IM02 - Multicenter Investigation of the Effectiveness of Therapeutic Plasma Exchange for Canine Immune-mediated Hemolytic Anemia

Abstract: Background - A knowledge gap exists regarding survival benefits of therapeutic plasma exchange (TPE) for canine immune-mediated hemolytic anemia (IMHA).

Hypothesis - TPE is associated with lower mortality than medical therapy alone.

Animals - Dogs treated for non-associative IMHA (1/1/2021-12/31/2023).

Methods - Multicenter retrospective cohort study including nine hospitals offering TPE and four not. Data, including disease severity, hospitalization duration, and survival, were compared between medically and TPE-treated dogs. Fisher’s exact and Mann-Whitney U tests were used for categorical and continuous/ordinal data, respectively; Kaplan-Meier analysis was used for long-term survival.

Results - 486 dogs were included: 71 receiving TPE and 415 receiving medical therapy. Canine Hemolytic Anemia Objective Scores were similar at presentation (median 3 for both; p = 0.56). Peak serum bilirubin was higher in the TPE group (median 7 versus 1.6 mg/dL, p < 0.0001). The TPE group was hospitalized longer (median 6 versus 4 days, p < 0.0001). Survival to discharge was not different (44/71, 62%, TPE cases; 292/415, 70%, medical cases; p = 0.26). For dogs with bilirubin > 20 mg/dL, 14/30 (47%) TPE cases and 18/59 (31%) medical cases survived to discharge (p = 0.16); of these, 13/14 (93%) TPE cases were alive 90 days following diagnosis compared to 3/7 (43%) medical cases (p = 0.055), although 11 medical dogs were lost to follow-up.

Conclusions and Clinical Importance - Dogs treated with or without TPE had similar survival to discharge. Further investigation into the impact of TPE on outcome of markedly hyperbilirubinemic dogs is needed.