Canine multiple myeloma: a retrospective case-control epidemiological survey in Italy

Introduction Multiple Myeloma (MM) represent <1% of all canine malignant tumours and 8% of all canine hematopoietic tumours. The aim of this study was to present epidemiological data of canine MM in Italy. Material and Methods The San Marco Veterinary Clinic data-base POA® system was searched between 2002-2014 for dogs diagnosed with MM (Group 1, n=65). Dogs presented within the same period were included as control (Group 2, n=47,873). Differences in sex, age, and body weight (BW) were compared between groups. Breed’s risk to develop MM was also evaluated. Overall prevalence, and prevalence compared to other malignant lymphoproliferative disorders (MLDs), was calculated. Results 47,949 dogs were included in the study; 76 dogs (prevalent cases) were diagnosed with MM (overall prevalence 0.16%) and 65 dogs were incident cases. The total incident cases with MLDs (i.e., lymphoma, lymphoid leukaemia, and MM) were 546 dogs (MM prevalence among all MLDs was of 11.9%). Dogs with MM were more likely female neutered (p=0.005) or intact male (p=0.024) compared to controls. There was a difference (p<0.0001) in age between Group 1 (median 124 months; range: 68-145) and Group 2 (median 78 months; range: 0-203). There was a difference (p=0.0002) in BW between Group 1 (median 26.4 Kg; range: 3.7-52.0) and Group 2 (median 16.0 Kg; range: 0.1-84.0). Twenty-two different breeds were affected with MM with Giant Schnauzer at increased risk (p<0.0001; OR = 16.52; 95% CI 5.72–47.7). Conclusion Giant Schnauzer, female neutered, intact male, higher BW, and older dogs are at increased risk to be diagnosed with MM.