Thursday, December 17, 2015

Let chickens be chickens

A week or so ago I encountered a letter to the editor in our local newspaper that made me peevish. Its author opined that chickens have better welfare when they are kept in rather than out of cages, because when not caged they are liable to get parasites and cannibalize each other.

I responded. But the letter to the editor format restricted me to 250 words, and I had more to say. Luckily, I have you guys to rant to! So here is my original piece in full.

Dan Miner's letter, published Dec. 5, sets up a straw-man argument about the welfare of chickens kept in versus out of cages. I'm responding from my experiences as a veterinarian with a special interest in animal welfare.

Are chickens in cages free from walking in their own feces? Yes – because they're standing on wire, which is unhealthy for their feet. Are chickens out of cages walking in their own feces? Only if you keep them crowded too close together. If you keep them with enough space that their surroundings don't fill with poop, then no, they won't be walking in poop.

Are chickens in cages able to engage in cannabalism? No – but they're denied healthy social interactions as well. Chickens don't actually want to kill and eat other chickens. They just do it if they're highly stressed. Keep them in a healthy environment where they have some space and the ability to engage in species-appropriate activities, like perching and scratching for bugs, and they'd much rather do those things instead.

Does the cage system protect chickens from parasites? Sure – and keeping a human in a glass bubble keeps them physically free of parasites, too, but would anyone with a normal immune system be willing to live like that just to avoid normal diseases? Healthy, unstressed chickens have robust immune systems that can handle normal diseases. But a stresssed, crowded animal isn't a healthy animal. When bird flu swept through commercial chicken farms this summer, resulting in massive numbers of deaths, which populations stayed healthiest? The outdoor birds, who were unstressed because they had the ability to engage in species-appropriate behaviors, and therefore had robust immune systems. The stressed-out, crowded indoor birds had weak immune systems with no ability to fight off the virus, and were so packed together that when it got into those populations, it swept straight through.

Chickens are only healthier in cages compared to out of cages if the out-of-cage environment is a crowded, stressful one. Many of those environments are, of course. I encourage those who care about chicken welfare to purchase eggs from chickens who are “pastured” or kept “on grass.” Mr. Miner is correct that “cage free” doesn't mean good welfare. He just doesn't realize that there's a better way to raise these animals – with enough space to move around and the opportunity to scratch around and hunt for bugs. Those are happy chickens.

Monday, December 14, 2015

Science with a sense of humor

I’m writing a peer-reviewed article right now. I can almost guarantee it’s something pretty much none of you will be interested in (it is not about dogs or foxes, but about genomics technology), but when it’s out I’ll do my best to blog about it in a way that makes it seem exciting. We’re at the review stage: reviewers give us a bunch of comments, we make the changes to the article, then we write a letter back to the reviewers. The letter is supposed to say things like “Thank you so much for your insightful comments. We made all the changes you suggested!”

One reviewer comment pointed out that at one point in the article, I had referred to humans as a model species. Now, model species are normally species that we use as models for humans. The best examples are laboratory rodents: we study rats in the hopes that what is true for rats is true for humans. The rats are a model species.

The reviewer commented “Are humans really a model species?” At which point my boss basically put her head in her hands and was embarrassed that we hadn’t noticed this stupid gaffe we’d made.

In my first draft of the reply letter to the reviewers, I replied to the question about whether humans are a model species: “They are to this veterinarian!” I, of course, love to read human research in the hope that what is true for humans is true for dogs. (But I made the change in the manuscript.)

I pointed this out to my boss and said, “Did you like my veterinarian joke?”

She: “Yes.”

Me: “Is it OK to have jokes in letters to reviewers?”

She: “No.”


Thursday, December 10, 2015

Dog genome ruminations

The other day I was re-reading the original dog genome paper, as you do. This is the paper published in 2005 to accompany the release of the first full dog genome sequence (of a boxer named Tasha) and accompanying annotation (a mapbook of what genes are located where in the very long sequence of bases that is the genome).

You might think that a genome paper wouldn’t be very interesting, because basically the point of it is to say “here is this genome. We published it. It was a lot of work, and it’s done, and now you can use it.” But most groups try to have something interesting to say in their descriptions of a new genome, and this one actually had a lot of interesting stuff about dog genomics in it.

Don’t just take my word for it. It’s open access, so you can read it for yourself.

Lindblad-Toh, Kerstin, et al. “Genome sequence, comparative analysis and haplotype structure of the domestic dog.” Nature 438.7069 (2005): 803-819.

The dog was one of the earlier mammals to be sequenced, so a lot of this paper consists of comparisons between dog and the other sequences we had at the time, human and mouse. We already knew that humans and mice were more closely related than humans and dogs in one sense: they share a most recent common ancestor. This means that as you follow the branches (and tangles) of the tree of life, first you get a branch that divides the most recent common ancestors of human, mouse, dog, and relatives from species like opossum and chicken; then you get a branch that divides the most recent common ancestors of human and mouse and relatives from dog and relatives; and only then do you get a branch that divides the most recent common ancestors of human and mouse. It looks like this:

Tirindelli, Roberto, et al. "From pheromones to behavior." Physiological reviews 89.3 (2009): 921-956. Fig 5
So we’d expect that human and mouse would share more genomic sequence than dog and human, right? Each of those branches in the tree of life represent a point at which one species becomes two, with resulting divergence in genomic sequence. So if the species divergence between humans and mice happened more recently than the species divergence between humans and dogs, then the genomes of humans and mice should look more similar than the genomes of humans and dogs. But it turns out, as this dog genome introductory paper reports, that dog and human share more genomic sequence, more base pairs, than human and mouse do. So how can that be, if humans and mice are closer together on the branches of the tree?

There are several forces contributing to this result, but the one that made me smile was the different rates at which each species reproduces. In the time since humans, mice, and dogs branched off from their shared common ancestor (before humans and mice branched off from their shared common ancestor), mice have had many more generations than humans and dogs. They reproduce so quickly compared to us and dogs that they have more chances to change their genetics from generation to generation. And as a result, while the number of divisions (places where the tree branches) are greater between human and dog than human and mouse, the number of generations of mice between today’s mouse and that last common ancestor of mice and humans and dogs is greater in mice than in dogs or humans. As the paper’s authors put it:

The lineage-specific divergence rates (human < dog < mouse) are probably explained by differences in metabolic rates or generation times, but the relative contributions of these factors remain unclear.

