The Pennsylvania SPCA has placed two of their shelters on lockdown after several canine deaths.
Signs stating the facility would be "closed until further notice" greeted people stopping by the shelters located at 350 Erie Avenue and 111 Hunting Park Avenue in Philadelphia Monday.
Six dogs died since last Wednesday after they came down with a severe illness – possibly canine influenza. Four of the canines were euthanized.
"In this particular case, the onset is very quick going from healthy to sick in a short amount of time, to the point where they have respiratory distress and potentially could die," PSCPA veterinarian Dr. Rachel Lee told NBC10's Denise Nakano.
Symptoms of the disease include cough, runny nose and fever with severe cases causing dogs to bleed from the mouth and nose.
Shelter employees wore masks and gowns as they sanitized the main facility on Hunting Park Avenue hoping to keep hundreds of dogs from catching the virus.
Blood samples taken from the infected dogs were sent to a laboratory for testing with results expected by Thursday.
Until then, officials said people could still provide a foster home for PSPCA canines as long as they do not have any other dogs in their home.