If you're a dog owner, heads up:

A mysterious and potentially fatal respiratory illness in dogs has been reported in several states across the country, as veterinarians continue to search for what may be causing the condition that has killed some dogs.

The illness starts out as a cough that can last for several weeks, but it may not respond to antibiotics, which can leave the dog struggling to breathe and with severe pneumonia.

Veterinarian Lindsey Ganzer told Today that the virus "seems to happen very, very quickly — to go from this cough that's just won't go away ... and then all of a sudden they develop this pneumonia."

The Colorado-based vet said she "has seen close to 30 dogs with the condition since the middle of October." Cases have been reported in Oregon, Florida, California, and elsewhere.

The Oregon Department of Agriculture said in a press release that pooches with this illness "do not test positive for any of the common causes of respiratory illness."

Nobody's really sure what it is, in other words.

Last August, at least 30 dogs in Michigan died from another mystery illness, so apparently this is more common than you'd think.

Still, if this gets worse, I'm keeping an eye on those guys who love things like gain-of-function research!

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