Can dogs with Bordetella or kennel cough spread their disease to cats or people?

Question: 

Various questions on Bordetella and coughing cats: If a dog has kennel cough, do you suspect Bordetella? Should sick dogs be kept away from sick cats in a shelters? What is the risk that cats in the household may get sick if a new shelter dog with kennel cough is brought into the household? How about the risk of Bordetella infected cats for immune-suppressed people?

Answer: 

Like feline URI, kennel cough is a multi-factorial disease. Bordetella is most common, but other pathogens include canine parainfluenza, canine herpes, sometimes canine distemper, perhaps mycoplasma, canine influenza these days, plus stress, crowding, poor air quality etc. Two things that make kennel cough slightly more manage-able in a shelter are that Bordetella is at least somewhat treatable with antibiotics, and there is no stress-activated common carrier state for the canine pathogens, as there is for herpes in cats. In a shelters, sick cats and dogs should definitely be kept separate. There is a risk that the dogs coughing can make the cats sick (and miserably stressed – studies show barking dogs are one of the biggest stressors for confined cats, and the effect is even worse when they are sick). But there is also a risk that coughing dogs will give cats subclinical infections, which they can then pass along to other dogs! This can happen with some strains of canine parvovirus as well. The risk of a sick or recently recovered dog infecting a cat in a home, on the other hand, is very low. Although it has been reported at least once (disease in two Siamese cats following adoption of a shelter dog with kennel cough) in my experience it is very uncommon. In fact, it is surprisingly uncommon for coughing or recently recovered dogs to transmit kennel cough even to other dogs in a home, even though we know that people usually don’t comply with our sound advice to keep the animals separate for a quarantine period. Virtually all pathogens of kennel cough and feline URI can be found in normal, healthy animals showing no signs of disease. Very often it takes stress, high density housing leading to huge doses of infectious agent, and multiple simultaneous infections to see the kind of serious illness we find in shelter animals. That’s why even though most recovered cats are still shedding herpes or calici at the time of adoption, it is fairly uncommon for the resident cats to become ill (and when they do, as often as not, it is likely a re-activation of their own herpes infection, rather than transmission of a new virus or bacteria). To my knowledge, there have been no reports of human Bordetella infection from cats, although many cats can be asymptomatic carriers. (There has been a report of human infection from a rabbit.) Still, always good advice for immune suppressed people to adopt healthy animals and keep them that way through vaccination and deworming and prompt treatment of illness. Coughing cats: other causes of coughing in cats include herpes infection (not that uncommon!), lungworm (also not that uncommon!) and non-infectious causes such as asthma, foreign body and heart failure/cardiac enlargement. Individual coughing cats should always be worked up with radiographs if resources permit, as some of the underlying causes of coughing cats can be serious.