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It started when two canine scientists decide to become pen pals in an era of digital media...


26 September 2014

Cat and Dogs: seeking solutions with sniffing canines and science

Hi Mia and Julie, 

First of all, I LOVE your blog! 

After meeting at SPARCS this past summer (summer for us in North America.. I take it summer is just beginning in Australia!), I’ve followed it closely. 

You do amazing things for the promotion of  canine science. Serious love.

A bit of background for the readers: I’m currently doing my PhD at Dalhousie University in Halifax, Nova Scotia in Canada, under the supervision of Dr. Simon Gadbois

Dr. Gadbois has an amazing amount of knowledge and experience in the science of sniffing (just check out Gadbois & Reeve, 2014 link below!). 

He’s trained sniffer dogs for the conservation of ribbon snakes and wood turtles, to track coyotes, and to detect invasive pests in lumber. He and I have taken on a different type of project and are studying the intricacies of biomedical detection dogs, specifically, the very interesting phenomenon of Diabetic Alert Dogs

Cat Reeve at #SPARCS2014 where she won the 'Best Emerging Researcher' prize

I say interesting because there’s anecdotal evidence suggesting that some dogs alert their owners to hypoglycemic events (low blood sugar). In 2008, Deborah Wells published a series of case studies where dogs were reported as signalling (barking, licking, pawing etc. the individual) while their owners were awake, while they were sleeping, and even when their owners were in a different room with the door closed! And this is with no previous training! 

Isn’t this fantastic! Severe hypoglycemic events can be extremely dangerous for individuals with diabetes. If not treated, they can lead to seizures, comas, and even death. The fact that dogs may be able to alert an individual before a serious hypoglycemic event means less worry about hypoglycaemia unawareness, and blood sugar dropping over night when individuals are unconscious.

Given that dogs are signalling through closed doors, it is assumed that the dogs smell something that alerts them to a change in the physiology of their owner (as opposed to behavioural cues, as is believed to be the case with seizure alert dogs). There are many companies that have taken advantage of this supposed ability, and have trained Diabetic Alert Dogs (DADs) to sell to individuals with diabetes. 

In my own searches, I have found no company that publicly provides information as to how they train their dogs. However, according to recent studies (see Gonder-Frederick et al., 2013 and Rooney et al., 2011 below) these trained DADs dogs contribute greatly to the families of individuals’ with diabetes; they signal consistently and, consequently, significantly reduce the number of hypoglycemic events an individual experiences. 

Now, if it is in fact an olfactory cue that dogs use to identify a drop in blood sugar in their owners, one would expect that if you presented one of these trained DADs with the “scent” of hypoglycemia without the individual present (just like having the owner with diabetes on the other side of a door), the dog would still signal. 

Dehlinger and colleagues recently tested three DADs in a lab setting, presenting the dogs with human biological samples that were obtained identically to the way the samples used to train the dogs were obtained. In this study, none of the three dogs could pick out a hypoglycemic sample from a normoglycemic sample! DARN!

So what is it that these dogs smell? How is it that some DADs are accurate at signalling hypoglycaemia but evidently cannot signal in the lab? 

Enter ME! This is what I’m trying to figure out!

One possibility is that, at least in the study outlined above, the use of sweat samples was misguided. Maybe the volatiles are more strongly present in an individual’s breath. I am currently in the process of testing whether there is one channel more likely than others to expel the volatiles needed to detect a change in blood sugar, i.e. breath, sweat, or saliva. 

So far we’ve found that, after being trained to detect extremely low saliency scents, our dogs can detect and discriminate between human breath samples with incredible ease and accuracy (see the video of Koda discriminating between breath samples). 

Little Koda discriminating between breath samples. The jar that has the check mark on it is the target sample. The jar with the x+ is a different breath sample. When Koda first enters the room, he smells a jar that is the “sample” (it matches the target sample)... This is the smell we want him to find amongst the three jars that are closer to the camera. He chooses the right one!

Preliminary tests with patient samples suggest that our dogs can also tell the difference between breath samples taken from the same individual when their blood sugar was low, when it was normal, and when it was high (unpublished). 

Also, it’s possible that in the Dehlinger et al. (2013) study, the sample collection procedure was simply not sufficient enough to contain the volatiles produced during a hypoglycemic event. With the help of a fantastic chemist at Dalhousie (Dr. Peter Wentzell), we have perfected a procedure that coats cotton balls in silicone oil. This is believed to help contain the volatiles through the *magic of chemistry.  

*may actually be science, not magic - check with the chemists

Another potential is that these DADs are simply responding to a general stress response in the body. It’s possible that DADs (and untrained dogs who signal to their owners) are picking up on the physiological change associated with stress (changes in cortisol, adrenaline etc.). Kind of how people say animals can smell when you’re scared. 

If this is truly what’s happening, you would expect to see DADs giving a lot of false alarms. 

And in fact, personal communication with friends of friends who own DADs tell me that their DADs alert to not only hypoglycemic events, but to asthma attacks, anxiety attacks, etc. If you read carefully, few studies ask owners of DADs if their dog gives a lot of false alarm signals (dog signals to their owner and after the owner checks their blood sugar, they discover that they are not low). 

Isn’t this fascinating? 

The dogs I work with are incredible (shout out to the amazing owners that let me work with their dogs every week), and have incredible work ethic and sniffers. 

Our dogs are extremely motivated to work (because we make it super fun!). This is Nutella on her “break”. She doesn’t want a break. She wants to keep working! She’s whining and pawing at the door of the work room.

With the assistance of these amazing dogs, hopefully Dr. Gadbois and myself will be able to shed light on how exactly DADs do their job in the near future - I'll let you know how we go!

Cat Reeve
PhD Candidate
Dalhousie University

Follow Cat on Twitter

Follow the Dalhousie Canid Behaviour Research Team on Facebook

Check out #DogsOfDal on Instagram

Further reading:

Brown S.W. & Strong V. (2001). The use of seizure-alert dogs, Seizure, 10 (1) 39-41. DOI: 

Dehlinger, K., Tarnowski, K., House, J.L., Los, E., Hanavan, K., Bustamante, B., Ahmann, A.J., & Ward, W.K. (2013). Can trained dogs detect a hypoglycemic scent in patients with Type 1 Diabetes? Diabetes Care (Observations), 36, 98-99. 

Fier, B.M. (2004). Morbidity of hypoglycaemia in type 1 diabetes. Diabetes Research and Clinical Practice, 65, 47-52. 

Gadbois, S., & Reeve, C. (2014). Canine Olfaction: Scent, Sign and Situation. In A.  Horowitz (ed.). Domestic Dog Cognition and Behavior. New York: Springer. 

Gonder-Frederick L., D. Warren, K. Vajda & J. Shepard (2013). Diabetic Alert Dogs: A Preliminary Survey of Current Users, Diabetes Care, 36 (4) e47-e47. DOI:  

Rooney N.J., Morant, S. & Guest, C. (2013). Investigation into the Value of Trained Glycaemia Alert Dogs to Clients with Type I Diabetes, PLoS ONE, 8 (8) e69921. DOI:

Matyka K.A. (2002). Sweet dreams? - nocturnal hypoglycemia in children with type 1 diabetes, Pediatric Diabetes, 3 (2) 74-81. DOI:   

Wells D.L., Lawson S.W. & Siriwardena A.N. Canine responses to hypoglycemia in patients with type 1 diabetes., Journal of alternative and complementary medicine (New York, N.Y.), PMID:

© Cat Reeve | Do You Believe in Dog? 2014

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