“When owners first come, here they often say they have no idea there is a need for dog blood.”

So says Robyn Turner, a transfusion and ICU nurse at the Royal Vetinary College in Brookmans Park.

Sitting in the college cafe, Robyn tells me more about the process.

“It is one of the simplest things we can do for a cat or dog,” says the 38 year old, who has worked at the college for 10 years.

“And it’s one of the loveliest gifts an owner of a dog can give to someone else’s dog - it is something that is desperately needed and it’s one of the most life saving things we can do for our patients.”

Dog and cat blood is needed by the college so it can carry out surgeries and life saving treatments for its patients in the same way that humans donate blood to hospitals.

Robyn has been in charge of the little-known programme since she started at the college and the service has gone from strength to strength.

“At the moment we have about 80 dogs on the books and 20 cats, but we always need more,” she said. “Depending on the size of the dog they can use up to 10 units at a time - which is a lot of blood.

“Recently we have had some of our donors retire, so we are looking for more volunteers to come forward.”

Any breed of dog or cat can donate once every two months, as long as they are between one and seven years old.

The donation process takes about an hour for dogs, although once the tube is in the actual blood taking only lasts five minutes or so.

Dogs are placed on the table and a small patch of hair is shaved away at the neck, a local anaesthetic cream is then rubbed on the skin to weaken the sting of the needle.

A unit of blood – around 450ml of blood from a dog – is taken, separated into red blood cells and plasma and then stored.

The plasma can be frozen for up to a year and red blood cells stored in a fridge for up to five weeks.

This means that each unit can be used to help two other dogs.

“We always work with the dog, we always go at the dogs pace,” says Robyn.

“We don’t rush them at all because we want them to have a pleasant positive experience - which is why we give them lots of treats and biscuits and fuss.

“We want them to want to come back again and again and not be stressed.”

For cats the process is slightly different.

Cat blood isn’t stored by the RVC and is taken directly from one cat and given immediately to another and donors are only called in when there is an emergency.

After a donation has been made animals are then treated to a bowl of food – “like we are given tea an biscuits after we give blood,” Robyn says. Owners also receive a certificate of achievement after the first donation and a donor tag to put on their pets collar after the second.

Robyn says these tags help spread the word about the blood banks, dog walkers often ask about the unusual tag and then sign their own dog up to the list.

Information about the blood bank has mostly spread via word of mouth of the years.