What to make of medical dogs

For thousands of years we have guided the evolution of dogs to fulfill our needs for work and companionship.  Service dogs are pretty remarkable.  I love to watch herd dogs mimicking the dance of predator and prey.  When you see a guide dog help someone navigate a building or street, you can’t help but to be impressed by the dogs “devotion” and “skill”.

It seems there is a new canine skill in the news every day.  Now, in addition to the traditional roles guiding the blind and deaf and helping the physically disabled, dogs are claimed to be able to calm autistic children, detect blood pressure changes and seizures, and find cancers. Dogs have been used in the bed bug epidemic to find the critters (with little scientific evidence of success).

Humans and dogs have co-evolved successfully to create strong owner-dog attachments (to the point of pit bull owners defending their dogs rather than acknowledging a dog’s danger to humans).  It seems intuitive, and is quite plausible, that dogs can calm us, can help lead us in ways analogous to their roles in nature (if “natural” can even be applied to dogs). It’s easy to see how herding behavior can be adapted into guide dog behavior, or hunting behavior into chemical detection.

What’s less clear is whether any of these roles are based on fact rather than intuition.

What raised my interest this week was a dog featured on ABC News. The show followed a young woman with a “rare heart condition” that goes unnamed.  It shows her dog alerting her to an impending fainting spell. The film itself is useless as data—it simply shows the dog nudging the patient and the patient responding by lying down. But even assuming that the family has seen “successful” alerts of fainting, there is no evidence in the literature to suggest dogs can actually do this in any context.  It is likely that the dog improves the woman’s sense of security and well-being (something the literature supports in human-service dog relationships) but there is no way to know if the dog is “sensing” changes in blood pressure as claimed.

One of the most interesting medical claims for dogs is an ability to detect cancers in humans, perhaps before conventional testing might. While anecdotes abound, there is scant literature to support this ability. One unimpressive pilot study looked at dogs’ potential ability to detect bladder cancers from urine samples. The idea behind cancer dogs is that there may be volatile compounds produced in cancer patients that dogs can detect by scent.  In these studies, the compounds are not identified, not tested for, not named. There are many confounders, for example, in the few samples used, there may be other differences being detected by the dogs.

In the other study (I found very few) dogs were “trained” to detect lung and breast cancers in humans. The methodology of breath sampling is not validated as far as I can see, and once again, the putative compounds in breath are not identified. Statistically, the efficacy is marginal at best.

Another controversial use medical use of dogs is for seizure detection. So-called “seizure alert dogs” are purported to warn their masters of impending seizures, and to stay with them during the event.  It doesn’t take a bucket of skepticism to wonder what this actually means.  Many seizures are preceded by marked changes in behavior as the patient experiences an aura, something anyone/anydog should be able to notice. Staying by a bonded human isn’t too unusual either. I do wonder how the humans know what the dog does, as many true seizures are accompanied by a period of confusion and memory loss. An objective witness would be needed to note the behavior.

And some case studies have done just that. There aren’t a lot of data, but one patient monitored in a seizure unit experienced nine seizures, one of which was “sensed” by her dog.  In another, the dog sensed a “pseudo-seizure”, that is a fit that is not, neurologically-speaking, a seizure but a non-seizure set of behaviors, often precipitated by stress.

That dogs can be trained to help humans is pretty clear—we’ve bred them for this.  But these abilities must necessarily have limits, limits set by biology. If a behavior seems implausible, the evidence for it must (from a Bayesian standpoint) be pretty damned solid.

I don’t doubt the social and emotional value of dogs as companions, and as active helpers in many circumstances. But beyond this, the evidence is wanting.