The other way of looking at it is saying that species age at different rates. So while behaviorally modern humans appeared around 50,000 years ago, and dogs appeared arguably 10,000-32,000 years ago, nevertheless the human population is about 4,000 generations old while the dog population is around 9,000 generations old. Because dog generations are shorter.

We created them, but they’re now older than us. Just like how my dog was younger than me when I got him, but aged right past me. Science!

Saturday, December 5, 2015

Teaching genetics

Summer before last, I taught my first online classes, in introductory and behavioral genetics. It was a ton of fun and I learned a lot about how to teach genetics online to students with a variety of backgrounds and interests. I have since been itching to try again after redesigning the courses to take what I learned into account. In addition to my own experiences, I’m drawing on advice from Rosie Redfield’s excellent and very approachable paper on how to design a modern genetics class. She teaches Useful Genetics for EdX based on these principles, so check that out, too!

DNA being repaired by an enzyme

So I’m hugely looking forward to teaching a series of genetics courses for the International Association of Animal Behavior Consultants (IAABC). The plan is to cover all the material that a college-level genetics course would cover, but to do it in a way that makes the material accessible to students who aren’t in college and can’t commit to a massive course all at once. So I’m planning to teach four separate courses. They will be completely modular: you can take them in any order, or take some but not all of them. If they prove popular, I hope to continue to offer them in coming years, so that students can enter and leave the flow of classes without worrying that there won’t be another chance to take a particular class.

Anyways, the first class in this series is starting January 11, 2016, online at IAABC. It’s a course in molecular genetics — what is DNA, what are genes, how in the world do these tiny little molecules deep inside your cells code for processes that make you who you are? (And your dog who he is, and your horse who he is, and...) The topic list for the class is:

  • the molecular structure of DNA
  • DNA replication and mutations
  • transcription of DNA to RNA
  • translation of RNA to proteins
  • protein structure and function
  • genome sequencing
  • variation between individual genomes
  • genetic testing for disease (how it works, how reliable it is)
  • new advances in gene editing
Future classes will cover heritability (how do your parents pass genetic information on to you?), population genetics (focusing on breeds, what it means to be a purebred, and the consequences of inbreeding), and oh yes, everyone’s favorite, behavoral genetics (which you’ll be able to take without taking the others — but you’ll get more out of it if you take the others first).

More info? Sign up? At IAABC.

Questions? Comments? Requests? Bring ’em on.

Saturday, November 7, 2015

Birthday ruminations

I turn 42 today. (This year, I will be the answer to Life, the Universe, and Everything.) Jack, my golden retriever, is 14 or 15 — an old man. When I got him, he was “two or three,” and I was 29. When I turned thirty, I asked him if I was still cool, and I still remember how he replied that I was obviously the coolest person in the world. Back then, I figured he was the mental equivalent of a young adult, like a human in their early twenties, just getting comfortable with being a grown-up, but still having days when you realize you were a kid not all that long ago.

A few years later Jack and I were the same age: I was in my thirties and he felt like he was too. He needed a lot more exercise than I did but both of us had bodies that mostly worked fine (modulo some back problems for me and some minor seizures for him). We got much of our exercise together on long walks.

Jack in his "thirties."

Then one day I realized he was ten and getting older. He didn’t have as much need to run as he used to. I panicked at the thought of losing him, something that had seemed so far off and suddenly had started to loom. So I got a second dog. (A lot more thought went into Jenny’s arrival, but that was part of it.)

Jenny was a year old when I got her, a baby with an adult sized body. She had been poorly (or not at all) socialized and had a lot of learning to do about the world. We bonded closely and I felt so much like her mom in a way I hadn’t felt about Jack for a long time. He and I were more like peers.

Jenny shortly after she came to live with me.

Today Jenny is 6 and I’m realizing she is finally starting to get close to my mental age. She’s physically in her prime and needs lots of time to run. I’m trying to stay fit and noticing that it’s a little harder to do than it was in my twenties. Jack is fighting off creakiness. For a 15 year old golden he’s doing great, still enjoying coming to the park (at a walking, not running, pace). He recently started underwater treadmill sessions at the local veterinary hospital and has experienced a surge of energy as a result. But his body is starting to betray him: his allergies have progressed as his immune system ages, he’s more and more deaf, and he’s not as eager to wrestle with Jenny as in times gone by.

Time passes. I love these dogs so much.

Jack and Jenny in 2015.

Monday, October 26, 2015

What goes on in puppy brains during the socialization period?

Puppy cuteness!
Ever wondered why puppies make and generalize associations so much more easily than adult dogs? Why it is so important to socialize puppies during their first three months -- what is different in their brains after that?

Me too, and I am going to undertake to try to give some answers (as best I can given there's a lot we still don't know about this stuff).

So come listen to me hold forth on socialization, one of my favorite topics, this Wednesday October 28, 8-9 EDT at a Pet Professionals Guild webinar. It is worth 1 CEU for those who keep track of that sort of thing. I promise to do my best to make it a lot of fun.

Learn About the Biology of Socialization with Dr. Jessica Hekman.

If you can't watch live on Wednesday, you can watch the archived version after (but not before, we don't have time travel yet).

Questions about whether it's up your alley? Feel free to ask in comments on this blog!

Tuesday, October 20, 2015

Heroes of the Zombieverse: Ed Yong

I had intended to cover some more researcher heroes of my world before switching over to the brilliant science communicators. But then Ed Yong posted about the most recent dog domestication research, and he did it so brilliantly that I had to write about him now instead of later.

Ed Yong (image from Not Exactly Rocket Science)

Most people aren’t going to read the original studies for all the science they’re interested in. This is partly because it’s hard to keep track on your own of everything that's happening in the world of science and partly because not everyone has access to all the brand-new studies and partly because not everyone can understand them. (I understand some of them in some fields, but there are certainly more out there that I don’t fully get than that I do.)

