``They're used for treating patients who have had skin grafts or had fingers or limbs reattached to their bodies,'' Ms Laing said.

``After a serious trauma or injuries, a person's veins are damaged and can no longer remove blood from that body part and the blood starts to congeal.

``For example, if someone loses their finger in an accident and then it is surgically reattached, the blood in the veins at the end of the finger would be so congealed that new blood couldn't get through to the finger.

``In these cases we could use the leeches but usually as a last resort.

``I would attach them to the finger and they would eat up all of the congealed blood and then the clean blood could flow through.''

Ms Laing said she ``fell into'' looking after the leeches, who are of the Richardsonianus australis breed and are all hermaphrodites.

``When I started work here, I was basically the only one who was comfortable putting them on people so when the previous person retired it all sort of fell into my lap. At first it was a steep learning curve because I didn't have any specialised training in looking after them but after 11 years I'm an expert.''

Liverpool Hospital's leech program is the only one in the state and Ms Laing supplies hospitals in need of the animals, sending them out through the post.

She said leech saliva has some impressive qualities. ``It contains an anti-inflammatory property as well as local anesthetic and 28 other useful chemicals.''