SIOP pediatric oncology services Global Mapping Program: Latin American data collection

The International Society of Paediatric Oncology (SIOP) launched a program to map all pediatric cancer facilities around the world. After the results in Africa were completed, the strategy for data collection for Latin America was revised to improve the accuracy and avoid duplications. In partnership with SIOP, the Sociedad Latino Americana de Oncología Pediátrica (SLAOP) approached their delegates who provided the contacts for a 10-question survey about their institutional capacities. Data were collected by email, online meetings, or telephone calls, and stored in a secure platform. All but one country participated and a high number of centers were recorded.

Extracranial germ cell tumours: Mature and immature (1990-2015). First report by the South African Association of Paediatric Haematology Oncology (SAAPHO)

BACKGROUND AND OBJECTIVES

Outcomes of rare paediatric teratomas have not previously been reported nor treatment regimens standardised in low- and middle-income settings. We sought to evaluate treatment outcomes of children and adolescents with histologically confirmed extracranial germ cell tumours, both mature teratomas (MT) and immature teratomas (IT) in preparation for the development of the South African national treatment guideline.

METHODS

Retrospective data by folder review were collated from nine South African paediatric oncology units. Kaplan-Meier analysis with Cox regression was performed to determine 5-year overall survival (OS) and prognostic factors.

RESULTS

From January 1990 to December 2015, 60 patients were diagnosed with MTs; 14 males (median age 2 months; interquartile range [IQR]: 0-8.75 months) and 46 females (median age 9 months; IQR: 0-88.5 months). Forty patients were diagnosed with ITs; 10 males (median age less than 1 month; IQR: 0-1.75 months) and 30 females (median age 4.5 months; IQR: 1-162 months). There were high rates of upfront surgical resections in patients with MTs (58/60; 96.6%) and ITs (36/40; 90%), and similarly satisfactory rates of complete resection in patients with both MTs (55/60; 91.7%) and ITs (32/40; 80%). The 5-year OS for the whole group was 85.4%, significantly influenced by stage: Stage I (96.9%), Stage II (100%), Stage III (38.9%) (p < .001 [MT]; p = .013 [IT]). The event-free survival (EFS) ratio for the whole cohort was 78.7%.

CONCLUSIONS

Five-year OS for those with low-stage disease was excellent, but was poorer for patients with advanced disease. The implementation of a national treatment guideline will facilitate the standardising of surgical approaches, indications for chemotherapy and specifications for follow-up to improve survival and to collect more robust late effects data.

Improved survival of children and adolescents with classical Hodgkin lymphoma treated on a harmonised protocol in South Africa

BACKGROUND

Historic South African 5-year overall survival (OS) rates for Hodgkin lymphoma (HL) from 2000 to 2010 were 46% and 84% for human immunodeficiency virus (HIV)-positive and HIV-negative children, respectively. We investigated whether a harmonised treatment protocol using risk stratification and response-adapted therapy could increase the OS of childhood and adolescent HL.

METHODS

Seventeen units prospectively enrolled patients less than 18 years, newly diagnosed with classical HL onto a risk-stratified, response-adapted treatment protocol from July 2016 to December 2022. Low- and intermediate-risk patients received four and six courses of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD), respectively. High-risk patients received two courses of ABVD, followed by four courses of cyclophosphamide, vincristine, prednisone, and dacarbazine (COPDac). Those with a slow early response and bulky disease received consolidation radiotherapy. HIV-positive patients could receive granulocyte colony-stimulating factor and less intensive therapy if stratified as high risk, at the treating clinician's discretion. Kaplan-Meier survival analysis was performed to determine 2-year OS and Cox regression to elucidate prognostic factors.

RESULTS

The cohort comprised 132 patients (19 HIV-positive, 113 HIV-negative), median age of 9.7 years, with a median follow-up of 2.2 years. Risk grouping comprised nine (7%) low risk, 36 (27%) intermediate risk and 87 (66%) high risk, with 71 (54%) rapid early responders and 45 (34%) slow early responders, and 16 (12%) undocumented. Two-year OS was 100% for low-risk, 93% for intermediate-risk, and 91% for high-risk patients. OS for HIV-negative (93%) and HIV-positive (89%) patients were similar (p = .53). Absolute lymphocyte count greater than 0.6 × 109 predicted survival (94% vs. 83%, p = .02).