Allen K, Shykoff BE, & Izzo JL Jr (2001). Pet ownership, but not ace inhibitor therapy, blunts home blood pressure responses to mental stress. Hypertension, 38 (4), 815-20 PMID: 11641292

Lane, D., McNicholas, J., & Collis, G. (1998). Dogs for the disabled: benefits to recipients and welfare of the dog Applied Animal Behaviour Science, 59 (1-3), 49-60 DOI: 10.1016/S0168-1591(98)00120-8

Willis, C. (2004). Olfactory detection of human bladder cancer by dogs: proof of principle study BMJ, 329 (7468) DOI: 10.1136/bmj.329.7468.712

McCulloch, M. (2006). Diagnostic Accuracy of Canine Scent Detection in Early- and Late-Stage Lung and Breast Cancers Integrative Cancer Therapies, 5 (1), 30-39 DOI: 10.1177/1534735405285096

Dalziel DJ, Uthman BM, Mcgorray SP, & Reep RL (2003). Seizure-alert dogs: a review and preliminary study. Seizure : the journal of the British Epilepsy Association, 12 (2), 115-20 PMID: 12566236

Strong V, Brown S, Huyton M, & Coyle H (2002). Effect of trained Seizure Alert Dogs on frequency of tonic-clonic seizures. Seizure : the journal of the British Epilepsy Association, 11 (6), 402-5 PMID: 12160671

Doherty, M., & Haltiner, A. (2007). Wag the dog: Skepticism on seizure alert canines Neurology, 68 (4), 309-309 DOI: 10.1212/01.wnl.0000252369.82956.a3


  1. DrugMonkey

     /  May 25, 2012

    One thing you are missing is that training for detection would be entirely possible, if we knew the right stimuli. That’s really the breakdown here…we don’t know if there’s anything there for a dog to detect when it comes to cancer.

    • Thanks, Skinner. Next you’re gonna tell me pit bulls are really sweet with all the right stimuli.

      • It would depend on there actually being a stimulus.

        I would actually believe in a sweet pit bull more than one that can predict a seizure or cancer. Just because my family has a history of raising wild dogs, most of which were really good with kids. But none of them could predict a seizure or cancer.

  2. You misspelled Bayesian … Not a good sign

    • pedant

      • Yeah, now, if it were funny, I would. For instance, when someone confuses “insipient” with “incipient”. I think my verbal SAT even had a question about that.

  3. A civilian’s view: there may be a few cases of actual help, but most people want an excuse to a) be special and b) get their dog into any darn place they please. I work in a big box store where the door person is forbidden to question any dog’s purpose,though there is signage (and law) that only service dogs are allowed in. I see easily 10 dogs a day,with maybe one wearing service dog ID. As a food server, I am disgusted, but not surprised.

  4. Ron Litman

     /  May 25, 2012

    Nice post today. I’m a pediatric anesthesiologist – just the other day an autistic patient of mine showed up with her support dog, and the only way I could calm her was to “allow” her dog to push the propofol.

  5. You made a very brief mention of pitbulls, and I’d just like to say that I volunteer at the local animal shelter, and I don’t feel pitbulls are inherently bad dogs (although I admit that “volunteering at the animal shelter” doesn’t make my opinion valid).
    It’s true that pitbull breeds were originally selected for dogfighting, but that hasn’t been the case for a long while and most pitbulls are loving, if energetic, pets.

    Also, could I please ask you to write something about compression-only CPR? All of my instructors seem to think that the American Heart Association is remiss to not adopt it as the principle form of CPR. But all of my instructors aren’t doctors. My most qualified teacher to date was an RN, but she made little to no commentary on the subject.

    And trigger points. I’d love to have a clear explanation of trigger points that doesn’t come from someone who moonlights as an acupuncturist. You do requests, right? I would greatly appreciate it..

    • 1) AFAIK, American BLS has changed significantly to emphasize compressions over breathing in most circumstances, about 20:2
      2) evidence for trigger point injection is, AFAIK, not that strong, but has good plausibility and low risk.

  6. Fallsroad

     /  May 27, 2012

    I am mostly a lurker, but this topic is relevant to me. Apologies for length.

    There are two types of seizure dogs I know of: seizure detection dogs, and seizure response dogs. There is some crossover in the training, but most serious service dog organizations will limit their training and claims to the mostly to latter type, not the former.

