Application of the "World Health Organization (WHO) Human Working Formulation" for the classification of canine lymphoma

Abstract

Lymphoma is a highly prevalent neoplasm in dogs. Globally, lymphoma has an approximate annual incidence of 20 - 100 occurrences per 100,000 dogs, a frequency close to human non-Hodgkin lymphoma. Although the specific aetiology remains uncertain, environmental variables and genetic predisposition are considered to play a significant impact in the spread of the disease, both in humans and dogs. In numerous studies, the World Health Organization (WHO) Human Working Formulation has been proven to be effective in the classification of canine lymphomas to achieve an accurate prognosis and apply best therapeutic regimen. Therefore, insight into the demographical, morphological and immunohistochemical criteria and their effect on canine lymphoma incidence may help to predict the possible risk factors of this disease. The purpose of the study is to characterise the potential lymphoma risk factors with the application of the WHO human working formulation for the classification of canine lymphoma. The study is based on epidemiological, clinical histological and immunophenotypic analysis of 104 confirmed canine lymphoma cases and 18 hyperplasia cases provided by the Australian Specialized Animal Pathology (ASAP), Melbourne, Australia. In this study, I show that neutered males have a considerably higher incidence of lymphoma than neutered females. However, neutered males were at decreased risk when compared with intact males. Middle to old aged male dogs ( 6-year-old) are significantly at increased risk of lymphoma in contrast to middle-aged females 'dogs. My data agrees with previous published studies and revealed that the prevalence of lymphoma in small breeds is lower when compared to large breeds. The majority of the cases included in my study affected primarily lymph nodes and spleens. Immunophenotyping of the 104 cases of lymphoma revealed that 78 cases were high-grade, 07 cases intermediate and 14 cases low-grade diffuse B-cell lymphomas. Moreover, I have also identified 03 cases T-Zone lymphoma, of which 2 are high-grade and 1 low-grade lymphoma. Immunophenotyping confirmed the T cell origin of the PTCL and the TCLL cases. In conclusion, these results highlight the benefit of applying the WHO Working Formulation for the classification of canine lymphomas to help with the prognosis and patient management and to inform the best treatment regimen.

Date of Award	2021
Original language	English