Electrochemotherapy as Monotherapy Provides a Novel, Organ-Sparing, Long Term Treatment Option for Control of Feline Third Eyelid Squamous Cell Carcinoma: A Report of Two Cases

Abstract

Background: Squamous cell carcinoma (SCC) is one of the most common malignant eyelid tumors in cats, especially in white-haired individuals chronically exposed to sunlight. Electrochemotherapy (ECT), which combines bleomycin administration with transient membrane permeabilization through electric pulses, has demonstrated efficacy in periocular epithelial tumors. However, its use as monotherapy for third eyelid SCC has not been reported. Objectives: To describe the clinical outcomes, feasibility, and safety of ECT as sole treatment for third eyelid SCC in two cats. Methods: Two client-owned cats with histologically confirmed SCC restricted to the third eyelid underwent full staging, including thoracic radiographs and head CT. Both were treated with a single ECT session involving systemic and intratumoral bleomycin followed by electric pulses. Follow-up consisted of clinical and imaging evaluations for up to 930 days. Results: Both cats achieved complete remission after one session. No recurrence or metastasis was detected during long-term follow-up. Treatment was well tolerated, with only mild, self-limiting inflammation. Ocular structures and function were fully preserved, without systemic toxicity. Owners expressed high satisfaction due to the non-invasive nature of ECT and the avoidance of enucleation. Conclusions: This is the first report of successful ECT monotherapy for feline third eyelid SCC. The findings support ECT as a safe, effective, and organ-sparing option when surgery is declined or contraindicated, highlighting its potential role in feline ocular oncology and comparative oncology. Although promising, the very limited sample size (n = 2) prevents strong conclusions, and results should be regarded as preliminary observational evidence.