    Detection, such as it is, can only be trained for if the client has narrow, repetitive, detectable behaviors prior to having a seizure. Dogs are students of human facial and body language, as well as vocalizations. The more consistent the behavior leading to a seizure, the more likely a dog can be trained specifically to it, thus giving the appearance of magical “detection” abilities on the part of the dog. There is a widespread belief that dogs can smell pheromonal or other changes in their humans before a seizure, but as far as I know none of this is in any way proven to be true. The behavioral detection and response, on the other hand, is a known quantity, and for those seizure patients for whom such behaviors are very consistent and accompany most or all of their seizures, a detection dog can be very useful. Having a grand mal seizure while lying on your bed after being alerted is infinitely preferable to having one while standing up.

    I have a seizure response dog, a golden retriever professionally trained to respond specifically to my seizure types, which are frequent and medically intractable. He has been with me for seven years. I do not experience auras or have any other warning a seizure is about to begin. It is always a blind side for me. When I have a seizure, he lays on or next to me, or if I am sitting down he stands up, paws on my chest, and vigorously licks my face and any other exposed part of my body until I come around enough to give him a short series of commands to make him stop. Then he lays next to me until I am mobile and clear enough to free him to get up.

    This serves several purposes. My post seizure behavior can include long periods of profound confusion, sleep, and unconsciousness. The confusion is accompanied by intense panic and fear (I have struck people coming out of seizures before, so I am told), so having the dog present forces me to focus on him (gallons of dog spit applied by wet sandpaper has a way of concentrating the mind) and distracts me from said panic and confusion.

    The periods of prolonged sleep or unconsciousness will occur immediately following the end of the seizure, so whatever position I am in at the time is where I remain. This once included, prior to the dog, falling down the stairs during a seizure and remaining asleep/unconscious for nearly 24 hours pressed up against a cinderblock wall with one of my legs trapped painfully underneath me. Needless to say I now live in a one story home.

    With the dog licking me so intently I come out of the post-ictal stupor more quickly, and regain at least enough awareness and focus to find a more appropriate place to wait out the after effects. This has minimized extreme discomfort and injury from staying in awkward positions for lengthy periods of time. It has also served to disrupt some of the mental confusion in the aftermath of a seizure. Given how large a percentage of my waking and sleeping life are given over to seizures and their affects, this is very useful.

    Rufus has his own phone with a nylon loop on it, which he can get for me on command in the event I am physically incapacitated or injured and need to call for help. He knows my wife’s name and will go get her if I ask him to following a seizure.

    Some of this may sound trivial to those who do not experience seizures, but I can tell you the effect of having a seizure response dog has been life altering in the day-to-day . My post seizure experience isn’t nearly as prolonged or as terrible or terrifying as it had been for the 20 years previous to the dog entering my life. It takes a load off my wife’s mind when she is at work, and it keeps me from losing my shit when I have seizures in public. His presence also prevents people from giving me inappropriate medical assistance in public, such as a well intentioned attempts to resuscitate me (I stop breathing near the end of a seizure), or calling 911 and having me pay for an ambulance to the ER (both of these things has happened).

    I am in process to discover of I am a candidate for a temporal lobectomy. Thus far the testing is less than promising, but I have not been ruled out. Pharmacology has nothing to offer me at the moment.

    As for “feeling special” or “just wanting to take my dog anywhere I please,” I’m happy to report that owning and employing a service dog is actually a lot of work. After the dog’s initial raising and training by the organization who did it for me, there came a six month period involving field training so my dog and I become a good public access working team. It was a hair raising experience, being in public with a dog for which I am responsible – making sure he follows his training at every step, leaves people and things alone, and does his response work promptly when I seize. Wherever I go a part of my mind and awareness must be focused on him. Every trip outside the house has to take into account the presence of 80 pounds of dog, so I personally cannot imagine why anyone who didn’t benefit from it in the way I and other service dog partners do would want to have a dog attached to their hip everywhere they go, 24/7.

    At the end of those six months of field training Rufus and I were tested to standards created by Assistance Dogs International – http://www.assistancedogsinternational.org/ – which are in wide use today by training organizations. These standards deal with public access, obedience, and performance of specialized training. It is a fairly rigorous process and must be repeated every two years to retain certification.