So we rely on science journalists (and video makers and podcasters and others). We rely on these people to find the interesting stories. We rely on them to tell us why the stories are interesting. And we rely on them to put the right spin on the story: to not blow it out of proportion.

Ed Yong excels at all three of these things. He says that he covers “the wow beat,” meaning stories that are weird and unexpected. But he covers the usual fare as well, and he does so exceptionally well. He finds the humor and keeps you reading, but he doesn’t fall prey to the temptation to suck you in by over-hyping the story he’s covering. He puts the story in the right context, and that’s just really hard to do for someone who isn’t a researcher in the field. Ed isn’t a researcher in any field and yet he manages to cover many fields with insight and panache.

Yesterday Ed published a story in which he covered a recent paper about where dogs were domesticated. Most journalists cover these papers (which come out several times a year) with the breathless report that now, finally, we have found the birthplace of the dog! Ed, however, takes a step back and tells us how this newest paper fits into the long history of other papers which have pinpointed the origin of the dog on several continents and across tens of thousands of years.

I forwarded the story to a fellow graduate student, who reads dog papers every week with me and who does her own research into canid domestication. She commented: “He is my new favorite science writer - totally nailed it.”

Friday, October 16, 2015

Talking about shelter behavior assessments

Today I presented at APDT's 2015 conference on shelter behavior assessments. It's incredibly important to be able to identify dangerous dogs when they come into shelters so we don't put them on the adoption floor, and to be able to identify dogs who we can perhaps help improve their behavior while in the shelter.

Or is it? I talked for three hours -- well, not quite three hours; my amazing audience helped out with some really fascinating discussion -- about how shelter behavior assessments aren't really all that good at identifying dogs who are just sorta likely to be aggressive. They're great at identifying really aggressive dogs and they're great at identifying really safe dogs -- but then again, we don't really need their help at that as it isn't all that hard to do. What neither these tests nor us humans are great at is identifying the in between, hard to categorize dogs.

I argued that we should continue to perform shelter behavioral assessments on dogs because those interactions with dogs give us more information about the dogs' personalities, and that information is useful. What we really should not do is use these tests as yes-no decision making tools for deciding the dogs' fate. They are not decision making tools; they are information gathering tools. One of the other main themes of the talk was that assessing a dog's personality is something that should be done by someone with plenty of dog experience, not the shelter staff member who read the behavioral assessment guidelines once and figures that's all she needs.

After the talk I said hi to Janis Bradley of the National Canine Research Council and she basically said, Hey, fun talk, but I really think we shouldn't be doing behavior assessments on shelter dogs at all. I've asked lots of competent shelter staff if they know which of the dogs in their shelters are dangerous, and they say sure they do. I've asked if it was a behavioral assessment that helped them figure that out and they say it never has been. It's been the dog's interactions with staff and volunteers.

I replied that we really need to collect as much information as possible about shelter dogs, not to identify the easy to identify extreme cases, but to identify the harder to identify in between cases -- the dog who isn't aggressive to all dogs, just certain dogs, for example.

She said sure, but she still thinks a better way of collecting that information is through careful, possibly structured documentation of the interactions of the various shelter staff and volunteers with the dog during its time in the shelter. That's what we should be focusing on.

Now, I am absolutely down with recording as much data as possible about a shelter dog's behavior. But advocating against formal behavioral assessments, even in shelters that have the resources to do them? My heart isn't quite there yet, but it's an interesting idea. If you have opinions, feel free to weigh in in the comments or on Twitter!

Thursday, October 8, 2015

Heroes of the Zombieverse: Robert Sapolsky

If a rat is a good model for your emotional life, you're in big trouble. - Robert M. Sapolsky

When I first decided I wanted to go back to school to learn about dog behavior, I wasn't exactly sure what I wanted to study. I just didn't know enough biology to know how to frame my questions. I clearly remember one day talking to a PhD student about my interests, and she said: "Have you heard of the HPA axis?" I shook my head and she said (a bit darkly), "You will."

The HPA axis is the set of hormonal processes that govern the mammalian stress response, and Robert Sapolsky is its king. He didn't discover it (Hans Selye set that train in motion when he isolated cortisol), but he is the great explainer of what it means for your body and brain to have long term stress. His talk on stress, depression, and neurobiology is a dizzying hour in which he weaves together the effects of hormones and neurotransmitters on different brain regions and leaves you with a deep understanding of the mechanisms underlying depression and how much we have left to learn about how to cure it.

He brings a dry sense of humor to his work, making even his peer-reviewed publications a fun read. I tweeted last week about the latest Sapolsky offering in which he discussed the role of connections between neurons in the amygdala in anxiety disorders: "The road to a crippling anxiety disorder is paved with perky amygdaloid synapses." First use of the word "perky" in a scientific paper? Perhaps at least its first use to describe a synapse.

He's a committed science communicator, publishing books and magazine articles and making his behavioral biology course at Stanford free on YouTube. He seems to be writing somewhat regularly for Nautilus these days. If you want to learn about what stress is and what it does to your body, I recommend his book Why Zebras Don't Get Ulcers, which was my introduction to the biology of stress lo these many years ago.

So yeah, he studies baboons and he writes about humans. And he talks a lot about the ways in which humans are different from other animals.  But these mechanisms of how stress affects the brain and the body, the health consequences of high stress levels, exactly what is different about the brains of really anxious individuals... these questions are absolutely relevant to dogs. For his work on these questions, for his passion for science communication, and for his quirky personality, Sapolsky gets to be the first of the Dog Zombie heroes in this series.


Sunday, October 4, 2015

Heroes of the Zombieverse: the series

The desktop background of our media server (the Linux computer hooked up to our TV set from which we watch videos) is an homage to rock star scientists:
Source: tumblr
(Actually until a few minutes ago it was a much less cool version with only 12 names, but when I went searching for the original to link to it I found this, which I liked a lot better, so I made the swap.)

Sometimes I look at these icons and I think about the contributions each of these individuals made to different branches of science. And then I think, "If I could make my own list of influential scientists, who would be on it?"

