Lomustine, vincristine, procarbazine and prednisolone (LOPP) chemotherapy has been suggested to be an effective treatment for dogs with naïve non-indolent T-cell lymphoma (TCL). Studies evaluating prognostic factors for dogs with TCL treated with LOPP chemotherapy are lacking. The aim of this retrospective study was to assess potential prognostic factors for canine naïve non-indolent TCL treated with the LOPP protocol. This was a retrospective cohort study of naïve non-indolent TCL treated with the LOPP chemotherapy protocol at a single specialty veterinary oncology clinic. Sixty-seven dogs met the inclusion criteria. The outcomes assessed included progression free survival (PFS), overall survival time (OST) and duration of complete response (DCR). The overall median PFS was 118 days (range 7-2302 days). The median OST was 202 days (range 8-2302 days). The overall median DCR was 316 days (range 38-2261 days). Number of treatments administered (p < .0001), multicentric disease (p = .044) and the presence of hypercalcaemia (p = .006) were prognostic indicators for PFS. Increasing number of treatments (p < .0001) and age (p = .0088) were prognostic indicators for OST. To our knowledge, this is the first study to describe hypercalcaemia as a positive prognostic indicator of PFS for TCL treated with LOPP chemotherapy.LOPP chemotherapy can be considered as a first-line treatment protocol against naïve hypercalcaemic non-indolent TCL.

Background Gastrointestinal stromal tumor (GIST) is a malignant mesenchymal neoplasm described in humans, dogs, and cats. A hallmark of diagnosis for GISTs is positive immunohistochemical labelling with c-Kit (CD117). The differentiation of GIST from other mesenchymal neoplasms of the gastrointestinal tract is pivotal to allow for initiation of appropriate treatment. In humans, cystic GIST has been described, though this has not been reported in dogs. In humans, the cystic form of GIST has been associated with a favorable prognosis. In the present paper, we report a case of multilocular cystic GIST in a dog, which has not previously been described in this species. Case presentation A ten-year-old, male-entire Maltese terrier mix breed dog presented with a large cystic mural mass of the duoedenum and orad jejunum. Histopathology and positive immunohistochemical staining with CD117 confirmed a diagnosis of GIST. No evidence of metastasis was detected on routine staging with abdominal sonography and thoracic radiography at the time of diagnosis. Surgical resection was performed and toceranib therapy was initiated post-operatively. Metastasis was documented 251 days after surgery on computed tomography. Due to clinical deterioration, the patient was humanely euthanised 370 days after surgical excision. Conclusions There are few differential diagnoses for large multilocular cystic intra-abdominal masses in dogs. This case presents a previously undescribed presentation of gastrointestinal stromal tumor in the dog as a predominantly multilocular cystic mass. It remains unclear if the cystic form of GIST may represent a favorable prognosis in dogs.