Some people like to send me links to internet sites to see if they can get a rise out of me. There are a few usual suspects (both senders of information and places I get sent to) but a new one for me was tlcpetfood.com
For some reason, this site has a series of FAQ's completely unrelated to pet food. Some are rather bizarre, such as "My dog keeps getting pneumonia, and we just found out her internal organs are on the wrong side. Help? "
Many of the answers are fine. That's because they're plagiarized... verbatim text taken from reputable sites (mainly AAHA's Healthy Pet site) without attribution. Besides the whole violation of intellectual property aspect, it's at least good that the advice is sound.
Some of the other answers they provide (likely the ones that aren't plagiarized) are considerably less sound.
The one that got sent to me was "Is it okay for my dog to lick my son's face?"
This is actually a common question and a reasonable one. There's no perfect answer to it, but there are definitely some imperfect answers, such as this one:
(It starts out okay...)
Yes, it probably is.
- I'd agree with that statement.
(Then goes downhill quickly...)
The only disease that dogs and humans can pass back and forth through saliva is beta strep throat, which is relatively rare.
- This is a myth that just won't go away. There's no evidence that pets are relevant sources of strep throat. Furthermore, there are many other pathogens that can be transmitted from dogs' saliva to people. Disease isn't common but it does occur and it can be fatal in some situations.
And if your son has a weakened immune system, you may want to be careful about exposing him to the normal bacteria that's present in the saliva of healthy dogs.
- Good advice. (However, if their statement that strep is the only thing that can come from dogs was actually true, this one wouldn't make any sense.)
My response to this common question is that I don't particularly like being licked by my dog. It's a personal thing and not a germaphobic response. It's unlikely to harm me as an adult with a (hopefully) functional immune system. I don't hover around my kid to make sure they don't get licked, but I don't encourage it either.
Licks to young kids (especially around the face), licks that have contact with skin lesions or mucous membranes (e.g. mouth, nose) or licks to people with compromised immune systems (including people that do not have a functioning spleen) are higher risk. Strep throat isn't a concern, but many other things are. There's a cost-benefit. If it's an important part of someone's bond with his/her animal, that's fine. Individuals just need to understand the risks, and be aware of when the risks are higher. Part of that is getting good advice, which can be a challenge on the internet.
An upcoming article in the journal Emerging Infectious Diseases entitled "Zoonoses in the bedroom" has attracted some attention in the press. I haven't been able to access a copy yet, but will probably write about it soon. However, one article that was written about the paper had a pretty weak lead-in piece:
"Nikki Moustaki knew something was wrong when she got strep throat for the sixth time in a year. Her doctor wanted to take out her tonsils. But Moustaki, an otherwise healthy 30-something, was determined to uncover the source of the infection. "I saw a bunch of specialists, and one suggested my dog might be a carrier," said Moustaki, a New York City-based dog expert and trainer. "I had never thought of that. When you think of contagious diseases in dogs you think of rabies and ringworm, you don't think of strep." After four walks a day on the streets of Hell's Kitchen, Moustaki's dogs -- a schnauzer called Pepper and Ozzie, a schnoodle -- would curl up beside her in bed. Following her doctor's surprising suggestion, Moustaki started cleaning Pepper and Ozzie's paws with baby wipes after each walk. And she's been strep-free ever since."
While it's good to see the potential role of pets in human disease considered (since it's often overlooked), this is a example of the opposite end of the spectrum: implicating pets with absolutely no evidence, and actually, contrary to all available evidence. Saying that cleaning her dogs' feet prevented her from getting strep throat makes little sense on many levels. Firstly, if it actually made the difference, then she wasn't really getting strep from the dogs, it was coming into the house on the dogs' feet from the ground outside. There's no evidence the outdoor environment is a relevant source of strep. If strep was present on the dogs' feet, it would have to make it to her nose and mouth, and that degree of contact is hopefully unlikely (and if present, it would be associated with a lot bigger concerns that strep). Further, despite various studies, there is no evidence that dogs are even rare reservoirs of Group A Streptococcus, the cause of strep throat. Recurrent strep throat in people is caused by repeated exposure to infected people.
Like I said, it's good to see recognition of the potential role of pets. The next step, however, has to be looking for the evidence. It's not hard to find a few good references that talk about the role (or lack thereof in this case) of pets in human strep infections. Implicating the pet and recommending a rather bizarre foot hygiene regimen isn't really helping anyone.
Is it just coincidence that the infections have stopped in this woman? Probably. Recurrent infections don't tend to go on forever. However, maybe her increased attention to cleaning her dogs' paws also led to her paying more attention (consciously or otherwise) to her own hygiene practices, which would have probably played a greater role in disease prevention.