Now, time was, this blog was my only outlet for science communication. Every time I got an itch to write about something, it went here. But these days I have lots of places to write, places where I reach a lot more people than this blog. My story about non-surgical cat contraception is on magazine stands right now in a Scientific American special edition; I have two stories at two other magazines working their way through the copy edit/publication process; I'm presenting at the APDT 2015 conference; and I have an upcoming webinar for PPG. So lately when I get an itch to write or talk about something, it ends up elsewhere.

But I miss writing for this blog, and I miss writing in a more free-form style instead of trying to say everything Exactly Right. So I am throwing down the gauntlet to myself: start a series in which I post at least once a week (hopefully more often) about the heroes of the zombieverse. Brownie points to anyone who can predict any of them before I write about them!

And I know we haven't had a very interactive community on this blog, probably in large part because I post so rarely, but if you were so moved as to comment about your personal heroes -- scientists, dog trainers, science communicators, or others -- I'd love to hear about them.

Wish me luck with finding time to write!

Jenny: "Shhh. I'm hunting squirrels."

Tuesday, August 18, 2015

Living with a shy dog: the house full of spiders

I’m lying on my bed, cuddling with the person I love most in the world, periodically eating chocolates. And yet I’m shaking with fear. Just one flight of stairs away from me, the bottom floor of my house is teeming with spiders. Big ones, small ones, masses of them, crawling all over each other, completely covering the floor in a sheet of black. My loved one tells me not to worry. Why would the spiders come up here? I'm being silly. Yet I can’t relax. Who is to say what a spider might do?

No, that didn't actually happen. What did happen was this: I had my shy dog Jenny upstairs in bed with me and I fed her little smelly meaty dog treats while she shivered in terror. Outside, our tenant was moving out, and burly men were carrying boxes and pieces of furniture down the driveway. I knew none of these men were going to come inside, pin Jenny down, and extract her organs, but somehow she couldn’t believe that. Every time I found myself getting frustrated at her over the top reaction to these men from whom she was completely safe, I reminded myself about my vision of the room teeming with spiders. Who am I to say what will happen? Who am I to say what is terrifying?

Jenny, always alert!

Jenny barks in fear when my husband comes home. She loves him, and after her initial startle, she comes up to him to be petted. My husband sometimes gets (only so slightly) frustrated with her: she knows it’s him! She loves him! So why is she scared every time he comes through the door? I imagine what I'd feel if my loved one had a habit of coming home waving a large gun in my face. Even if I knew intellectually that he had no intention of firing it, I’d still feel deep apprehension. I think that the sound of the opening door is as scary to Jenny as the sight of a loaded gun would be to me. When I’m feeling unsympathetic to her fears, it helps me to translate them into images that are as viscerally compelling to me as her fears clearly are to her.

We continue to give her treats and reassurance when something scary happens, to teach her how to relax in the face of her fears, and to provide her with both daily and as-needed medications to aid her brain in processing her fears. Over the years, she is gradually becoming an entirely different dog. But it’s an ongoing process.

Jenny, learning to relax with a loved one.

Monday, August 10, 2015

Dogs and brains link fest

Here's what I've been reading and tweeting about this week (in between scrambling to get an NSF grant proposal submitted):

Tuesday, July 28, 2015

Dogs and brains link fest

I've been doing a lot of writing, actually, but none of it on this blog. Right now I'm working on an NSF grant proposal. This is really exciting for our lab, but it's a lot of writing! I'm also working on a piece for the writing group I was assigned to as part of attending the upcoming ComSciCon-Chicago, a science communication conference, and I just recently submitted another story to a dog-focused magazine (I'll report here when it's published).

As a result, I haven't found the time to write any new blog posts. But there's lots of other stuff for you to read out there, and I report the best of what I find on my Twitter feed. Here are some recent ones:

Tuesday, May 19, 2015

Learn Science free online!

There’s lots of science out there to read about on the internet these days (so go get reading)! For people who came to science after their formal schooling is over, it can be hard to know how to get the basics to understand all this stuff. And I do think it’s important to understand the basics — a solid knowledge of biology is invaluable when you’re trying to figure out if the findings that a starry-eyed science journalist is reporting are as important as they sound, and whether the journalist’s coverage of them is critical enough. (Uncritical science reporting? Oh yeah. There is way too much of it in the world.)

So how do you go about learning Science? Here are some upcoming free online courses that I recommend to you. By the way, if you are a certified trainer or behavior consultant, I recommend you ask your CEU distributor of choice to give you CEUs for taking these classes. They are absolutely relevant.

Animal Behaviour, University of Melbourne (Coursera)

Starts: June 1

This course is about the behavior of wild animals and about the academic study of animal behavior. It’s a different perspective than the applied behavior approach that most trainers are familiar with. According to the course web page, it covers the following topics:
  • Behaviour, Ecology and Natural Selection
  • Genes, Environment and Learning
  • Finding food and avoiding predators
  • Communication
  • Sexual selection and sperm competition
  • Mating systems and sex allocation
  • Parental care and conflict
  • Social behaviour
 Coursera courses are free, but if you want a certificate that proves you took the course, you will have to pay $50.

Essential Human Biology: Cells and Tissues (EdX)

Starts: June 10

Cells: the things that send information around the brain; the things that make and secrete hormones; the things that are responsible for every part of our life. Whenever I teach about neurobiology or hormones to trainers, I wish I could depend on them having a solid cell biology background!

Just as above, EdX courses are free but you must pay $50 if you want a verified certificate.

Introduction to Psychology, St. Margaret’s Episcopal School (EdX)

Starts: June 15; self-paced

I loved taking basic psychology. I’m sure this course will be quite human-focused, but some of the concepts are applicable to other mammals as well. Others are perhaps applicable to working with the human side of the equation. This course reports to cover:
  • An understanding of what psychology is and its history
  • How brain structures function and how neurotransmitters influence behavior
  • Concepts of how we learn as well as components of emotion
  • How a child's mind and personality develops
  • Discover classifications of abnormal behaviors
This course is “self-paced,” meaning that you can take it at your own pace over the course of several months if you so choose. Price as above.

If you think you might take one of these, I would love to hear about it in the comments!

Saturday, May 9, 2015

Can a supplement improve a dog's response to training?

Ah, the sharp focus of a German shepherd.

