A woman who was walking her dogs at Willaston, north of Adelaide, has told how a koala "bit and hung on" to her leg as she tried to keep her pets away from the animal.

Mary Ann told 891 ABC Adelaide's breakfast program how the koala latched on to her leg after she put herself between her dogs and the animal.

"I had to put my fingers in its mouth and prise open its jaws to get my leg out," she said.

"There was a lot of blood; it made a very big hole."

Mary Ann said the koala then rolled onto its back and waved its legs around before rolling over and ambling off to the nearest tree.

She was forced to hobble 2.5 kms to her home and then waited for her daughter to arrive and take her to Gawler Hospital.

Mary Ann was left with a nasty wound to her leg after her encounter with a wild koala. ( Supplied: Lucy Alderton )

"I had 12 stitches and...was on IV antibiotics for four days," Mary Ann said.

After four days in hospital and a week of rest and physiotherapy, Mary Ann said her leg has healed nicely.

"It is a little bit sore, but it has recovered quite well," she said.

Mary Ann said her dogs charged the koala after she became distracted while texting her daughter.

"I don't blame the koala at all; they are wild animals and shouldn't be approached."

Humans and koalas interacting more

With increased development in areas where koalas live, Department of Environment, Water and Natural Resources animal welfare manager Dr Deb Kelly said interactions are becoming more common.

"From a koala's perspective, all he was trying to do was climb a tree," Dr Kelly said.

"Unfortunately that tree happened to be Mary Ann's leg."

Dr Kelly said the koala would not have been deliberately trying to attack Mary Ann.

"The best defence for a koala is to get up high."

In times of extreme heat it was common for koalas to seek water, increasing the chances of interactions between the animals and humans, but Dr Kelly said finding an animal on the ground was not an invitation to approach and pat them.

"When koalas are distressed, they just get to the point of saying 'I don't care anymore' and they just sit there and will let people pat them," she said.

"People think that they are tame and they like being patted, but the fact is they are just terrified and want to be left alone."