    And there is the not insignificant matter of cost. While the raising and training costs were defrayed by the charitable organization and volunteers involved, all of his maintenance and vet care are appropriately on me. In order to retain certification (which is not required by ADA legislation, but it keeps us sharp and helps when we run into problems with access) his vet care has to be consistently up to date. Like any animal under a human’s care there will be unforeseen accidents, illnesses, and so forth, and in order to keep him healthy and able to work, all of those issues must be dealt with promptly. I’m not complaining – every dollar is well spent and worth it, and I’d do all of this even if he were not a working dog, but it is no free ride.

    The study of dog behavior and intelligence has seen a lot of activity in the last ten years or so. Data is beginning to replace myth and supposition. Given how ubiquitous dogs are in human culture this is a positive step, and I hope more work is done in the area of assistance and medical use of dogs, so that appropriate training and application can be determined and public use and access more carefully defined.

    I cannot speak to cancer dogs and some of the other uses brought up in Pals post. I have known people with hearing issues, sight issues, seizures, and in wheelchairs who have benefited from having service dogs. Like any other medical device designed to assist people with illnesses or disabilities their use is limited, and should be appropriate to the person and condition. There is no doubt for me that a properly screened and trained seizure response dog can be extremely useful in mitigating the every day effects of suffering seizures.

    • JA

       /  June 4, 2012

      I have no issues with real service dogs, but I do know people who have an emotional support animal and claim it as a service dog so they can take it places. As a person with allergies, this means that I can not stay at some events, especially if my other environmental allergies are particularly bad. People who have a true service dog are hurt by those who have a fake one.

      • Fallsroad

         /  June 5, 2012

        I’ve read about therapy dogs, but never known anyone who has one. I also don’t know which conditions they are trained for. The use of service dogs has been expanding beyond the more traditionally accepted seeing eye dogs, and I think we as a society still have some things to sort out about their use. That has to begin with whether or not a dog can perform specific tasks that can be considered medically useful.

        I empathize with your allergies. I try as hard as I can to be mindful of other people when I’m out in public with my dog, making sure he isn’t obstructing anyone or impeding their ability to move around a shop, airport, etc, not getting under their feet at dinner, that he is clean and inoffensive and does not seek attention from strangers. The ADI certification requirements address these specific issues.

        There has been a push to train more so-called “hypoallergenic” dogs not only for clients who have allergy issues and can benefit from a dog, but for the wider public who come into contact with them. I don’t know how much of a difference those breeds can make for allergy sufferers.

        • I can imagine a pet helping someone to fight off depression. But ultimately it’s nothing more than an extra loved pet, isn’t it? Not like a service dog, which is crucial to function.
          Reminds me of a guy that waited until all his cats died and then he shot himself in the head behind the bushes of his yard. Not quite the same as what I mentioned.

          • Fallsroad

             /  June 5, 2012

            There has been some work with veterans who suffer from PTSD. I don’t know how scientifically valid that is but it is one area where service dog use is expanding.

            I can see where extreme forms of social anxieties or difficulties might be aided by a dog, but it seems to me it should be a last attempt at a form of treatment, not the first given all that goes along with having and being responsible for an animal.

  7. Fallsroad

     /  May 27, 2012

    I forgot to add something really basic: prior to Rufus I never left the house or went anywhere alone – I always had someone with me. This can be very limiting and a hassle for friends and loved ones. Once Rufus arrived and I felt comfortable with his seizure response capabilities and my ability to handle him in public and rely on him to always respond correctly, I was able to move about on my own, freely.

    That’s kind of a big deal. 🙂

  8. I can’t speak with anything like Fallsroad’s authority obviously (and in any case I’m not sure how useful a data point of 1 is), but yesterday in the ER I saw a seizure dog that was trained to recognize a seizure and go alert someone nearby. This didn’t do much good at the time, since no one had told the residents what the dog was doing none of them could figure out why this random dog was walking up and bumping them with her nose (besides which, the patient was in the hospital already), but it was impressive to watch and seems like the sort of thing that could be useful in a more domestic environment.

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