When I was in veterinary school, my roommate had a dog nicknamed Mr. C who had some focus issues. (She still has him, but is sadly no longer my roommate.) We used to joke that C had attention deficit hyperactivity disorder (ADHD); he just had an extreme case of not being able to keep his mind on one thing for any length of time. Training him was challenging. Hed get excited and then seemed to be unable to absorb new ideas.

I thought of C when a former student of mine, Melissa Hartley, pointed me at this article:

Kano, Masaaki, et al. "Oral tyrosine changed the responses to commands in German Shepherds and Labrador Retrievers but not in Toy Poodles." Journal of Veterinary Behavior: Clinical Applications and Research (2015).


Although ADHD isn’t a formal diagnosis in dogs currently, the authors of this paper hypothesized that a dog’s focus during training may affect their learning just as a human child’s focus can affect their learning. Human children with ADHD seem to have differences in levels of adrenaline and noradrenaline in their bodies, and their learning abilities appear to improve when they are given medication to modify those levels. The authors hypothesized further that giving dogs a supplement which is a building block of adrenaline and noradrenaline could improve their response to training by improving their ability to respond to the task at hand.

Adrenaline (also known as epinephrine) is the hormone that you can feel shooting through your body when you’re startled, during the fight-or-flight response. Noradrenaline (norepinephrine) is a close cousin with similar effects. It seems counter-intuitive that giving a hyperactive child (or dog) a supplement to increase this hormone which is associated with being overly excited should help them focus, and yet this is the pathway that Ritalin (methylphenidate) uses quite successfully to help children with ADHD improve their focus. The brain is a complicated organ, and the effects of moderating particular substances in different areas are unfortunately not always intuitive.

This study looked at the effects of supplementing dogs with tyrosine, an amino acid which is known to increase the levels of adrenaline and noradrenaline in the brain. The question asked in this study was: would supplementing dogs with tyrosine improve their response to training?

The study methods

Three breeds of dogs were tested in the study: German shepherds, Labrador retrievers, and toy poodles. The GSDs and labs were at a training facility for police dogs, while the toy poodles were at a different type of facility. All dogs received three training sessions to learn to sit. Then some of them received a daily tyrosine supplement for three days, and a control group did not. At the end of the three days, both groups were trained again. Urine samples were taken both before and after each training session to test for levels of adrenaline and noradrenaline in the urine.

The training approach appears to have been based on operant conditioning: capturing the sit behavior via a food reward and associating it with a verbal cue.

The results

Dogs were divided into high achievement versus low achievement groups based on the number of times the dog sat after being given the cue. High achievement dogs sat frequently after receiving the cue, suggesting a better response to training in this group.

The urine of all dogs was tested before tyrosine supplementation. Levels in the urine of the toy poodles were significantly lower than the levels in the urine of the GSDs and labs. The poodles also appear to have responded correctly to the sit cue less often than the GSDs and labs in the initial training sessions, though this data isn’t clearly represented.

After three days of tyrosine supplementation, dogs were trained again and compared to control dogs who did not receive supplementation. Did dogs given tyrosine improve in their response to training, compared to dogs who were not?
  • German shepherds: yes
  • Labrador retrievers: yes
  • Toy poodles: no
And they really did improve: the tyrosine-supplemented GSDs and labs responded to the sit command correctly about twice as many times as did the control dogs. The poodles’ performance actually improved a little as well, but the difference was not statistically significant.

Why the breed differences in response?

Why did the GSDs and the labs seem to respond so well to the tyrosine supplementation, and the poodles did not?

Now, with caveats that looking at urinary levels of adrenaline is not the same thing as looking at brain levels of adrenaline (it’s just a lot less invasive to do), it’s very interesting that the toy poodles had lower levels of adrenaline before supplementation than the GSDs and labs did, and that their response to supplementation was different. If we take as a given that toy poodles are harder to train than German shepherds (and I’m pretty comfortable saying that, just from what I know about the two breeds), could part of the reason be a difference in brain levels of adrenaline making it harder for the toy poodles to focus?

Why wouldn’t the toy poodles respond better to the supplementation, then? It’s hard to say. Perhaps the adrenaline pathways in toy poodles function so differently from those of the other two breeds that the supplementation was just insufficient. It’s also possible, of course, that there were confounding factors in this study — for example, the fact that the toy poodles were being raised in a very different environment from the police dogs in training.

Will tyrosine supplementation help my dog focus better?

Who knows? This was an initial study. If you think that your dog is difficult to train because of focus issues, my first suggestion to you would be to make sure you’re making training fun and providing sufficient incentive (treats, opportunities to play).

I would have loved to have seen video of the training techniques used in this study. Were they good techniques, or perhaps could have different techniques been just as effective as tyrosine supplementation?

Was tyrosine supplementation actually effective in these dogs? I’d want to see another study or two looking at more breeds before I was comfortable with the results of this one. Again, it’s hard to trust just a single study; there could be factors at play that don’t come out until the hypothesis has been tested in more situations.

If you really want to pursue this supplementation, be sure to do so with your veterinarian’s approval so you don’t jeopardize your dog’s health.

Thursday, April 23, 2015

Should dog training be 100% positive?

This dog is clearly enjoying being trained.

There's been an interesting discussion recently on a mailing list for animal behavior consultants and hangers-on like myself. (The group is the International Association of Animal Behavior Consultants, IAABC.) These highly-skilled behavior consultants are knowledgeable in how to deal with behavior problems in dogs and other species, rather than focusing on basic obedience or competition skills like agility.

As you may already know, the modern dog training world can be described as split into two factions: those who advocate methods using dominance theory and/or force, such as alpha rolls or leash popping, and those who advocate methods using learning theory and specifically operant conditioning, such as clicker training.The behavior consultants on this list all fall solidly into the latter category, and all agree that the basis of training should not be founded on punishment-based techniques. They are hashing out the question: Is it ever appropriate to use aversives in training a dog?

Because the two factions split mainly on the use of punishment, it can be easy to fall into black-and-white thinking and assume that any aversive is unacceptable, and equate all aversives with pain and fear. But does “aversive” necessarily mean “painful”?