CONCLUSION

In the first South African harmonised HL treatment protocol, risk stratification correlated with prognosis. Two-year OS of HIV-positive and HIV-negative patients improved since 2010, partially ascribed to standardised treatment and increased supportive care. This improved survival strengthens the harmonisation movement and gives hope that South Africa will achieve the WHO Global Initiative for Childhood Cancer goals.

Socioeconomic status significantly impacts childhood cancer survival in South Africa

BACKGROUND AND AIMS

Significantly discrepant survival rates have been documented in single disease childhood cancer cohorts in South Africa; those from higher socioeconomic groups were shown to have a significantly lower risk of death than those from less affluent households. This study aimed to determine the impact of socioeconomic status (SES) on childhood cancer survival using pooled South African data.

METHODS

Five databases spanning January 2000 to December 2021 were interrogated. SES status was assigned based on a public sector annual household income classification. H0 households (formally unemployed) received free healthcare. H1, H2 and H3 (annual income > United States Dollar [USD] 19,000) households paid for healthcare relative to their income. The Spearman test assessed correlations between SES and disease stage in patients with solid tumours. Hazard ratios were determined using Cox regression modelling. The Kaplan-Meier procedure estimated overall survival (OS).

RESULTS

A total of 1598 children were eligible for analysis; 1269 had a solid tumour with a negative correlation between SES and stage (Spearman rho = -.178; p < .001). Patients with solid tumours and lower SES showed proportionately higher numbers of stage III and IV disease (p < .01). This proportion decreased with higher SES categories. In the multivariate analyses adjusted for sex, age, tumour type and stage, higher SES was associated with lower mortality risk (p < .001), indicating that the impact of SES on survival was in excess of any effect that could be explained by lower stage disease alone. There was a strong positive correlation between race and SES (Fisher's exact tests, p < .001) across all groups and all SES strata. Five-year OS was 85.3% in children from H3 households versus 46.3% in children from H0 households (p < .001).

CONCLUSION

SES significantly impacts childhood cancer survival for children with solid tumours in South Africa. SES is a robust surrogate for race in South Africa as a prognostic metric of disease outcome in childhood cancer. Advocacy to increase social support for impoverished patients is essential to achieve equitable improvements in outcomes treated with standardised national treatment guidelines.

Current status of African pediatric oncology education efforts aligned with the Global Initiative for Childhood Cancer

Education of the pediatric oncology workforce is an important pillar of the World Health Organization CureAll technical package. This is not only limited to healthcare workers, but all stakeholders in the childhood cancer management process. It includes governmental structures, academic institutions, parents and communities. This review evaluated the current educational and advocacy training resources available to the childhood cancer community, the contribution of SIOP Africa in the continental educational needs and evaluated future needs to improve the management of pediatric malignancies in reaching the Global Initiative for Childhood Cancer goals. Childhood cancer, unlike adult cancers, has not been prioritized in African cancer control plans nor the teaching and advocacy surrounding pediatric oncology. The availability of formal training programs for pediatric oncologists, pediatric surgeons and radiotherapy specialists are limited to particular countries. In pharmacy and nutritional services, the exposure to pediatric oncology is limited while training in advocacy doesn't exist. Many nonacademic stakeholders are creating the opportunities in Africa to gain experience and train in these various fields, but formal training programs should still be advocated for. LEARNING POINTSThe African continent has various resources to increase the capacity of childhood cancer care stakeholders to increase their knowledge.African pediatric oncology teams rely on a multitude of international sources for training while developing their own.There is a greater need for formal, standardized cancer training especially for pediatric surgeons, radio-oncologists and nurses.Greater inclusion of pathologists, pediatric oncology pharmacists and dieticians into multidisciplinary care and childhood cancer training should be facilitated and resourced.Successful advocacy programs and tool kits exist in parts of Africa, but the training in advocacy is still underdeveloped.

