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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.

References

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

Posted in: Science and Medicine

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25 thoughts on “What to make of Medical Dogs

  1. rmgw says:

    Thin evidence indeed – but so is the evidence for all the AAT’s – animal assisted therapies, using dolphins, horse, dogs and everyone else you can think of. Dolphin therapy (see Lori Marino’s research) has a definite downside for the dolphins, and horse-assisted therapy probably does for the equines involved in many cases, too, whilst evidence of therapy in the proper sense of the word taking place over these sessions is vanishingly tiny.

    You’d have thought we got our money’s worth out of nonhuman companions just enjoying the sensation of having improved their lives, or having saved them from an untimely death, an unmatched pleasure for us altruistic humans, surely?

  2. Janet Camp says:

    I’ve come across “therapy” dogs in a couple of situations; one in a hospital waiting room and another at my small business. In both cases, the people claimed that the dogs were essential to their well-being and prevented “anxiety”. It was all so vague, but the outcome is that they are allowed to bring these dogs anywhere (not sure this is true in all states–the incidents I experienced were in Wisconsin and Washington) and in both cases they were more than happy to tell me all about it–at great length.

    The reason I care about this is that I am severely allergic to cats and dogs and remain so even after three years of allergy shots (and ongoing maintenance) that often resulted in severe reactions requiring an EpiPen. I find it somewhat offensive that the (likely untested) value of these dogs is seen as more important than my ability to breathe.

    In the case of my business I was able to simply say I could not accommodate the customer (she understood, but I wonder if she could have sued me for violation of some portion of the ADA?), but with the hospital I had to go to great length to get them to put me in a different room to wait to be called for my lab tests. The woman with the dog could have cared less and was only smug. Only an anecdote, but I think she needed more therapy than any dog could ever provide.

    In both cases, the “therapy” seemed only to involve the person taking great delight in explaining that the dog was allowed anywhere–“just like a seeing-eye dog”. Both were tiny dogs carried in handbags–for whatever that is worth. They seemed to be living security blankets.

  3. DugganSC says:

    One of the girls I dated briefly in Philadelphia was a lawyer at a company that specialized in support animal legal cases. Among their cases was the patient with a support snake (!) who was not allowed to board a plane with her snake draped over her. It’s some pretty crazy stuff and I wouldn’t be surprised in the least if there are people who get them when they don’t need them, just like patients who bully doctors into giving them antibiotics for their colds and drugs to prevent their children from acting up.

    As regards medical testing by animals, I’m reminded of the old joke where a patient, upon asking for additional tests for his condition, got introduced to his doctor’s pets, a cat and a dog. Later that month, he got a bill for two new tests, a cat scan and a lab test.

  4. katwh says:

    This is becoming a hot button issue in the veterinary world. Vets don’t get to decide if a client needs a service animal, or make any determination if that animal is up to the task, so clients often flat out confess their pets are only designated as service animals so they can ride along in the plane cabin or go into restaurants.
    It’s also very difficult to tell which is which at time. That young, healthy looking man may need his service dog to cope with TBI and PTST, and the frail looking older woman may simply want her lab to go everywhere. I’ve seen legitimate, well trained service dogs make a huge difference in the quality of life of clients. A guide dog is like a ticket to freedom for some, and a dog can make a wounded warrior better able to cope with being in public. Those who game the system endanger it for those that need and truly benefit from it.
    Many clinics also give substantial discounts to service animals (the disabled aren’t generally a wealthy bunch). Guide dog organizations have lobbied with some success for these discounts, and vets are generally happy to help. Some clinics have simply stopped advertising, others eliminated the discounts completely and I know of two that now try to determine need in the exam room before offering a discount.
    As for equine assisted therapy, thank heaven it exists for those horses. Many an old, slightly lame but kind horse has found a home there instead of becoming a part of the huge unwanted horse problem.

  5. cervantes says:

    Well, epistemologically speaking, you wouldn’t need to know, or even hypothesize, what volatile compounds the dogs were detecting, if they could demonstrate useful sensitivity and specificity in detecting cancer, or whatever. You could figure that out later. I find that kind of a weak objection. Dogs have incredibly good noses, so it’s not implausible that they could detect diseases.

    I’m not saying existing evidence is any good, just that you don’t need to know the exact mechanism to detect an association.