An aversive is something unpleasant. Give an animal something pleasant (a treat) and it will be more likely to repeat whatever behavior it most recently offered (sitting down). Give an animal something unpleasant (a tug on a prong collar) and it will be less likely to repeat whatever behavior it most recently offered (lunging at a passing dog). Both techniques work in getting the desired behavior. Techniques using an aversive stimulus may have side effects, however — in this example, a dog who lunges at passing dogs out of fear may learn to associate pain from the prong collar with other dogs. While he may stop lunging, he is likely to develop other unwanted behaviors, like biting when the other dog approaches close enough.

Pain and fear are absolutely aversives, and I think everyone in this discussion is agreed that pain and fear should be avoided — that some aversives are just too aversive to use. Many trainers in the discussion declare that they would never use a shock collar; some say they might, but only under extreme circumstances, after many other approaches have been tried and failed. Where do you draw the line at “too aversive,” though? That’s a very interesting question, and different trainers have different answers. But can you be a trainer who works in the positive training camp, and still sometimes uses aversives? For sure.

And here’s the thing: it’s the dog who determines what’s aversive. So some tools that we think of as very mild, like a head halter, can end up being quite aversive for some dogs. A head halter — that’s nothing like a prong collar or a shock collar or a choke chain, and it doesn’t hurt the dog at all. But it is (according to many dogs, including one of mine) incredibly annoying to have on your nose. Is it aversive? Yes. Is it inhumane? That’s an awfully strong word for such an innocuous device. But if you use a head halter on your dog, you are not engaging in 100% positive training. You are using a (mild) aversive. Not one that probably involves pain or fear, but an aversive all the same.

And it turns out it’s pretty difficult to train successfully using no aversives at all! Even telling a dog “that wasn’t the right choice” by using a marker like “oops!” during your training can be a mild aversive. Is it okay to train with mild aversives? Everyone has to answer that question for themself, but from my perspective, of course it is. Life has its ups and downs and everyone is going to encounter mild obstacles from time to time, even a pampered dog. The question is how big an aversive you want to throw at your dog, where exactly you draw the line between acceptable and not. That line will be drawn differently for every owner and every trainer.

So when you’re choosing a new trainer for your dog, remember that some will advertise that they use 100% positive methods, but they may not have quite thought through the implications of all of their methods. Others may state that they’re not 100% positive, but that they still use mostly positive methods — and that’s okay. As your dog’s owner and advocate, it’s up to you to talk to your potential new trainer about their methods, discover what kinds of aversives they do use, and decide what’s acceptable for your dog. Just work through the language your trainer uses to make sure that the kinds of aversives they use are at a level that’s acceptable to you, and of course make sure that they use scientifically-based learning theory (look for words like “positive reinforcement” and avoid words like “alpha” and “dominant”). As a dog loving community, we can agree that the use of aversives should be minimized, while still accepting that from time to time it’s okay to use mild ones.

Monday, April 13, 2015

A week of tame foxes

“You're checked all the way through to... some place I can't pronounce,” said the woman who was checking me in at my small local airport in Illinois.

Novosibirsk. It is the third largest city in Russia, located in south-western Siberia. It is the location of the Novosibirsk State University, one of the best universities in Russia, where the Institute of Cytology and Genetics maintains Belyaev’s tame foxes.

(You may already know about the fox domestication project, but if you don’t, Wikipedia has a good primer, and Jason Goldman has written about them.)

The Institute is actually in Academic City (Akademgorodok), a suburb of Novosibirsk. Academic City is an odd blend of the European — my hotel would not have been out of place in France — and the Russian, with its thick stands of birch and fir. During my early April visit, there was still three or four feet of packed snow on the ground, and mud season was commencing as the temperature rose.

The Institute is in a green-roofed building shoulder-by-shoulder with other university institutes. The farm, where the foxes live, is a ten or fifteen minute drive out of the city. I went to the farm daily to study the socialization period in tame and aggressive fox kits.

Tame fox kit (silver color)

I was working with these kits at three weeks of age, before they were old enough to start venturing out of the nest and interacting with the world. At this point they shouldn’t yet have entered their socialization period. Yet you could already tell the difference between the tame kits and the aggressive kits. Kits within a group weren’t identical in behavior: some complained about being restrained, some yelled, some fell asleep, some were calm and silent. However, the aggressive foxes tended to make more noise, and the tame foxes tended to be more curious about their surroundings. Two aggressive fox kits tried to bite. One tame kit did.

As for the adults, I found more behavioral variation than I’d expected there as well, although the head of the laboratory where I work had warned me again and again that the foxes vary sigificantly in behavior. Tame foxes were curious and wanted to interact with us, but some were shy, diving into their nest boxes or to the far side of their cage and then returning slowly. One fox stretched his body out, low to the ground, so that he could sniff my companion’s face without having to commit himself to coming too close. (When I offered to let him sniff my face, he stole my hat and then carried it around his cage while the neighboring foxes watched in fascination.)

Slightly shy tame fox (Georgian white color)

Other tame foxes could not contain their enthusiasm at having people to interact with. They rolled on their backs and made excited yipping noises and wagged their tails. In their joy, they would hold our hands gently in their mouths, something I saw again and again with them but that I have very rarely seen a dog do.

Fox holding my hand in his mouth (platinum color)

I visited foxes from the control line, who had not been bred for behavior. They were simply afraid of us: when their cage door was opened, they retreated. If cornered, they would bite, but any aggression they showed was entirely defensive.

I also saw foxes from the line that has been selected for aggression to humans. Some of them were afraid and aggressed only defensively. Some were more scary, coming forward to the front of the cage to bite again and again. Certainly they were afraid of humans, but something in their brains or hormones makes them more proactive and less passive in their defensive aggression.

Finally, I met rats and mink selected for tameness or aggression. The tame rat that I met was happy to be held and happy to interact with me, but I don’t have enough experience with pet rats to say if this was unusual. The aggressive rat that I met was terrifying, hurling herself at a gloved hand when her cage door was opened and screaming repeatedly, even after we backed off.

The tame mink were less curious than the tame foxes and didn’t seek interaction with humans in the same way. One let himself be held by his keeper but I wasn't allowed to touch him, in case he might try to bite.