SACCSG HL-2018. Barriers and enablers of a harmonized treatment protocol for childhood and adolescent Hodgkin lymphoma in South Africa

Introduction: Collaborative studies have contributed to improved survival of pediatric Hodgkin lymphoma in well-resourced settings, but few are documented in resource-constrained countries. The South Africa Children's Cancer Study Group initiated harmonization of management protocols in 2015. This article analyzes barriers and enablers of the process. Methods: Clinician-researchers at 11 state-funded pediatric oncology units completed preparatory questionnaires in June 2018. Parameters included infrastructure, access to therapeutic modalities and clinician numbers. A reassessment of 13 sites (two new pediatric oncology unit) in February 2021 ascertained changes in resources and identified challenges to full participation. Questions investigated the presence and quality of diagnostic radiology, availability of surgeons, cytology/pathology options and hematology laboratory facilities. Results: The response rate was 11/11 to survey 1 and 13/13 to survey 2. The anticipated pre-study barriers to participation of pediatric oncology units included time constraints and understaffing. PET-CT was unavailable to two centers. The majority of pediatric oncology units met the minimum criteria to participate. The interim survey confirmed chemotherapy and radiotherapy availability nearly 100% of the time. One site reported improved access to radiotherapy while another reported improved access to PET-CT. Barriers to participation included excessive times to obtain regulatory approvals, time constraints and lack of dedicated research staff. Enablers include the simple management algorithm and communication tools. Conclusion: This study demonstrates that multicenter collaboration and harmonization of management protocols are achievable in a middle-income setting. Minimal funding is required but full participation to run high-quality studies requires more financial investment. Focused funding and increased prioritization of research may address systemic barriers to full participation.

Neuroblastoma survival in South African children is more influenced by biological than socioeconomic factors

Background: Optimal management of neuroblastoma depends on accurate risk stratification at diagnosis. Many low- and middle-income countries lack access to specific genetic tests used globally for this purpose.Aim: To determine whether socioeconomic factors predict prognosis in neuroblastoma and could therefore provide alternative measures for risk stratification in resource-constrained settings.Setting: The three main paediatric oncology units in Johannesburg, South Africa: Charlotte Maxeke Johannesburg Academic Hospital, Chris Hani Baragwanath Academic Hospital and Wits Donald Gordon Medical Centre.Methods: This retrospective record review included 145 patients presenting with biopsy-proven neuroblastoma between 01 January 2000 and 31 December 2018. Kaplan–Meier survival analysis was performed in relation to biological and socioeconomic factors, the latter including parental employment status, nationality, and distance of residence from treating facility. Cox proportional hazards regression analysis assessed the significance and effect of these prognostic factors.Results: Factors with significant effect on survival were age below 18 months (p  0.0001), extra-abdominal primary tumour site (p = 0.02), lower stage (p  0.001), serum ferritin level 0.0001) and favourable International Neuroblastoma Pathological Committee histology (p  0.0001), race (p = 0.005), nationality (p = 0.05) and paternal employment (p = 0.02). The association between distance from treating facility and stage at diagnosis was not significant (Tb = 0.108, p = 0.06).Conclusion: Biological factors exert a great influence on neuroblastoma survival than the socioeconomic factors analysed. This suggests that tumour biology exerts an overriding influence on prognosis in neuroblastoma. 

Conference report on the 14th International Society of Paediatric Oncology African Continental Meeting, 16–18 March 2022, Kampala, Uganda

Together with the Africa Continental Branch of the International Society of Paediatric Oncology (SIOP Africa), the Uganda Cancer Institute, a tertiary governmental institution for specialised cancer care services, research and training, hosted the 14th continental meeting of SIOP Africa from the 16–18 March 2022. Under the conference theme, ‘Innovate for Africa’, the hybrid conference brought together close to 400 international delegates to discuss innovations and experiences, as well as share the latest research in the field of paediatric oncology. The World Health Organisation 2030 Global Initiative for Childhood Cancer provided the main starting point for the conference with a comprehensive pre-conference workshop programme, from multiple stakeholders and organisations and the themes for the plenaries towards improving survival to the main breakout sessions. Delegates discussed various ways of improving outcomes in Africa, despite the challenges faced individually and collectively ranging from education, management systems and treatment guidelines to future governmental and NGO involvement in African cancer care. The main achievements of the conference were various commitments for collaboration, investing in junior investigators, development of registries and systems for improved childhood care on the African continent, while working towards greater access to advanced management options such as targeted therapies and bone marrow transplant services.

