A Dog’s Fur Contains Fewer Harmful Germs than a Man’s Beard by Stanley Coren

Dogs shed fewer microbes during medical scanning than do bearded men.

When it comes to modern medical practice it has become routine to require an MRI scan when dealing with neurological disorders, especially those affecting the brain or spinal cord. This is not a problem if you are a human since such scanners are becoming more common; however, if the patient is a dog the situation is more limited. To my knowledge there are very few veterinary clinics equipped with dedicated animal scanners. The major reason is the cost. Such large expensive pieces of equipment in hospitals are usually subsidized by government funds, while for veterinary purposes the cost must ultimately be borne by the pet owners. At a practical level this places such diagnostic equipment out of reach except in rare instances.

However, in more developed countries veterinarians have been discussing ways to get these valuable diagnostic images when there are simply not enough MRI scanners available for animal use. One of the solutions that is often offered starts with the fact that many human MRI scanners are underutilised or are vacant for a number of hours each day. What about making such scanners available for animal imaging during such downtimes?

Unfortunately, hospitals and private imaging clinics have been very sceptical about offering their MRI units for veterinary use. One of the main concerns has to do with hygiene. There is a real fear that people will be exposed to zoonotic diseases (these are diseases which are transmitted from animals to humans) if they share diagnostic scanners — even if the apparatus is cleaned and disinfected after each animal use. However, up to now there has been no scientific data to support, or deny, the validity of such fears.

A new study has just appeared which provides some interesting data suggesting that it is just as safe to share an MRI unit with a dog as it is to share that MRI with a bearded human. The study team was headed by Andreas Gutzeit, of Switzerland’s Hirslanden Clinic. The rationale for using bearded men as the comparison for dogs was not an example of pogonophobia (which is an irrational fear of beards). The team of researchers seems to have reasoned that because microbes carried by dogs are apt to be hidden in their fur, the only fair comparison would be to search a hairy section of human anatomy for similar bacteria. Obviously, an alternative choice could have been head hair of both men and women.

The researchers took swabs from the beards of 18 men (aged 18 to 76) and from the neck fur of 30 dogs of various breeds. The density of microbes that they found was then assessed. All of the men had high microbial counts while only 77% of the dogs showed a similar high microbial presence. More important was the fact that the potential pathological impact of the microbes carried by the humans was greater. These investigators found that 39% of the humans had pathogenic bacteria in their beards as contrasted to only 13% of the dogs in their fur.

In addition, the researchers took swabs from the mouths of both the men and the dogs and their conclusion is “There were significantly more microbes present in the oral cavities of the human subjects than in the oral cavities of the canine subjects”.

The research team noted a secondary benefit of allowing the MRI units to be used for diagnostic scanning of dogs. This is because following each canine scan the imaging unit was wiped down with a disinfectant and in the end, it was found to have a lower microbial count than the units which were exclusively used for humans because these are typically not disinfected as frequently.

Ultimately the researchers summarise their research findings saying that

“In this study men have a significantly higher bacterial load in their beards than dogs have in their fur. More human-pathogenic bacteria were found in the men’s beard than in the dogs’ fur…. No micro-organisms causing zoonotic diseases could be detected in the environmental probes sampled in the MRI scanners after the canine exams. On the basis of these findings, dogs can be considered as ‘clean’ compared with bearded men.”

I personally would hope that the results of this study might cause hospitals for humans, as well as private MRI scanning facilities, to consider the possibility of making their imaging devices available for veterinary use during off times. But sadly, knowing the irrational fear that some segments of the population have about the possibility of disease transmission from animals, combined with the litigious nature of today’s society, I fear that access to these valuable diagnostic tools will still be limited when it comes to our pet dogs. Perhaps, with luck, my pessimism will be proven wrong.

With thanks to Stanley Coren

References and Links:

Andreas Gutzeit, Frank Steffen, Juri Gutzeit, Junus Gutzeit, Sebastian Kos, Stephan Pfister, Livia Berlinger, Matthias Anderegg, Carolin Reischauer, Ilona Funke, Johannes M. Froehlich, Dow-Mu Koh, Christina Orasch (2019). Would it be safe to have a dog in the MRI scanner before your own examination? A multicenter study to establish hygiene facts related to dogs and men. European Radiology, 29, 527–534.

Would it be safe to have a dog in the MRI?

Stanley Coren PhD., DSc, FRSC

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