicological studies in laboratory animals and epidemiological human studies have reported a possible association between water fluoridation and osteosarcoma (OSA). To further explore this possibility, a case‐control study of individual dogs evaluated by the UC Davis Veterinary Medical Teaching Hospital was conducted using ecologic data on water fluoridation based on the owner's residence. The case group included 161 dogs with OSA diagnosed between 2008–2012. Two cancer control groups included dogs diagnosed with lymphoma (LSA) or hemangiosarcoma (HSA) during the same period (n = 134 and n = 145, respectively). Dogs with OSA were not significantly more likely to live in an area with optimized fluoride in the water than dogs with LSA or HSA. Additional analyses within OSA patients also revealed no significant differences in age, or skeletal distribution of OSA cases relative to fluoride status. Taken together, these analyses do not support the hypothesis that optimal fluoridation of drinking water contributes to naturally occurring OSA in dogs.