How Veterinary Patients might help human patients: a platelet clinical trial

By Beth Davidow, DVM DACVECC

When we discuss transfusions in veterinary medicine, we often talk about red blood cells and plasma but not platelets. Platelets transfusions are tricky and not commonly performed because platelet function is very affected by storage. Platelet concentrate is

The Components of blood can be centrifuged and separated to make various useful products.

made by slowly spinning blood to separate the platelets into the plasma and then spinning the plasma again to sediment the platelets. This concentrated product must be stored at room temperature and must be constantly rocking for the platelets to remain functional. Shelf life is only 5-7 days after production due to the risk of bacterial contamination.

Another reason we often don't do platelet transfusions is that platelets often only last minutes to hours in circulation in patients who have accelerated platelet destruction such as ITP (immune mediated thrombocytopenia). However, if an animal is catastrophically bleeding from the lack of platelets or starts bleeding into the brain, a platelet transfusion may be life saving.

Platelet Concentrate can be used for severe bleeding disorders in some dogs.

Sometimes, in the case of a bleed into the brain, you can't collect fresh whole blood fast enough to use that for platelets, and in these cases, platelet concentrate, if made and readily available, is ideal. In most of our hospitals, however, it is not cost effective to always have platelet concentrate on hand. However, when I visited the human Puget Sound Blood Bank, I was impressed by the full wall of floor to ceiling rocking cabinets full of bags of platelet concentrate.

Veterinary medicine has the opportunity to make a large advance in transfusion medicine, leading the way for an advance in human medicine. A research group in North Carolina has figured out a way to "freeze dry" canine platelets. These platelets come in a small plastic bottle and can be stored for 6 months in the refrigerator. Previous studies have shown that these platelets are functional and safe in canine research subjects (see below references). They are reconstituted by adding saline and can be given over 15-20 minutes.

ACCES is now participating in a multi-center trial run by Animal Blood Resources International, looking at these lyophilized platelets in dogs with thrombocytopenia (very low platelets). The goal is to enroll 100 patients at one of 5 hospitals around the country in order to examine whether these platelets really can stop active bleeding in dogs with platelet problems.

We have currently enrolled 8 patients in the study and we greatly appreciate those veterinarians who have referred patients to us. 6 of the 8 dogs, all of whom had severe active bleeding at admit, have been successfully treated. The study does provide the platelet product at no cost to the client and also pays for two complete blood counts and coagulation profiles.

If your pet has a platelet disorder, please discuss with your veterinarian whether your pet might qualify for this important research study.

References:
Bode AP, Lust RM, Read MS, and Fischer TH. Correction of the Bleeding Time with lyophilized platelet infusions in dogs on cardiopulmonary bypass. Clin and App Thromb/Hemost 2008; 14:38-54.

Bode AP and Fischer TH. Lyophilized Platelets: Fifty years in the making. Artif Cells Blood Substit Immobil Biotechnol. 2007; 35(1): 125-33

via blog.seattlepi.com

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