Ultraviolet Light-Induced Skin Cancer and the Safety of Sunscreen Use in Pets—An Important but Under Researched Aspect of Companion Animal Health

Ultraviolet (UV) light exposure is a recognised risk factor for dermal haemangiosarcoma (HSA) in dogs and dermal squamous cell carcinoma (SCC) in dogs and cats. These tumours cause substantial local disease and often require repeated surgery due to recurrence or de novo lesions, creating a notable welfare and financial burden. Research on preventing harmful UV exposure in pets is still in its infancy, particularly in relation to the safety of UV filters used in sunscreens. This review summarises the current evidence on UV-induced carcinogenesis, strategies to reduce UV exposure, and the safety of sunscreen ingredients in dogs and cats. UV light is strongly implicated in a range of dermatoses, from actinic keratosis to dermal HSA and SCC in dogs and cats, and the risk is likely higher in Australian pets. Indoor confinement during peak UV periods, shade, and sun-protective clothing can reduce exposure, with sunscreen an additional strategy. Sunscreen is relevant because UV-associated cancers typically develop in sparsely haired or hairless regions such as the nose and ventrum, making these areas suitable for targeted sunscreen application. Sunscreens containing non-nanoparticle zinc oxide appear safe for dogs and cats when ingestion is prevented or minimised, whereas the safety of organic UV filters remains unclear due to limited safety data in both humans and animals. Non-nanoparticle titanium dioxide is a possible alternative to zinc oxide and organic filters, but there is currently little information on its safety when ingested by dogs and cats. Overall, the available evidence supports sunscreen as a necessary component of UV-reduction strategies in pets, but substantial research is needed to determine the safety profiles of different UV filters and to establish evidence-based guidelines for their safe use.