This retrospective case series reports tolerability, safety and clinical outcomes for dogs with malignant epithelial rectal tumours treated with piroxicam rectal suppositories when curative-intent surgery was not performed. The report addresses a palliative-care setting where owners or clinicians opt against surgical resection and seek symptom control and possible tumour stabilisation using a non-steroidal anti-inflammatory agent administered rectally.
Piroxicam is an NSAID with reported activity in several canine tumour types and has previously been considered in management of colorectal and other epithelial neoplasms in veterinary medicine. The rectal route was used in this series because it allows local delivery in dogs with rectal masses and may be preferable when oral administration is impractical.
Medical records from a single UK referral hospital were retrospectively reviewed to identify dogs with malignant epithelial rectal tumours that received piroxicam suppositories. Dogs that underwent curative-intent surgery or received other anticancer agents were excluded from the analysis.
The dataset comprised eight dogs treated under routine clinical practice. Details such as exact dosing regimens, frequency, formulation specifics and standardisation of concurrent supportive treatments were not reported in the abstract.
Primary outcomes captured were owner-reported improvement in clinical signs and veterinarian-assessed tumour response using cRECIST (canine Response Evaluation Criteria for Solid Tumours). Secondary outcomes included overall survival time and progression-free survival; however, the abstract does not provide numerical survival or progression-free intervals.
Owner-reported signs reflect clinical benefit perceived at home, while cRECIST provides an objective framework for assessing changes in tumour size or status on veterinary evaluation.
Eight dogs were included in the series. Owner-reported clinical benefit was documented in four dogs. Of these four:
Veterinarian-assessed responses among the dogs with owner-reported benefit were: three dogs with stable disease and one dog achieving a complete response by cRECIST criteria. The abstract does not present detailed tumour measurements, time to response, or cohort-level survival statistics.
These findings indicate that in this small cohort, rectal piroxicam was associated with symptomatic improvement in half of treated cases and with objective stabilisation or reduction in tumour burden in some dogs.
Adverse events recorded in the series included:
The occurrence of renal marker elevations and one late oliguric acute kidney injury underscores the potential for renal toxicity with long-term piroxicam administration and the need for biochemical monitoring during therapy. Specific details about severity grading, management of adverse events, and whether events led to treatment discontinuation were not reported in the abstract.
The authors note several limitations that affect interpretation of the findings:
Because of these constraints, conclusions should be considered preliminary and hypothesis-generating rather than definitive.
In this retrospective series, rectal piroxicam suppositories were associated with improvement in clinical signs and, in some cases, objective tumour stabilisation or reduction in dogs with rectal carcinomas when curative-intent surgery was not performed. The findings suggest that piroxicam may be a palliative option for symptom control in selected patients.
However, the observed potential for renal adverse effects and other gastrointestinal signs indicates that clinicians should weigh potential benefits against risks and discuss these uncertainties with owners.
Based on the reported toxicities, the authors recommend regular serum biochemistry monitoring during piroxicam suppository therapy to detect renal marker elevations early.
Given the small, retrospective nature of the series and non-standardised treatment approaches, prospective, larger-scale studies with standardised dosing, systematic toxicity grading, objective tumour measurement schedules and defined survival endpoints are needed to better characterise efficacy, safety, optimal dosing and duration of rectal piroxicam in canine rectal carcinoma.