Prince George’s County Animal Shelter in Maryland has halted all dog adoptions temporarily as workers respond to an illness.

On Tuesday, the shelter said all dog adoptions are on hold until further notice while they treat the dogs that are ill at the shelter and try to stop the spread of the disease.

It isn’t known what the illness is or what caused it, the shelter said in a Facebook post.

“As we continue to see overcrowding in our shelter we are seeing an uptick of disease, as are other shelters nationwide, and we are acting quickly to help stop the spread of this disease,” said David Fisher, associate director of the department of animal services, in a statement.

Dogs will be allowed to leave the shelter if they are returned to their owner. For dogs that aren’t showing signs of illness, adoptions in progress can go forward — or they could be fostered.

The shelter said it is encouraging pet owners to avoid communal water bowls for their pets, keep their dogs’ vaccines up to date and take them to a vet if they have signs of a cough or runny nose.