Sunday, October 9, 2016

Will laboratories in the future employ Labradors?

Labrador, lab test, dog sniffing diagnosis, canine olfaction, UTI
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?”

Labrador, old dog, senior dog, UTI, canine olfaction
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?

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/ofw051