Tame mink

Notice the little white patch on his chin — more white coloration is associated with more tameness in both minks and foxes. Another, all-white mink was tamer and I could pet him. He seemed deeply passive, not seeking interaction, just tolerating it.

Tame white mink

Remember that part of the tame fox story — that as the foxes were selected for tame behavior, they started showing characteristics typical of domesticated species, including white patches and curled tails? Only a small percentage of the tame animals have these features, but I saw several piebald fox kits:

Piebald fox kit (silver color)

...and my host kindly pointed out one fox with a gorgeous example of a curled tail.

Fox with curled tail

What an amazing week. I kept thinking: how strangely my life has turned out!

Wednesday, March 25, 2015

Who funds dog research?

As I move through my training and think ahead to my future career, I wonder: who will pay for all this research I want to do on dogs? I have so many questions to ask!
  • What changes happen in the canine brain as it enters, and then leaves, the socialization period?
  • How is the brain of a fearful dog different from that of a confident dog?
  • What are the genetic differences behind these variations?
  • How do environmental differences (prenatal stress, early learning, adult life) change the brain?
In other words, what are the mechanisms in the brain that differ in fearful dogs — receptors, neurotransmitters, synaptic wiring? And how can I learn about them without using invasive (painful and/or terminal) techniques?

Who are the caretakers of Dog, the species, who care about fearfulness? We as dog owners and lovers care, but dog owners and lovers aren’t the ones who are trained to heal unhealthy dogs, to perform research aimed at understanding them, and we (mostly) aren’t the ones who breed them. So who are the groups who are the caretakers of Dog, and what subsets of Dog do they care for?

Image: Who is my caretaker?


We (I am a veterinarian) are trained to heal sick dogs. Relatively few veterinarians perform research compared to those who engage solely in clinical practice. But some do perform research: most commonly as faculty at veterinary schools alongside a clinical practice, or less commonly as researchers without a clinical practice at research instititutions.

Veterinary research, as a result of this strong emphasis on healing the unhealthy, is focused on clinical results. Veterinarians most commonly perform research which asks questions about the effectiveness of particular techniques — medications, surgical approaches, new equipment. Veterinary research very rarely addresses root questions about mechanisms, particularly in the area of behavior. Rather than asking “How are the brains of fearful dogs different?”, veterinary research is more likely to ask how we could fix a fearful dog: “Does this medication make a fearful dog less fearful?”

In fact, as I pursue my mechanism-based questions, I am asked if I miss being a veterinarian. The perception is that because I am engaged in basic, rather than clinical, research, I am no longer working as a veterinarian.

Basic science researchers

If veterinarians do clinical research studies, then who does basic research biomedical studies, studies that look not at how to fix problems but at how the body works? Ph.D. researchers are more likely to do this sort of research, which is why I am currently engaged in obtaining a Ph.D.

Traditionally, Ph.D. researchers have not been interested in dogs. In fact, way back in 2004 when I was originally deciding between a Ph.D. and a D.V.M., I was told by a Ph.D. animal behaviorist, “Ph.D.s don’t study domesticated animals. Veterinarians study those.” (Actually, veterinarians mostly just try to fix unhealthy domesticated animals, not study the healthy ones.)

That perception has changed in a big way in the intervening eleven years. There are now multiple laboratories studying dogs. But where does their funding come from — who cares enough about dogs as dogs, not as models for human problems, to provide the impressive funding needed for a genomics study? (The work I am doing for my Ph.D., sequencing messenger RNA, costs around $45,000.)

The U.S. federal government

The traditional source of funding for basic research is the federal government: the National Institutes of Health for health-based research and the National Science Foundation for more basic research. But these two massive institutions are very much focused on human health — as they should be, as they are funded by the tax dollars of American citizens. The economy can’t support all the research American researchers would like to do, and getting an NIH or NSF grant is becoming more and more difficult as grant funding is cut. Funding to study dogs as models of human disease? Maybe, but isn’t it easier to study laboratory rodents (on which you can perform invasive studies) or work on humans directly? Funding to study dogs as dogs? Go lie down until it passes.

In my experience, the small number of laboratories directly studying dogs are either studying them as models for questions about human health or evolution, operate on a shoestring budget, or have great trouble obtaining funding for what they want to do.

Animal welfare organizations

So who cares about dogs? Animal welfare organizations, some of which are national in scope and do perform research. Some major players in this field are the American Society for the Prevention of Cruelty to Animals (ASPCA), the Center for Shelter Dogs (CSD), and the Humane Society of the United States (HSUS). I am most familiar with the research coming out of the ASPCA and the CSD, and it is exciting stuff. But it is again mostly focused on applied questions: how can we help the shelter dogs in our care?

I reviewed some of the research these two organizations have performed on how to identify and treat food aggression in shelter dogs in my story for the Bark on shelter behavioral assessments. This was ground-breaking research and I am really glad to see it published. But it doesn’t ask the basic (i.e., non-applied) research questions I am interested in: what is it about the brains of these dogs that differs from the brains of dogs without food aggression? That kind of research doesn’t have immediate applied benefit. You can’t take it to a shelter worker with a recommendation about whether or not to put a food aggressive dog on the adoption floor. It is incredibly impressive that these shelter-focused organizations perform any research at all, and it is absolutely appropriate that the research they perform should have a highly applied focus, with clear questions that, when answered, will provide guidance on how to improve the lives of shelter dogs, immediately. They do not have the resources to pursue these sort of mechanism questions that I want to ask, which do not have immediate applicability.

So who cares about understanding how dog brains work, with the hope that that information will provide a base for future applied research? Who cares about the whole species, not just the subset in shelters or the subset in hospitals?

Breed organizations

Breed organizations care very much about the health and welfare of dogs, and in fact have provided funding into the mechanisms behind health issues specific to their breed. A recent paper about associations between spay/neuter status and health issues in Golden Retrievers was partially funded by the American Kennel Club’s Canine Health Foundation (AKC/CHF), and a similar study on Vizslas was funded by the Vizsla Club of America Welfare Foundation. (I blogged about these studies elsewhere.)