Cancer in sub-Saharan Africa: a Lancet Oncology Commission

In sub-Saharan Africa (SSA), urgent action is needed to curb a growing crisis in cancer incidence and mortality. Without rapid interventions, data estimates show a major increase in cancer mortality from 520 348 in 2020 to about 1 million deaths per year by 2030. Here, we detail the state of cancer in SSA, recommend key actions on the basis of analysis, and highlight case studies and successful models that can be emulated, adapted, or improved across the region to reduce the growing cancer crises. Recommended actions begin with the need to develop or update national cancer control plans in each country. Plans must include childhood cancer plans, managing comorbidities such as HIV and malnutrition, a reliable and predictable supply of medication, and the provision of psychosocial, supportive, and palliative care. Plans should also engage traditional, complementary, and alternative medical practices employed by more than 80% of SSA populations and pathways to reduce missed diagnoses and late referrals. More substantial investment is needed in developing cancer registries and cancer diagnostics for core cancer tests. We show that investments in, and increased adoption of, some approaches used during the COVID-19 pandemic, such as hypofractionated radiotherapy and telehealth, can substantially increase access to cancer care in Africa, accelerate cancer prevention and control efforts, increase survival, and save billions of US dollars over the next decade. The involvement of African First Ladies in cancer prevention efforts represents one practical approach that should be amplified across SSA. Moreover, investments in workforce training are crucial to prevent millions of avoidable deaths by 2030. We present a framework that can be used to strategically plan cancer research enhancement in SSA, with investments in research that can produce a return on investment and help drive policy and effective collaborations. Expansion of universal health coverage to incorporate cancer into essential benefits packages is also vital. Implementation of the recommended actions in this Commission will be crucial for reducing the growing cancer crises in SSA and achieving political commitments to the UN Sustainable Development Goals to reduce premature mortality from non-communicable diseases by a third by 2030.

Malignant extracranial germ cell tumours: A first national report by the South African Children's Cancer Study Group

OBJECTIVE

To determine the overall survival (OS) and prognostic factors influencing outcomes in children and adolescents with malignant extracranial germ cell tumours (MEGCTs) in preparation for the development of a harmonised national treatment protocol.

METHODS

A retrospective folder review was undertaken at nine South African paediatric oncology units to document patient profiles, tumour and treatment-related data and outcomes for all children with biopsy-proven MEGCTs from birth up to and including 16 years of age.

RESULTS

Between 1 January 2000 and 31 December 2015, 218 patients were diagnosed with MEGCTs. Female sex (hazard ratio [HR] 0.284, p = .037) and higher socio-economic status (SES) (HR 0.071, p = .039) were associated with a significantly lower risk of death. Advanced clinical stage at diagnosis significantly affected 5-year OS: stage I: 96%; stage II: 94.3%; stage III: 75.5% (p = .017) and stage IV (60.1%; p < .001). There was a significant association between earlier stage at presentation and higher SES (p = .03). Patients with a serum alpha-fetoprotein (AFP) level of more than 33,000 ng/ml at diagnosis had significantly poorer outcomes (p = .002). The use of chemotherapy significantly improved survival, irrespective of the regimen used (p < .001).

CONCLUSIONS

The cohort demonstrated a 5-year OS of 80.3% with an event-free survival (EFS) of 75.3%. Stage, the use of chemotherapy and an elevated serum AFP level of more than 33,000 ng/ml were independently predictive of outcome. The relationship between SES and outcome is important as the implementation of the new national protocol hopes to standardise care across the socio-economic divide.

Mapping Pediatric Oncology Clinical Trial Collaborative Groups on the Global Stage

The global pediatric oncology clinical research landscape, particularly in Central and South America, Africa, and Asia, which bear the highest burden of global childhood cancer cases, is less characterized in the literature. Review of how existing pediatric cancer clinical trial groups internationally have been formed and how their research goals have been pursued is critical for building global collaborative research and data-sharing efforts, in line with the WHO Global Initiative for Childhood Cancer.

Local stakeholder engagement is necessary to collaborate with global pediatric cancer trial groups.

Pediatric Oncology Clinical Trials and Collaborative Research in Africa: Current Landscape and Future Perspectives

PURPOSE

Adequate clinical services have yet to be established in the majority of African countries, where childhood cancer survival rates vary from 8.1% to 30.3%. The aim of this review is to describe the landscape of pediatric oncology trials in Africa, identify challenges, and offer future opportunities for research collaborations.

METHODS

The study includes data from the International Pediatric Oncology Society (SIOP) global mapping survey, meta-research identifying trials in Africa in ClinicalTrials.gov, and a literature overview of publications on the subject of pediatric oncology clinical research supported by expert opinions on the current situation and challenges.

