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| Lachie the Lab may be employed to do Lab tests. Literally. |
Laboratories are typically fairly sterile places to work,
but are they about to get a lot more exciting? According to one study published
earlier this year, laboratory staff may be looking forward to sharing their
space with four-legged colleagues. Indulge me for a second while I
contextualise.
There’s a well-worn veterinary joke that goes something
like this. A man brings a very limp parrot into a veterinary hospital. The
veterinarian auscultates the bird with a stethoscope and pronounces it dead.
The owner says, “Come on? You haven’t even done any tests. You can’t tell me
this parrot is dead. How do we know it’s not African sleeping sickness or
something?”
The vet rolls her eyes and says, “Okay”. She leaves the
room and returns with a cat and a Labrador. The cat jumps on the table, sniffs
the bird, and jumps off.
The dog sniffs the bird and immediately sits.
The vet types away at her keyboard and prints an invoice
for $600. “Your bird is definitely dead,” she says.
“Six hundred bucks??,” the owner cries. “What’s that
about?”
To which the vet replies “I wasn’t going to charge
anything, but what do you expect for a cat scan and a Lab test?”
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| Lachie is not amused either. |
Such a dad joke. And yet it contains a kernel of truth:
the lab test thing is getting real. Not to the extent that it is used on
parrots, but it seems to work on people. In a Hawaiian study, Labradors and
golden retrievers were trained to sit if they detected bacteria in human urine
samples.
Why dogs? Well, they have olfactory acuity 100,000
times stronger than us, and can detect parts per trillion. Dogs are already
used to detect explosives, cadavers and even detecting cancer. It takes around
48 hours to detect bacteria in urine via culture. A dog can do it in seconds.
Plus, unlike most humans, they seem to love sniffing
urine (alas, it is one of Phil’s favourite activities in the world).
The dogs used in this study (n=5) underwent an 8-week
training period, learning to ignore the myriad of odours found in human urine
and only focus on locating samples that had tested positive for bacteria.
Why the focus on urinary tract infections (UTIs)? They’re
super common, especially in patients with neurological conditions such as
spinal cord injury, and the elderly. They can be challenging to diagnose early
in the course of disease, leading to delayed diagnosis and potentially secondary
complications like pyelonephritis. UTIs are the leading reason for
hospitalisation in people with spinal cord injuries, and they are the most
common nosocomial (hospital acquired) infection. If you have a urinary catheter
in hospital, like up to 20 per cent of hospitalised patients, this increases
your risk of a UTI by 5 per cent per day.
The dogs were very good at the task, being able to be
taught to accurately discriminate culture-positive from culture-negative urine
samples. They were able to detect the key offenders – E. Coli, Enterococcus, Klebsiella and Staphylococcus aureus – in concentrated
OR diluted samples.
Why is this a big deal? Well, according to the researchers
who wrote the paper, detecting negative samples quickly will help prevent use
of antimicrobials when they’re not needed. But for patients, detecting UTIs at
an early stage, when less aggressive therapy is needed, may lead to faster
resolution and better outcomes.
There were some limitations of the study. Obviously it
was a small-scale study and the results need to be validated. Still, an overall
sensitivity of 100 per cent and specificity above 90 per cent is impressive.
The researchers took many steps to eliminate confounding factors, for example
all testing was single or double blinded and dogs were trained using samples
from different patients so it could be insured that they had not merely learned
the scent of samples from specific patients. However, while case samples were
only used once in the testing phase, control samples were used throughout each
day of testing so it is possible that dogs might have learned to identify what
was new in the line-up.
Its positive to see us acknowledging and using the skills
of other species in a way that benefits the health of another. But the paper
raises some important questions:
- How do we ensure that dogs (and other species whose
unique sensory apparatus we benefit from) are not exploited? What sort of
working conditions would be needed? Presumably dogs can’t sniff wee all day,
sessions would need to be limited and regular breaks provided for toilet walks
and other activities.
- Could dogs be taught to detect UTIs in other dogs, thereby
benefitting their own species? What about other veterinary patients? Other
disease conditions, e.g. cancer? It would be nice to see the species in
question benefit from their own special skills. (It would also be nice to work
in a multi-species staffed clinic).
- We still rely heavily on culture and sensitivity to
diagnose UTIs – is this now a bit old school? Are there other biomarkers that
could yield a rapid result?
Reference
Maurer M, McCulloch M, Willey AM, Hirsch W & Dewey D
(2016) Detection of bacteriuria by canine olfaction. Open Forum Infectious Diseases doi: 10.1093/ofid/ofw051First published online: March 8, 2016
http://ofid.oxfordjournals.org/content/early/2016/03/08/ofid.ofw051.abstract
