# Selective Removal of Plasma Proteins by Double-Filtration Plasmapheresis in Canine Blood: An Ex Vivo Study and Retrospective Report of In Vivo Clinical Treatments in Three Dogs

## TL;DR

This study shows that double-filtration plasmapheresis selectively removes certain plasma proteins in dogs, preserving albumin better than other proteins.

## Contribution

The study is one of the first to evaluate double-filtration plasmapheresis in dogs, demonstrating its semi-selective protein removal and potential clinical use.

## Key findings

- Ex vivo, DFPP with 1.5 plasma volumes caused 25% albumin loss and 41% globulin loss.
- Fibrinogen levels dropped significantly after 1.5 plasma volumes of DFPP.
- In vivo, DFPP showed significantly lower albumin reduction compared to globulin and fibrinogen.

## Abstract

Double-filtration plasmapheresis is a semi-selective plasma exchange modality that removes high-molecular weight substances, including immunoglobulin and immune complexes, while minimizing the loss of albumin and the consequent need for substitution fluids. In contrast to conventional plasmapheresis, with double-filtration plasmapheresis the volume of discarded plasma is significantly reduced, lowering the volume of the replacement fluid and the associated risk for transfusion reactions. This technique has been increasingly used in human medicine to treat different immune-mediated, hematological, and neurological conditions, but reports regarding its use in dogs are scarce. The aim of this study is to evaluate the quantitative net loss of different plasma proteins fractions in an ex vivo model using canine blood with double-filtration plasmapheresis. A semi-selective protein removal is demonstrated ex vivo, with a significant sparing effect on albumin when 1.5 plasma volume are processed. A description of the use of double-filtration plasmapheresis in three dogs affected by immune-mediated diseases is additionally presented. The obtained results in vivo demonstrate that a semi-selective protein removal occurs in dogs, as the median percentage reduction in albumin is significantly lower compared to total globulin and fibrinogen. Double-filtration plasmapheresis seems to be a promising plasma-exchange modality deserving investigations in veterinary patients.

Double-filtration plasmapheresis (DFPP) is a plasma-exchange modality that allows selective clearance of high-molecular-weight proteins, potentially minimizing albumin loss and the need for volume replacement. Reports concerning DFPP use in dogs are scarce. This study evaluates the quantitative net loss of different plasma proteins fractions in an ex vivo model using canine blood processed via DFPP. DFPP treatment with INUSpheresis® processing 1.5, 2, and 3 plasma volumes (PVs) was performed. Plasma proteins fractions were measured in the reservoir blood bag at baseline (pre-treatment) and in the effluent bag at the end of each target PV exchanged to calculate the net loss of selected plasma proteins. At 1.5 PV, net globulin and albumin loss was 41 and 25% respectively. At 3 PV, net globulin and albumin loss was 47 and 40%, respectively. Fibrinogen concentration was unmeasurable low in the reservoir blood bag after processing 1.5 PV. INUSpheresis® allows selective plasma proteins removal, with a sparing effect on albumin at 1.5 PV. Selectivity is, however, progressively reduced with incremental target PV. A description of five DFPP treatments in three dogs is additionally presented. Semi-selective protein removal was also demonstrated in vivo, with a significantly lower percentage reduction in albumin compared to total globulin (p = 0.01) and fibrinogen (p = 0.007).