Primary frontal sinus squamous cell carcinoma in three dogs treated with piroxicam combined with carboplatin or toceranib

In human medicine, primary frontal sinus squamous cell carcinoma (pFS‐SCC) is not frequently reported. In veterinary medicine, frontal sinus SCC is exclusively described as an extension of nasal cavity SCC. To our knowledge, this is the first publication concerning canine pFS‐SCC, diagnosed using histology or cytology and medical imaging, in three dogs. The tumours extended into the orbit or brain cavity, without nasal involvement. Treatment was initiated with piroxicam–carboplatin. Prolongation of carboplatin delivery with a low dose intensity was performed on dogs with a favourable initial response. Dog 1 achieved a complete remission (CR), but was euthanized 344 days after start of therapy. Dog 2, still alive 3 years after start of therapy and in CR, received 14 carboplatin deliveries. In dog 3, after changing the treatment protocol into piroxicam–toceranib, a significant tumour reduction occurred, but the dog was euthanized after 195 days because of a relapse.