SPCA Otago director of animal welfare Dr Helen Beattie said anyone who had visited the Opoho animal shelter in the past weeks should check their body for lesions from the fungal skin infection.
"It's not a worm at all; it causes scaly, red, round lesions.''
People who noticed unusual patches on their skin should seek medical advice, Dr Beattie said.
The "unsightly'' disease was contagious but treatable.
Ringworm was transmissible between "various mammals'' but SPCA Otago was most concerned about cats, dogs and humans.
The shelter was closed to the public on Wednesday.
The main reason for the lock-down was the fear of a small child cuddling an infected animal and spreading the disease at their school.
"We don't want to be sending kids to school with a dose of ringworm.''
The lesions appeared on mammals after an "incubation period'' between seven days and three weeks.
The shelter hoped to reopen on July 9 but the date could be extended if more staff or animals were infected.
When an animal was brought to the shelter, it was often impossible to tell if it was infected.
The rooms and cat cages at the shelter were being bleached yesterday to try to kill the fungus.
All the cats at the shelter would be dipped in a treatment to kill the fungal spores.
Cats were more susceptible to the disease than dogs, and no dogs at the shelter had been diagnosed with ringworm.
However, the dog centre would remain closed as a precaution.
SPCA Otago has launched a $1.5 million fundraising campaign this week to give its rundown Dunedin animal shelter a facelift.
Dr Beattie said a new centre, with easier-to-clean surfaces, would make it easier to control viruses and diseases, such as ringworm.