I was asked this the other day, in regards to a post about pets and recurrent strep infections in people: "You listed a few things to remember and one of them was how the pet might be an "innocent bystander infected by a family member." Is there any indication that a dog might get sick from licking a person infected with Group A Strep?"
Streptococcal infections in dogs are very rare. When they occur, they are typically caused by Streptococcus canis, a Group G strep. Group B strep infections have also been reported. I'm not aware of any reports of Group A (Streptococcus pyogenes) infections in dogs, despite the fact that exposure is probably very common.
Group A strep is a predominantly, if not exclusively, human pathogen. It can be found in healthy individuals (e.g. in the throats of 10-15% of healthy kids) and is the main cause of strep throat. Group A strep also causes invasive infections such as cellulitis, various soft tissue infections, and in rare circumstances, necrotizing fasciitis (flesh-eating disease). Considering how commonly healthy people carry this bacterium and how common strep throat is, you have to assume that dogs are frequently exposed to this bacterium from household contacts.
Licking a healthy human carrier would certainly create an opportunity for a dog to be exposed. Licking wounds of patients with strep infections would probably be worse. Since exposure is probably common and we don't really identify problems in dogs with this bacterium, the risk of infection in dogs is presumably very low. However, basic measures should always be used to reduce the risk of exposure to infectious agents. Even though we don't recognize Group A strep as a problem in dogs, you don't want your dog to be the first case. Dogs shouldn't be allowed to lick infected wounds for both the health of the dog and the person. Strict avoidance of people with strep throat doesn't make sense, but licking should perhaps be avoided since the sick person could also be at higher risk for a secondary infection from the multitude of bacteria present in the dog's mouth.
Bottom line... the risk of Group A strep infection in dogs is minimal, but basic hygiene practices can make the risks even lower.
My wife has a lousy immune system. She's a good indicator of whatever infectious diseases are circulating in the region. After running through a stretch where our whole family was biohazardous (baby with a cold, older two with two different bugs that they then spread to each other), Heather developed strep throat. This common bacterial disease is caused by Group A Streptococcus. I've previously posted about issues regarding strep throat and pets, and the fact that there is little evidence supporting pets as sources of strep throat in households. However, I still get asked about this, and I still see recommendations on the internet to test or even treat pets to try to contain strep throat in a household (for example, see these posts on medhelp.org and justanswer.com).
As a veterinary infectious disease specialist who runs a microbiology research lab (and someone who likes to play around and look for strange things), I'm in a perfect position to start culturing my pets to look for a link, but I don't bother. We've not found any convincing evidence, and neither have other groups, that pets are a source of strep throat for humans. There are a number of zoonotic disease concerns involving household pets, many of which dont' receive adequate attention, but this isn't one of them. More information about "Pets and Strep Throat" can be found in the previous Worms & Germs post of the same name.
Strep throat is caused by Group A Streptococcus, a bacterium that can be found in the throat and on the skin of some healthy people. Strep throat and impetigo are the most common diseases caused by Group A Streptococcus, although severe (‘invasive’) infections can occur, including ‘flesh-eating disease’. Group A Streptococcus is typically spread between people, both from people that are sick and healthy carriers.
Group A Streptococcus carriage by dogs and cats is extremely rare, and it is unlikely that they are involved in transmission to people. There were some older studies implicating dogs in transmission of Group A Strep, however there were weaknesses in the methods used by those studies which probably lead them to misidentify other types of Streptococcus that are often found in dogs as Group A Streptococcus. There is currently no convincing evidence that pets are a source of strep throat infection, although the possibility cannot be completed dismissed.
I have had questions about treatment of pets when recurrent strep throat infections were present in a household, which is not supported by any evidence and could lead to problems like antibiotic resistance and side-effects from antibiotic use such as diarrhea. It’s hard to say whether there is any indication to test dogs or cats when recurrent strep throat is present in a household. Collection of a throat swab by a veterinarian and culture of the swab is fairly easy to do. It’s not unreasonable to consider that but a few things must be remembered:
- Even if Group A Streptococcus is found in a pet, it does not mean that the pet is spreading it. The pet might just be an ‘innocent bystander’ that was infected by a family member. It makes no sense to test the pet if the rest of the household is not being tested.
- Proper identification must be performed by the laboratory to differentiate Group A Strep from other strep. Just finding ‘Streptococcus’ is not useful.
- There are no guidelines for what to do in the unlikely event that a pet is identified as a carrier.
Overall, pets are not likely a major (or even minor) source of strep throat. If strep throat is circulating within a household, it's most likely being spread between people.