WSU study ties refrigerated platelets to less bleeding in dogs

Platelets that Washington State University kept in a refrigerator for up to 21 days improved or prevented bleeding in 19 of 27 transfusions given to dogs with low platelet counts. The study, from the university's Veterinary Teaching Hospital, is the first clinical evidence that cold-stored platelets work in dogs, according to WSU.

Platelets stored at room temperature last only a few days and need constant agitation. A three-week shelf life would give hospitals another way to keep platelets on hand for the rare dog that needs them.

"It is hard to overstate how important the ability to transfuse platelets is," said Dr. Jillian Haines, a small animal internal medicine veterinarian who directs the hospital's blood bank and led the work.

"It's not needed often," Haines said, "but when it is needed, it is the only option. These products can be lifesaving."

Bleeding scores fell within four hours of transfusion

The paper, published online October 23rd in the Journal of Veterinary Internal Medicine, looked back at 24 dogs that received 27 cold-stored platelet transfusions between March 2022 and October 2024. The platelets were stored at 4°C for an average of 12.4 days before use.

Bleeding was scored with a canine bleeding assessment tool before each transfusion and again at one and four hours. In dogs that were bleeding, the average score fell from 3.15 to 2.21 at four hours, a drop the authors found significant. Bleeding improved or was prevented in 70% of transfusions.

No transfusion reactions were recorded, and 79% of the dogs survived to discharge.

The dogs' platelet counts barely moved, from an average of 23,000 per microliter before transfusion to 28,000 after, a change the authors did not find significant. The gain the study measured was in bleeding.

Spontaneous bleeding accounted for nine of the transfusions, surgery for six and minimally invasive procedures for 12. Immune-mediated thrombocytopenia was the most common underlying disease.

The study was retrospective, from one hospital, with no comparison group.

Longer-lasting platelets for dogs are already on the market

Haines' group showed in a 2023 laboratory study that canine platelet concentrates largely held their function for up to 21 days at 4°C, with no bacterial growth. The new paper is the group's first test of cold-stored platelets in patients.

Other stored platelet products already exist for dogs. BodeVet makes StablePlate RX, a freeze-dried canine platelet product for acute uncontrolled bleeding, and named HemoSolutions, Blue Ridge Veterinary Blood Bank and Northwest Veterinary Blood Bank as distributors at its 2018 launch. Two dogs in the WSU study also received it.

Frozen canine platelets stabilized with DMSO were sold in the U.S. too, and a 2020 multicenter clinical trial compared the two.

Human medicine went further first. The FDA issued guidance in June 2023 that lets blood establishments make platelets stored at 1°C to 6°C for actively bleeding patients when conventional platelets are not available or practical.

WSU says blood banks need only minor changes

The university says the method needs only minor changes to existing blood processing. Cold-stored platelets are less prone to bacterial growth, do not need constant agitation and ship easily, Haines said.

The hospital now keeps a routine supply, and she has trained staff from other institutions.

For emergency and specialty hospitals, that could mean platelets on the shelf instead of a scramble for a donor. Veterinary blood banks could make and ship cold-stored platelets. For makers of freeze-dried and frozen platelets, it is another option for clinics, backed so far by one retrospective, single-hospital study.

As with the LatusPet canine blood test we covered in July, the evidence is still early. Haines hopes to study the best dose, better ways to measure whether a transfusion worked in each dog, and whether the platelets stay effective beyond three weeks.

The next question is dose.

Source: Washington State University