Blood Groups - Cat

Cats and dogs have very different blood grouping systems. Cats have an A-B blood group system and inherit blood types as a simple dominant trait where by A is dominant over B.

Cat blood can be classed as Group A, B or AB. Group A which can be either A/A or A/B is the most common blood type of domestic short and long haired cats in the UK.

Group B which is always B/B is very common in Devon Rex, Persians, British Shorthair, Somali, Himalayan and Birman breeds.

Rarely cats can also be group AB.

Autoantibodies

Both the blood donor and recipient should always be blood typed prior to transfusion. This is especially important in cats due to the occurence of autoantibodies.

Group A cats have low titres of anti-B antibodies.

Group B have high titres of anti-A antibodies and giving Group B cats type A blood can result in a potentially fatal transfusion reaction.

Blood group incompatilibility in Cats

Donor Group	Recipient group	Transfusion reaction
A	A	None
B	B	None
B	A	Slight
A	B	Potentially fatal

Simplified compatibility tests

Time is needed to determine full compatibility between the donor and recipient. This is not always possible in the emergency situation. In these cases it is possible to undertake simplified compatibility tests. These tests can be performed in minutes however are much less reliable.

They involve centrifuging 0.5mls of the donors blood and 0.5mls of the recipient blood in EDTA tubes hence separating red blood cells and plasma. Various amounts(as below) are then added to gether and blood smears are prepared.

Three tests need to be undertaken 1)The major test where 3 drops of plasma from the recipient and one drop of red blood cells from the donor are added together left for 1-3 minutes and then examined microscopically. If this reaction shows there is agglutination the transfusion should not be performed. 2)Minor test where 3 drops of donor plasma is added to 1 drop of recipient red blood cells.