  6. Bogeymama says:

    I might actually be able to make an intelligent comment for once!

    As a side project, my family became involved in raising guide dog puppies for several years. After raising and training ours (and then having to give him back after 1.5 years :() we stayed on for a few more years taking puppies in so their raisers could have holidays.

    The legalities probably vary from state to state. Here in Canada, it’s a provinical law. Ours started out only covering guide dogs (aka seeing-eye) that were trained by an internationally accredited training facility. Ours were, so I never had to fear taking him anywhere as I had the paperwork to prove it. The law has since been extended to cover service dogs, and for those not graduated from an accredited facility, they have to pass some sort of test.

    We had a customer in the pharmacy who would bring her sheltie in with a little cape on, and she said it was a service dog. She would get her free makeovers then leave. That dog would bark and growl at every person that walked by. I knew she was a fraud – but rather than call her on it, I asked her a few pointed questions: “Which organization trained your dog?” Red flag response … “I trained it myself!” “Which test did you have to perform to get certified?”. Red flag response …. “Ummmmmm…” She never came back after that. Apparently, you can buy service dog capes on the internet.

    The law here states that while the dog must be allowed access, the owner / manager of the facility has the right to ask the dog be removed if its behaviour is not under control. Most trained dogs are not food-motivated – part of our training was to sit at a table with the puppy laying underneath, and the trainer would toss bits of ham, cheese and kibble down there. The dog was not allowed to make a move towards the food. They’re trained not to bark while “in cape”. So if a “service dog” is barking, snapping, or eating food off the floor, chances are they’re lying, and they have no legal right to bring the dog in.

    Regarding the seizure dogs, we had a local pre-schooler diagnosed with Lennox-Gastaut, and her family raised tens of thousands of dollars to buy a seizure dog from the U.S. They get back here with it to find out it’s not from an accredited facility, so they had to jump through many hoops to get the school to accept it. She was put in touch with me, and she was telling me that to train him to detect the seizures, they would collect saliva from the girl during a seizure, put it in a vial, and use that to train him to bark and paw the ground before. Sadly, she suffered from several a day, so it wasn’t hard to collect a sample. Mostly, the dog was trained to “ground” her so she wouldn’t run off, and to find her if she did. The seizure detection part was quite imperfect, but he was solid in every other way.

    I’m proud to say our puppy graduated from college, and has been faithfully guiding a blind physiotherapist for 2 years now. He LOVES life out of the cape, and is a most devoted servant while in it.

    But my advice to those who are bothered by dogs, check out the local law, and don’t be afraid to challenge people if their dog is disruptive or behaving badly.

  7. LMA says:

    I’m with Katwa — while it certainly sucks if you are deathly allergic to dogs and have a problem encountering assistance dogs, honestly, you’d have the same issue if they were all seeing-eye dogs (in other words, definitely legit) so it’s (unfortunately) on you, just like it is the responsibility of someone deathly allergic to peanuts or whatever. As for the issue of whether these animals can “actually” help, again the “truth” is, if the person with the animal thinks so, it does. Maybe the dog can’t *actually* detect seizures before they happen, but if the person with the seizures feels comforted by the fact that when they awaken, disoriented on the ground, their dog is lying beside them licking their face, then that’s an effective assistance dog. I’ve seen numerous stories and articles by and about people in wheelchairs who talk about how isolated they feel or, alternately, find themselves the subject of unwanted attention, but who once they have a dog on a leash beside them, discover that people are attracted to the dog and thus have “normal” conversations with the owner. If a person is subject to agoraphobia or panic attacks, but feels comfortable going to the supermarket if they have their “assistance cat” with them, then that’s an effective, and IMO, legitimate issue.

    Sh*t like “swimming with the dolphins to ‘treat’ autism,” well, dolphins are not domesticated pets so that should be illegal (as should keeping them in aquariums, but that’s another story). I think this entire “issue” is akin to the old saying “better to free a thousand criminals than to execute a single innocent man.” Yes, there are a few people with allergies who are going to have to take extra care, and yes, there are a few jackasses who are going to pretend their lap dog is for therapy, but that’s just the cost of helping legitimately disabled people.