RESULTS

The SIOP global mapping survey received responses from 47 of 54 African countries, of which 23 have active clinical research programs. A preliminary search of ClinicalTrials.gov showed that only 105 (12.1%) of 868 African oncology studies included children and adolescents. Of these, 53 (50.5%) were interventional trials according to the registry’s classification. The small number of African trials for children and adolescents included palliative care and leukemia trials. In African oncology journals and international pediatric oncology journals, < 1% of the pediatric oncology publications come from Africa. Services and research were strengthened by international collaboration. National studies focused on clinical needs, local challenges, or interventional priorities. Both the literature review and the expert opinions highlight the need to expand clinical research in Africa, despite ongoing regional instability and lack of resources.

CONCLUSION

While a low number of pediatric clinical treatment trials are open to African children and adolescents, clinical research of high quality is being done in Africa. Several initiatives are stimulating the development of the research capacity across the continent, which should increase the publication output.

Installing oncofertility programs for common cancers in limited resource settings (Repro-Can-OPEN Study): An extrapolation during the global crisis of Coronavirus (COVID-19) pandemic

PURPOSE

The state of limited resource settings that Coronavirus (COVID-19) pandemic has created globally should be taken seriously into account especially in healthcare sector. In oncofertility, patients should receive their fertility preservation treatments urgently even in limited resource settings before initiation of anticancer therapy. Therefore, it is very crucial to learn more about oncofertility practice in limited resource settings such as in developing countries that suffer often from shortage of healthcare services provided to young patients with cancer.

METHODS

As an extrapolation during the global crisis of COVID-19 pandemic, we surveyed oncofertility centers from 14 developing countries (Egypt, Tunisia, Brazil, Peru, Panama, Mexico, Colombia, Guatemala, Argentina, Chile, Nigeria, South Africa, Saudi Arabia, and India). Survey questionnaire included questions on the availability and degree of utilization of fertility preservation options in case of childhood cancer, breast cancer, and blood cancer.

RESULTS

All surveyed centers responded to all questions. Responses and their calculated oncofertility scores showed different domestic standards for oncofertility practice in case of childhood cancer, breast cancer, and blood cancer in the developing countries under limited resource settings.

CONCLUSIONS

Medical practice in limited resource settings has become a critical topic especially after the global crisis of COVID-19 pandemic. Understanding the resources necessary to provide oncofertility treatments is important until the current COVID-19 pandemic resolves. Lessons learned will be valuable to future potential worldwide disruptions due to infectious diseases or other global crises.

The evaluation of induction chemotherapy regimens for high-risk neuroblastoma in South African children. Pediatr Hematol Oncol 2020;37:300-313. [PMID: 32075464 DOI: 10.1080/08880018.2020.1717698]

Achieving remission after induction therapy in high-risk neuroblastoma (HR-NB) is of significant prognostic importance. This study investigated remission after induction-chemotherapy using three standard neuroblastoma protocols in the South African (SA) setting. Retrospective data of 261 patients with HR-NB diagnosed between January 2000 and December 2016, who completed induction chemotherapy with standard treatment protocols were evaluated. The treatment protocols were either OPEC/OJEC or the St Jude NB84 protocol (NB84) or rapid COJEC (rCOJEC). The postinduction metastatic complete remission (mCR) rate, 2-year overall survival (OS) and 2-year event free survival (EFS) were determined as comparative denominators. The majority (48.3%; n = 126) received OPEC/OJEC, while 70 patients received (26.8%) rCOJEC and 65 (24.9%) NB84. Treatment with NB84 had the best mCR rate (36.9%), followed by OPEC/OJEC (32.5%) and rCOJEC (21.4%). The 2-year OS of treatment with NB84 was 41% compared to OPEC/OJEC (35%) and rCOJEC (24%) (p = 0.010). The 2-year EFS of treatment with NB84 was 37% compared to OPEC/OJEC (35%) and rCOJEC (18%) (p = 0.008). OPEC/OJEC had the least treatment-related deaths (1.6%) compared to rCOJEC (7.1%) and NB84 (7.5%) (p = 0.037). On multivariate analysis LDH (p = 0.023), ferritin (p = 0.002) and INSS stage (p = 0.006) were identified as significant prognostic factors for OS. The induction chemotherapy was not significant for OS (p = 0.18), but significant for EFS (p = 0.08) Treatment with NB84 achieved better mCR, OS and EFS, while OPEC/OJEC had the least treatment-related deaths. In resource-constrained settings, OPEC/OJEC is advised as induction chemotherapy in HR-NB due to less toxicity as reflected in less treatment-related deaths.

The importance of local control management in high-risk neuroblastoma in South Africa

PURPOSE

To investigate the impact of local therapies on high-risk neuroblastoma (HR-NB) outcomes in South Africa.

