Dogs in shelters may be susceptible to a severe type of canine pneumonia, because they are stressed by cramped quarters and constant barking. (Steve Fischer/CBC)

Two dogs at the Ottawa Humane Society shelter have died from a rare and severe form of canine pneumonia in the last two months.

Humane society veterinarians said they have never seen this type of disease before. The dogs initially suffer from a cough, lethargy and fever, but the symptoms rapidly progress, with the animals coughing up blood and dying within a day.

The first humane society dog developed symptoms in mid-summer, while the second got sick in early September. Since then, staff have treated every dog with antibiotics, disinfected every pen, and briefly placed a moratorium on adoptions — which was lifted a week ago.

Dr. Shelly Hutchings, a humane society veterinarian, said the illness is caused by bacteria — known as Streptococcus equi — that typically causes mild disease in horses.

In dogs, infection is rare but severe, causing hemorrhagic pneumonia. The disease does not spread to humans.

Hutchings said little is known about how dogs contract the disease, and there is no vaccine to prevent it.

"It's frightening for sure," Hutchings said. "We don't really know what the incubation period is. There's a lot we don't understand about transmission or which dogs it will affect."

Experts believe dogs in shelters may be susceptible because they are stressed by cramped quarters and constant barking.

Bruce Roney, Ottawa Humane Society executive director, said the infections highlight the need for the new shelter, which is slated to open in 2011.

"We don't have proper isolation space in this building," he said. "It makes [diseases] so difficult to control."

Roney said no new cases of the disease have been seen at the shelter, and the pneumonia hasn't shown up in any adopted dogs.

The humane society has asked area veterinarians to watch out for the symptoms.