Retrospective comparative analysis of some clinical and clinicopathological eatures of canine lymphoma from Italy and Thailand

Non-Hodgkin’s lymphoma is one of the most common hematopoietic tumor in dogs and represents 7—24% of all canine tumours. Middle-aged dogs and some purebreds (i.e. Boxer, Bull mastiff, etc.) are more affected. Few studies regarding the distributions of lymphoma subtypes in different countries have been published. The aim of this retrospective study was to compare some clinical data and the cyto-morphological aspects of canine lymphoma cases collected in two different countries, Italy (Pisa) and Thailand (Bangkok). This study included 192 dogs with lymphoma (cytologically and/or histologically diagnosed) collected at the Veterinary Teaching Hospital of Pisa (VTHP) between January 2010 and May 2017, and 436 dogs collected at the VTH of Bangkok (VTHB) between January 2015 and November 2017. The data analysed included breed, size (small, medium, and large), sex, age, and lymphoma classification (anatomo-clinical, tumor grade, immunophenotype). Differences for age have been evaluated by Mann-Whitney test, while other parameters have been investigated with the Chi-squared or Fisher’s exact tests (P-value of <0.05 was statistically significant). Breeds affected by lymphoma were compared with the whole canine population presented at the same period in the two facilities. Dobermann and Rottweiler for VTHP and Golden Retriever for VTHB were significantly overrepresented. VTHB-dogs were considerably older (median 9 vs. 8 years) and were mostly small sized breeds compared to the population at VTHP. More than 90% of lymphomas were classified as high-grade in both groups. Multicentric lymphoma (83%) was significantly more frequent in the VTHP. Extra-nodal (34%) and cutaneous lymphomas (26%) were significantly more frequent in the VTHB. B-cell lymphomas (71%) were significantly more frequent in VTHP and T-cell lymphomas (34%) in VTHB. Striking differences were found in the signalment data and the higher frequency of cutaneous lymphomas in VTHB dogs should be pointed out. Moreover, such findings probably influenced the immunophenotype results, since almost all cutaneous forms were T-cell lymphomas. Different breed and size distribution, lifestyle and environmental factors could influence the two study populations, as shown by our results.