Dogs have a particularly tough time surviving the harsh winters of winter in Australia, with temperatures dropping below -30C (46F).
But despite their best efforts, they can be killed by a rare and potentially fatal bacterial infection called canine pneumonia.
The bacteria, called C. pneumoniae, is present in dogs but it can also be found in cats, pigs and other wild animals, and the main risk for human infection is exposure.
So why do some dogs get it?
The causes are still unclear, but the most likely ones are a combination of the weather, climate and human behaviour.
If left untreated, C. pandemic could lead to severe illness, death or permanent disability, with some experts suggesting it could kill as many as 10,000 people a year.
One theory is that dogs could become infected with C. pulmonary syndrome, which causes chronic cough, shortness of breath and shortness or paralysis of the lungs.
This is due to a mutation in the DNA of the bacteria that causes the disease, and it affects the immune system.
Dogs can also become infected through handling contaminated food or surfaces that have been infected by bacteria that live in the environment.
However, it’s not clear whether C.P.S. has a direct effect on human health.
“It’s hard to know what the exact relationship is between C. P.S., C. respiratory syndrome, and C. lung,” Dr Henningsen said.
The main risk, she said, was for dogs to become infected in contact with cats and cats living in a human’s house.
However the condition is not contagious in humans, and if the infection is left untreated the animal will recover.
The virus is found in animals and the Australian Government has advised pet owners to keep their pets in covered outdoor areas.
Dogs have the highest risk of contracting C. infection.
The most common risk factors for C. pneumophila infection are people who have been exposed to dog poo or who have recently been exposed.
“We don’t know what to do to prevent the spread of this disease, because the people that are affected have not been exposed,” Dr Sjodin said.
Dr Sjoerd van Lierop said it was difficult to say how many dogs were affected.
“The disease is not spreading very well in Australia at the moment, but we are working on that,” he said.
“As soon as we have the data we will be able to say that.”
The Australian Government is offering vaccination programs for dogs and cats, and said a vaccine could be available within six weeks.
Dogs infected with canine pneumonia are usually very ill, with symptoms including cough, fever and weakness.
“If you are not immunised you are very likely to develop pneumonia and that is very bad news,” Dr van Liersop said.
There is no vaccine currently available, but vets recommend vaccination against C. disease.
Dogs also tend to be the first to contract the bacteria and so are particularly vulnerable to the disease.
If you or someone you know has been exposed, it is important to be tested.
If your pet has C. cough, respiratory illness or pneumonia, contact your veterinarian and let them know.
They may be able take a sample for a blood test to confirm if you or your pet is at risk.