  8. qetzal says:

    LMA,

    Yes, there are a few people with allergies who are going to have to take extra care, and yes, there are a few jackasses who are going to pretend their lap dog is for therapy, but that’s just the cost of helping legitimately disabled people.

    You realize this argument can be turned completely around? “Yes, a few people with service animals are going to have to do without them in enclosed public places, but that’s just the cost of helping legitimately allergic people.”

    I agree that if someone thinks their animal is helping them, it probably is. But that shouldn’t automatically trump another person’s needs. After all, it’s at least possible for a person with a service animal to leave the animal elsewhere. An allergic person doesn’t have that option.

    I’m not saying legitimate service animals shouldn’t be allowed in doctors’ offices or airplanes or whatever. And I agree we can’t completely eliminate jackasses who will try to take advantage (either by exaggerating their need for a service animal, or by exaggerating their allergic condition!). But I don’t agree that the onus is just on people with severe allergies to take extra care. People with service animals need to make reasonable accomodations for others, too.

  9. BillyJoe says:

    Amnerica is a weird place.
    I have just not encountered this problem here in Australia.
    There are dogs for the blind and that’s about it.

  10. Kultakutri says:

    I agree with BillyJoe to an extent. (Greetings from somewhere in Europe)

    Anyway, I’m depressed since just about forever. We got a husky when I was 16 and hanging around with the dog did have a relaxing effect. (Admittedly, when one is running in a tow of a hyperactive puppy, endorphins abound.) I now have a cat for the same purpose – not for running around with, to keep me silly and sweet company. I suffer from really bad SAD aka winter depression and having the cat around does help things. She’s an attention whore who loves company and compared to people, she has soft paws and smooth fur, doesn’t want to talk weather or politics and playing or otherwise interacting with her makes me feel good for a while. I don’t know what cats do to chemistry of depressed brain or how to design a test to figure out how cats or other animals improve something in objective measures.
    I wouldn’t trust my cat to warn me about cancer. Her excellent sense of smell is limited to locating fish and cookies. Maybe if tumours were made of tuna….

  11. BillyJoe says:

    Actually, Kultakutri, there is a medical condition that smells like fish….but I’m not going there!

  12. Kultakutri says:

    @ BillyJoe: I’m sure that any self-respecting cat would smell the difference. However, I’m not trying to find out.

  13. LovleAnjel says:

    I’d be interested in a double-blind smell test of the cancer dogs. I first heard about them over a decade ago, the fact that there isn’t much evidence yet paints a bad picture.

    As an aside, we visited the in-laws over the weekend, and their german shepherd dag was extraordinarily interested in smelling my navel. Turns out the piercing had become infected. Now, she also extremely interested in everyone’s butts, so what does that tell you?

  14. mousethatroared says:

    I’ve been interested in service dogs for a while, I’ve also been interested in dogs being used to detect cancer. The linked article on the cancer detecting dog research states.

    “Marine, a specially-trained 8-year-old black Labrador retriever, detected colorectal cancer 91 percent of the time when sniffing patients’ breath and 97 percent of the time when sniffing stool, according to a study published Jan. 31 in the British journal Gut.

    She even beat the fecal occult blood test, the most economic and non-invasive screening for colorectal cancer, which positively predicts the presence of cancer only 10 percent of the time, according to lead author Dr. Hideto Sonoda, from Fukuoka Dental College Hospital in Japan, and colleagues. ”

    I guess I’d be interested to hear more details in how and why these results are unimpressive. There was a more in depth discussion of the topic on NPR a while back, that I thought was reasonably interesting.http://www.npr.org/2011/02/04/133498144/can-dogs-smell-cancer

    Regarding service dogs. I thought I’d add that service dogs also work with people who have hearing loss. They can alert their people of sounds that they might not hear when not wearing hearing aid (fire alarms while they sleep, alarm clocks, children crying at night) or they can help people with hearing loss who do not use hearing devices.

  15. Scott says:

    @ mousethatroared:

    The information in that article isn’t enough to base any conclusions at all on, because it only talks about sensitivity (i.e. finding it when it’s there) not specificity (not finding it when it’s not there). So false negatives may be low, but what about false positives? I can easily produce a test which detects 100% of cancer – it just gives a positive result no matter what. Is Marine actually any better than that, or not?

    In short, without measurements of both sensitivity AND specificity, no conclusions whatsoever may be drawn.

