Case report highlights electrochemotherapy in rare canine oral lymphoma

A newly published case report adds an unusual but clinically relevant data point to veterinary oncology: bleomycin-based electrochemotherapy achieved prolonged local control in a dog with recurrent oral CD8-positive epitheliotropic T-cell lymphoma, even after progression on oclacitinib. In the report, a 13-year-old Beagle had multifocal lesions affecting the gingiva and buccal mucosa, then later experienced visible regression and sustained local control after serial electrochemotherapy treatments. At day 608, the dog had no gross oral lesions and remained clinically well, without evidence of systemic dissemination. (frontiersin.org)

That matters because oral epitheliotropic T-cell lymphoma is uncommon in dogs, and the evidence base for how best to manage it remains thin. The authors note that information on prognosis and optimal treatment is limited. More broadly, electrochemotherapy has been established in veterinary oncology as a local treatment platform for accessible tumors, using electric pulses to increase intracellular uptake of drugs such as bleomycin. Consensus guidance and reviews describe it as a validated option for selected superficial and oral tumors, either alone or alongside surgery, chemotherapy, or radiotherapy. (frontiersin.org)

In this case, the dog initially responded to oclacitinib, with reduced lesion size and number, but the disease later progressed after 149 days. The team then used intravenous bleomycin at 20 mg/m² followed by electric pulse delivery with a four-needle electrode at 1000 V/cm for eight pulses. Two sessions were performed on days 205 and 238, producing marked lesion reduction and prolonged local control. When recurrent erythematous lesions later appeared on the upper and lower lip mucosa, histology again confirmed T-cell lymphoma, and a third electrochemotherapy session was given on day 555. (frontiersin.org)

One of the more interesting findings was in the regional lymph node. On day 354, the left mandibular node enlarged, but histopathology showed extensive necrosis, which prevented a definitive assessment of lymphoma involvement. Residual CD3-positive lymphocytes were present, yet flow cytometry and PARR did not confirm a neoplastic lymphoid population. The authors characterize these as unusual necrotic changes, raising the possibility that electrochemotherapy-related local or regional effects may complicate post-treatment interpretation of nodal disease, though that remains an inference rather than a proven mechanism. (frontiersin.org)

The broader literature supports the plausibility of this approach, but also underscores how early the evidence still is. A 2007 preliminary study of electrochemotherapy for localized lymphoma in companion animals reported complete responses in all six enrolled patients, with durations ranging from one week to three years. More recent veterinary guidelines say electrochemotherapy is effective for superficial or oral tumors accessible to electrodes, while also warning clinicians about treatment planning issues such as pain control, tissue necrosis, fistula risk, airway concerns for caudal oral tumors, and cumulative bleomycin exposure. (pubmed.ncbi.nlm.nih.gov)

Industry and academic discussion around oral tumor use has also been moving forward. A 2022 case series of 19 dogs with oral tumors treated palliatively with repeated electroporations plus intravenous bleomycin found good local responses, rapid quality-of-life improvement, and minimal toxicity attributable to electroporation, although survival remained limited and histologies were mixed. Reviews of oral and maxillofacial oncology likewise position electrochemotherapy mainly as an option for selected cases where surgery or radiotherapy are not feasible, not accepted, or are being used in combination with local control strategies. (frontiersin.org)

Why it matters: For veterinarians, especially oncologists, dentists, and referral clinicians, this report suggests electrochemotherapy may deserve consideration as a local control tool for rare oral lymphoid malignancies, not just the more commonly discussed oral melanoma or squamous cell carcinoma. It won't change standard practice on its own; this is still a single case report. But it does offer a concrete example of durable control in a difficult anatomic site, after medical management lost effectiveness, and it highlights the need for careful interpretation of post-treatment lymph node changes. For pet parents weighing quality of life, oral function, and the burden of more aggressive interventions, that could widen the conversation around salvage or palliative options. (frontiersin.org)

What to watch: The next step is better evidence, especially multi-case series or prospective studies that define which oral lymphoma patients benefit most, how often repeat sessions are needed, how to monitor regional nodes after treatment, and how electrochemotherapy compares with radiation-based local control in practice. Recent reports in other veterinary tumor settings suggest the field is still actively refining technique, electrodes, and indications. (pubmed.ncbi.nlm.nih.gov)