METHODS

Data from 295 patients with HR-NB from nine pediatric oncology units between 2000 and 2014 were analysed. All patients received chemotherapy. Five-year overall (OS) and event free survival (EFS) were determined for patients who had received local therapy, either surgery or radiotherapy or both.

RESULTS

Surgery was performed in only 35.9% (n = 106/295) patients. Surgical excision was done for 34.8% (n = 85/244) of abdominal primaries, 50.0% (n = 11/22) of thoracic primaries; 22.2% (n = 2/9) neck primaries and 66.7% (n = 8/12) of the paraspinal primaries. Only 15.9% (n = 47/295) of all patients received radiotherapy. Children, who had surgery, had an improved five-year OS of 32.1% versus 5.9% without surgery (p < 0.001). Completely resected disease had a five-year OS of 30.5%, incomplete resections 31.4% versus no surgery 6.0% (p < 0.001). Radiated patients had a five-year OS of 21.3% versus 14.2% without radiotherapy (p < 0.001). Patients who received radiotherapy without surgical interventions, had a marginally better five-year OS of 12.5% as opposed to 5.4% (p < 0.001). Patients who underwent surgery had a longer mean overall survival of 60.9 months, while patients, who were irradiated, had a longer mean overall survival of 7.9 months (p < 0.001). On multivariate analysis, complete metastatic remission (p < 0.001), surgical status (p = 0.027), and radiotherapy status (p = 0.040) were significant predictive factors in abdominal primaries.

CONCLUSION

Surgery and radiotherapy significantly improve outcomes regardless of the primary tumor site, emphasizing the importance of local control in neuroblastoma.

Overall survival for neuroblastoma in South Africa between 2000 and 2014

BACKGROUND

Outcome data for neuroblastoma in sub-Saharan Africa are minimal, whereas poor outcome is reported in low- and middle-income countries. A multi-institutional retrospective study across South Africa was undertaken to determine outcome.

METHODS

Patients treated between January 2000 and December 2014 in nine South African pediatric oncology units were included. Kaplan-Meier curves and Cox regression models were employed to determine two-year survival rates and to identify prognostic factors.

RESULTS

Data from 390 patients were analyzed. The median age was 39.9 months (range, 0-201 months). The majority presented with stage 4 disease (70%). The main chemotherapy regimens were OPEC/OJEC (44.8%), St Jude NB84 protocol (28.96%), and Rapid COJEC (22.17%). Only 44.4% had surgery across all risk groups, whereas only 16.5% of high-risk patients received radiotherapy. The two-year overall survival (OS) for the whole cohort was 37.6%: 94.1%, 81.6%, and 66.7%, respectively, for the very-low-risk, low-risk, and intermediate-risk groups and 27.6% for the high-risk group (P < 0.001, 95% CI). The median survival time for the whole group was 13 months (mean, 41.9 months; range, 0.1-209 months). MYCN-nonamplified patients had a superior two-year OS of 51.3% in comparison with MYCN-amplified patients at 37.3% (P = 0.002, 95% CI).

CONCLUSIONS

Limited disease had an OS comparable with high-income countries, but advanced disease had a poor OS. South Africa should focus on early diagnosis and implementation of a national protocol with equitable access to treatment.

Hypodipsic hypernatraemia in a miniature schnauzer

Normovolaemic hypernatraemia as a result of a suspected congenital primary hypodipsia was diagnosed in a young male Miniature Schnauzer. Despite an elevated serum sodium concentration, the dog did not appear dehydrated on physical examination and the urine osmolality: plasma osmolality ratio was greater than 4; antidiuretic hormone deficiency was therefore not suspected. Basal serum cortisol and thyroxine concentrations were normal. Plasma aldosterone concentration and plasma renin activity (37 pmol l-1 and 1.55 ng dl-1 h-1 respectively) were within normal range. A defective central thirst regulation mechanism was suspected as the dog was totally disinterested in drinking water despite the chronically elevated serum sodium concentration. Excessive ingestion of water mixed with food, and milk resulted in hyponatraemia and associated cerebral oedema. On stabilisation of the dog's condition, a calculated fluid intake based on daily maintenance fluid requirements was prescribed to prevent recurrence of hypernatraemia and hyponatraemia, and associated signs of central nervous system disease. The dog was in apparent good health with controlled fluid intake when examined 230 d later.