    Also, Science Friday has lost all credibility lately – when Andrew Weil is given a completely uncritical platform, and that’s not an isolated incident, they really can’t be taken seriously anymore.

  16. Alia says:

    A friend of mine was saved by her cat. But it’s a sad story, really, and there is nothing extraordinary in it.
    It was a winter evening, she was at home when she noticed her cat started behaving strangely. It looked as though it had some kind of seizure or fit. So she put it into a special carrying bag to take it to the vet. As soon as she went outside, the cat came to and started to behave normally, but when she came back in and put the cat on the floor, it had another fit. And then she realised – it was winter, she had a gas heater, it malfunctioned and carbon monoxide started filling her flat. Combined with carbon dioxide, it is heavier than air, so the cat was the first to feel it. Nothing extraordinary, just biology.
    And the story is rather sad, because the cat did not survive the poisoning after all.

  17. Calli Arcale says:

    I can see a legitimate use for assistance dogs in people with epilepsy; a particularly large and sturdy dog can be trained to act as a physical support for the person. The useful of this likely depends on the nature of the person’s disability, but an assistance dog can be trained in a great many ways. The key, of course, is “trained”. I have little patience for the concept of “companion animals” being allowed in under the mantle of ADA compliance. Assistance animals should only be permitted where they are actually necessary, not just *nice*.

    In addition to seeing eye dogs, there are hearing ear dogs and helping paw dogs. When I was in high school, my class got to meet a quadriplegic (she had some movement in her arms, but not much and required a brace to have any sort of a grip). She had a trained dog who picked things up for her and opened doors for her and things like that.

    I could definitely see dogs being used to detect cancers; they have extraordinarily sensitive noses. I would think the best way to study this would be to first determine whether they have predictive value sniffing various samples, and then start whittling down the substances in the samples to find out what the actual thing is they’re sniffing. Then, as an alternative to using trained dogs, a test might be developed. And if this works, there’s no reason you’d have to limit it to dogs. Rats and wasps are also trained for scenting, and much more cheaply than dogs. But you first have to figure out what to train them to, and that’s the hard part.

  18. mousethatroared says:

    qetzal “I agree that if someone thinks their animal is helping them, it probably is. But that shouldn’t automatically trump another person’s needs. After all, it’s at least possible for a person with a service animal to leave the animal elsewhere. An allergic person doesn’t have that option.”

    If a person is in danger or can not function normally without their service dog, then how possible is it for them to leave the animal at home. (Much less their clothing which probably carries animal hair and dander as well).

    Some people visiting a hospital are severely allergic to latex, do we require people leave all latex containing products at home?

    An expectation that the public can leave all items that may cause an allergic reaction in an individual at home seems unrealistic.

    Perhaps one answer is that hospitals could avoid placing the patient with a therapy dog in a room with a person who is severely allergic to dogs.

  19. mousethatroared says:

    Scott, When you talk about the article, are you talking about the ABC article, the paper in GUT or my NPR link? As I recall the link I posted didn’t have much in the way of conclusions. The discussion seemed to focus on plausibility and possible things to consider for future research. The doctor (Dr. BEAUCHAMP) being interviewed summarizes his research…

    “Although many people believe that dogs can do this – or other species as well – I doubt that it will actually become a useful technique for animals to make the diagnosis. So we really want to know what the compounds are, what are the odors, so that we can develop devices or instruments that could actually make these distinctions.”

    Off Topic —- Sorry you don’t like Science Friday, Scott. I’ve enjoyed many of their segments. I’ve particularly enjoyed their interview with Paul Offit. I also enjoy many of their episodes on medicines or therapies in research that may become a reality someday. Those topics are seldom covered on SBM, but they fascinate me and give me some hope for the future.

    In fact, I listen pretty regularly and I don’t recall hearing anything that sticks out as being contradictory to the information I’ve received reading SBM. Apparently I missed the the Dr Weil episode, though.

  20. Scott says:

    The ABC article and NPR link. I hadn’t looked for the original in particular at that point, though I’ve dug it up since (PMID: 21282130). The abstract claims 99% specificity as well, which is promising. Looking more into the (free) paper, however, it seems pretty preliminary to me. The test was for picking the “right” one of five samples, NOT “does this person have cancer or not.” It’s unclear to me that this would actually translate into a meaningful test, though it’s more promising than the reporting implied.

