Phoebe Katsikioti, Vicki Black

Langford Small Animal Hospital, University of Bristol, Bristol, United Kingdom

Objectives

Immune-mediated anaemias encompass regenerative forms such as immune-mediated haemolytic anaemia (IMHA) and non-regenerative immune-mediated anaemias (nrIMA), where bone marrow erythroid precursors are targeted. Although historically considered distinct, emerging evidence suggests overlap, with peripheral erythrocyte destruction reported in nrIMA. Dogs with IMHA are well established as hypercoagulable, warranting routine thromboprophylaxis. The coagulation status of dogs with nrIMA remains poorly characterised despite reports of thromboembolic complications and increased mortality. This study evaluated the coagulation profile of dogs with nrIMA using point-of-care viscoelastic testing (VCM-Vet, Entegrion, Inc.), hypothesising that coagulation abnormalities would be present. A secondary aim was to assess haemolytic features overlapping with IMHA.

Methods

Dogs presenting with non-regenerative anaemia were prospectively enrolled, with two additional retrospective cases, from a single referral centre. Residual blood VCM-Vet analysis was performed. Diagnosis of nrIMA required cytological and/or histological bone marrow confirmation for inclusion. Dogs were classified as hyper- or hypocoagulable if ≥2 VCM parameters deviated from published reference intervals. Additional variables included total bilirubin, Coombs’ testing, serum cobalamin, diagnostic imaging findings, thromboembolic events and survival to discharge.

Results

Nine dogs were enrolled; eight diagnosed with precursor-targeted immune-mediated anaemia (PIMA) and one with pure red cell aplasia. All dogs demonstrated hypercoagulability (9/9, 100%), most frequently characterised by increased maximum clot formation (MCF) and amplitude (A10/A20). Hyperbilirubinaemia was identified in 56% of cases, indicating possible concurrent haemolysis. Three dogs experienced suspected thromboembolic events based on specialist neurological assessment.

Statement: Impact/ Clinical Significance

Some dogs with nrIMA demonstrate hypercoagulability with clinically relevant thromboembolic complications, supporting consideration of routine thromboprophylaxis in this population.