Montse Carrasco, Jordi Clanxet, Luis Feo, Jordi Puig
Thrombocytopenia is common in dogs and has a wide range of underlying causes, including vector-borne infectious diseases, the relative frequency of which may vary geographically. This retrospective cross-sectional study aimed to characterise the causes and clinicopathological features of thrombocytopenia in a hospital-based cohort of dogs evaluated at a mixed primary and referral veterinary hospital in Barcelona, Spain, and to identify differences across diagnostic categories, particularly those associated with primary immune thrombocytopenia (pITP). Medical records of dogs diagnosed with thrombocytopenia between 2021 and 2023 were reviewed. Of 612 dogs identified, 266 met the inclusion criteria. Neoplasia was the most common diagnosis (31.6%), followed by infectious diseases (24.4%), inflammatory or immune-mediated disorders (16.2%), miscellaneous conditions (15.4%) and primary immune thrombocytopenia (12.4%). Vector-borne diseases accounted for 10.9% of cases, mainly leishmaniosis and babesiosis. Dogs with neoplasia were older than those in other groups. Clinical bleeding was recorded in 42.5% of dogs and was most frequent in primary immune thrombocytopenia (78.8%). Fever was more common in infectious diseases, particularly non-vector-borne diseases. Albumin concentration was higher in primary immune thrombocytopenia than in infectious disease groups, whereas globulin concentration was higher in vector-borne diseases. Dogs with primary immune thrombocytopenia had lower platelet counts than all other groups. In this hospital-based cohort, neoplasia was the most common diagnostic category among dogs with thrombocytopenia, whereas vector-borne diseases were of intermediate frequency compared with reports from other European hospital-based cohorts. Distinct clinicopathological patterns, particularly severe thrombocytopenia and cutaneous haemorrhage, may help clinicians differentiate pITP from other causes of thrombocytopenia.