    And it’s not that I don’t “like” SciFri, it’s more that they’re turning into PopFri, without any critical evaluation whatsoever of whether what they’re presenting has any grounding in reality. Weil was far from an isolated incident. This very dogs question is an excellent example of anti-science; how could any real science reporter possibly miss the sensitivity/specificity issue? The episode on music therapy also stands out in my memory as a recent mind-bogglingly egregious failure.

  21. mousethatroared says:

    Scott, – I heard the piece on music therapy and I did think that at least one of the interviewees were a bit bubble gum, but I also did not hear any claims that music caused miraculous healing or anything beyond lowering stress for OR or ER patients and providing an engaging form of speech therapy for stroke patients. Having sat in on 100′s of hours of speech therapy and drills, I think that anything that makes the process more engaging or pleasant for the individual patient while still getting them to practice target activities is thumbs up in my book.

    What claim was it specifically that you were concerned with?

  22. CMcC says:

    “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).”

    Are you referencing a specific incident here? If so, you might have said something like, “such as in the case of the pit bull owner who defended their dog..” to make that clear.

    If not, why perpetuate stereotypes and misinformation, something this blog is supposed to be against, with the mention of a specific breed? A properly treated and trained “pit bull” (I don’t know if you are referring to the American Pitbull Terrier, or using it as a general derogatory for bully breeds) is no more dangerous to humans than any other breed of comparable size. Nor is any other improperly trained or mistreated breed of similar size any less dangerous.

  23. FelixGutt says:

    As a prior owner of a Pit Bull/Boxer hybrid I have been interested in any statistical evidence that would show whether or not they are actually more dangerous than other large dogs. I was able to find a CDC report on DBRF (Dog Bite Related Fatality) where Pit Bull breeds had two to three time the incidence of Rottweilers and German Sheppards but I was unable to find good census figures to be able to weight (or average) the counts appropriately.

    Just a few months ago Brian Dunning (http://skeptoid.com/episodes/4288), who did a much more thorough research than I have, did a podcast/blog on the subject of dog attacks and had similar difficulties finding good data. He brought up the additional point that I had not considered:

    “Some percentage of potential dog bite scenarios are always going to be set up by aggressive dog owners; so statistically, we’re always going to see a correlation between dog bites and certain breeds that were selected based on reputation, whether that reputation is deserved by the dog or not.”

    I can understand if Pitt Bulls were just being used as an example of a large dog that has been bred for aggression (similar to Akitas, Chow Chows, Rottweilers and German Sheppards) as I had little fear of my wife being attacked when she was home alone with the dog. However, if there is solid evidence for Pitt Bulls being exceptionally aggressive compared to other similar breeds I would love to see the resources.

    Regards,

  24. CMcC says:

    I completely agree with the Brian Dunning quote. The APBT has, unfortunately, become a target for unsavory people. What most people forget about the “Pit Bull” is the fact that it’s a TERRIER. So yeah, they are high strung, have a lot of energy, and need proper training. But the same can be said for many other breeds which are not a target for cruelty and thus, less likely to be involved in unfortunate incidents.

    When bred by legitimate breeders (as in, not backyard breeders and thugs who breed them for fighting), aggression is NOT a quality that is bred for. No legitimate breeder selects any dog to be aggressive towards humans. In fact, due to their strength and potential to injure, the APBT was bred to be quite the opposite, and as a result they are incredibly aware of and sensitive to the emotions of humans. They were used as “nanny” dogs, and enjoyed quite a long history as family dogs.

    I doubt you will find any real evidence that they are exceptionally aggressive under non-abusive circumstances. I’ve never been able to find any myself (not that that made a difference when I tried, unsuccessfully, to obtain renter’s insurance).

  25. DugganSC says:

    More recently, I had someone point me to articles showing that drug-sniffing dogs may be much less accurate than we thought. Namely, they’re finding that there’s a “Clever Hans” problem where the number of false positives increase significantly in cases where the handler believes drugs to be present. Statistics are a bit harder to ferret out namely because stops that don’t result in drugs being found generally don’t indicate whether a dog was used. Makes me wonder if something like this might apply to the “cancer detecting dogs”.

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