Small Animal News editor, Harriet Woodhall, brings us an article on the Pet Blood Bank, a fantastically important and lifesaving service.
Pet Blood Bank
Harriet Woodhall (Vet News Small Animal News Editor)
The Pet Blood Bank is a UK charity that supplies blood products to veterinary professionals for canine blood transfusions and has recently hit its 5000th donor in its seventh year as a charity.
Like human blood donations, there are certain criteria that dogs need to meet to ensure that donated blood is safe for a transfusion patient and not contaminated. The donor should: weigh more than 25kg, be aged between one and eight years old, have a good temperament, be up to date with vaccinations, never have traveled abroad, be fit and healthy and not be on any medication.
When a blood donation is made, the dog also needs to be blood typed so that any transfusions made are using the correct type. If given an unmatched type, the immune system will recognise the new cells as foreign and prematurely destroy them, which could lead to other complications. What causes the body to recognise foreign or self red blood cells is whether they have aminosaccharide molecules on the red blood cell membranes. As well as the presence/absence of these molecules, there are also very small differences in their structure, giving them antigenic properties.
A canine donor is normally classified as DEA (Dog Erythrocyte Antigen) 1.1 negative or positive, but the other major antigens are 1.2, 3, 4, 5, 6 and 7. DEA 1.1 negative patients should only receive 1.1 negative, whereas patients that are DEA 1.1 positive can receive both 1.1 negative and 1.1 positive. However, due to the lack of DEA 1.1 negative blood, it is always recommended that 1.1 positives receive 1.1 positive, so that supplies of 1.1 negative are preserved. The dog’s blood is screened to check Packed Red Cell Volume (PCV) and Total Solids (TS) before donation. The donors are also micro-chipped so that all blood can be traced, and have annual haematology and biochemistry screens. Once all criteria and tests are met then the dog is suggested to donate blood three to four times a year.
There are a range of blood products available:
Packed Red Blood Cells (PRBC)
Fresh Frozen Plasma (FFP)
Frozen Plasma (FP)
Fresh Whole Blood (FWB)
Stored Whole Blood (SWB)
Blood is taken from the jugular vein in the dog’s neck and put into a collection bag containing anti-coagulants. Once blood is collected from a donor, it is transported to a processing centre and is kept at 20 degrees Centigrade while travelling. The blood is then inspected and logged with a reference number for tracking purposes. Under sterile conditions, the tubing and needle are removed, blood is weighed and then centrifuged (spun at 3800 revolutions per minute) for 15 minutes to allow the red blood cells to separate from the plasma. The plasma and red blood cells are then stored separately and in special conditions to increase shelf life: plasma is stored in a minus eighty degrees Centigrade freezer, once frozen it can then be transferred into a minus thirty four degrees Centigrade freezer where it can be stored for up to five years. Red Blood Cells can only be stored for up to six weeks and are kept at four degrees Centigrade in specialist fridges.
Choosing which blood product to use depends on the reason for transfusion. For example, several diseases causing anaemia would require PRBC whereas conditions such as thrombocytopaenia (platelet deficiency) would need FWB. Some conditions could receive several suitable products but there are often superior products that are favoured if more than one option is available.
At present, only canine blood products are available from the bank. Feline patients that need transfusion can only receive fresh whole blood from emergency donors.