These organizations can fund basic research on how and why particular diseases occur in their breeds, and may even be willing to fund expensive genetic studies, such as a recent one on the genetics of cancer in Golden Retrievers, supported in part by both the AKC/CHF and the Golden Retriever Foundation. However, their focus is very much on the problems of a particular breed. My questions are broader: why do dogs of all breeds have different personalities, some more or less fearful? These organizations are really the caretakers of breed subsets of Dog, not of Dog itself.

Who, then?

Who does that leave as a group willing to fund studies on Dog? On problems common to all breeds? On problems which may or may not provide good models for humans? If I hope to one day run a laboratory which studies these problems, who can I hope to help pay for the research?

I would be remiss if I did not mention Morris Animal Foundation here. While their important Golden Retriever Lifetime Study happens to focus on the health issues of a single breed, their mission is to fund research into studies of small animals (dogs and cats), livestock, and wild animals, with no breed limitations. This group is doing important work, and I applaud them.

But one organization is not enough for a laboratory to depend on for survival, especially in these times with research funding so hard to come by. And so I wonder: are we, the dog lovers of the world, the ones to start supporting research into what it is to be a dog? We, who own dogs of all breeds and mixes, with all sorts of problems, who know what problems most plague us as owners — not just medical problems, but behavioral ones?

And so I leave you with my dreams of crowdfunding, in which a researcher proposes a study and asks the public to support it through donations. Such an approach allows the dog community to take the task of answering basic questions about Dogness into their own hands. This direct connection between a researcher and the community affected by their research is a new benefit of this age of social media. Is this approach right for this particular problem? Time will tell.

Image: Will crowdfunding work?

Monday, March 9, 2015

Contexts and cues: the reactive dog brain

A dog on leash, seeing another dog, explodes into a fury of barking and lunging. Reactive dogs, dogs who respond with arousal or aggression to what should be innocuous stimuli, can be very difficult for their owners to manage safely. I've written previously about hormonal changes in individuals experiencing this kind of arousal. But why do their brains trigger the stress response in such inappropriate situations in the first place?

Learning and memory

Past learning, stored as memories, has a lot to do with current behavior. If a dog has made bad associations with something in the past, he has a good chance of expecting a similarly unpleasant experience the next time he encounters it or something that reminds him of it. How he chooses to deal with this situation — aggression or withdrawal — is one interesting question, but right now I’m writing about how he makes associations in the first place and how he retrieves them later.

Learning and memory can mean a lot of different things depending on their context. I’ll be using them in a very narrow sense.

Learning: making an association between a stimulus and a consequence
Memory: the ability to retrieve a previously-formed association
So if a puppy is attacked by another dog, he may learn to associate other dogs with pain and fear. When he later encounters another dog, he uses his memory to retrieve that association. Two parts of the brain which are deeply associated with this type of learning and memory are the amygdala and the hippocampus.

The amygdala is associated with threat evaluation: is that twisty shape I see out of the corner of my eye a stick, or a poisonous snake? Is the dog I am greeting friendly, or about to attack me? People with damage to their amygdalas may have difficulty evaluating threats, to the extent that they may not be able to feel fear. As a result, the amygdala functions in emotional learning: people told scary stories remember them better than less exciting stories partly because of the emotional contributions of their amygdala, which tells them that an experience has some level of threat and should be recorded in memory with particular care.

The hippocampus, on the other hand, is famous for its contributions to learning different locations. London cab drivers must spend years memorizing the twisty street map of their city, and when they are done, their hippocampuses are actually larger in size compared to people who haven’t gone through the training.

When they work well, these two brain structures are an important part of the process of identifying appropriate threats and discarding stimuli that aren’t threatening, based on previous experience. So what exactly is going on when they operate as they should?

Fear conditioning: contexts and cues

The most effective studies that have been done to determine exactly how the hippocampus and amygdala function in learning and memory have used fear conditioning, often in laboratory rodents. Dog trainers use classical conditioning to associate stimuli that a dog considers threatening with something positive, to change the dog’s emotional response to that stimulus — for example, to teach a dog who fears other dogs that they will reliably get food when other dogs approach, so that the dog comes to look forward to the approach of another dog as a chance to get a treat. Fear conditioning researchers do the opposite, teaching a laboratory rat that something previously benign (like the sound of a bell) predicts something aversive (like an electric shock).

It’s unfortunate that so much research has been done on how to teach fear, something we don’t actually want to do in real life. However, what we learned from these studies should translate to the types of classical conditioning we do with dogs, and be even more relevant to helping us understand how fear-based behavior issues come about in the first place.

These studies have shown that that contexts and cues are important in classical conditioning. If you put a rat into a blue cage and then repeatedly play a bell right before shocking him, he will learn to fear the sound of the bell. The blue cage is the context; the bell is the cue. If you move the rat into a purple cage and play the tone without a subsequent shock, the rat will learn that the purple cage represents a different context, and that he does not need to fear the cue in that context. So the cue and the context contribute differently to classical conditioning.

Source:  Nature Reviews Neuroscience 14, 417–428 (2013)

In the case of a reactive dog, we might imagine that this dog spent time in a rough playgroup as a puppy, and learned to associate other dogs with being bullied. Here, the cue is another dog, and the context is the room the playgroup was in.

The hippocampus: learning in context

One of the jobs of the hippocampus is to encode contexts. Those London cab drivers with oversized hippocampuses have countless contexts encoded to represent many different locations around London. The hippocampus of the puppy who had a tough time at playgroup encoded the room where playgroup happened as a context.

In the case of our laboratory rats, the hippocampus encodes the blue cage as one context and the purple cage as another. With a healthy hippocampus, the rat can differentiate between the two contexts, and is fearful of the cue only in the appropriate context. But with a damaged hippocampus, the rat can’t differentiate between the blue and the purple cage. Although he was trained that the bell only predicts a shock in the blue cage, he fears both cages, because his hippocampus is unable to properly represent the context of the blue cage.

The associative amygdala

One of the jobs of the amygdala, on the other hand, is to encode associations. It encodes the association between cue and stimulus (bell predicts shock) and between context and stimulus (the shock only happens in the context of the blue cage). When humans were tested with functional MRI to see which regions of their brain became more active during a fear conditioning trial, the amygdala and hippocampus responded in different situations. When humans were trained to associate a cue with a shock, their amygdala activated in response to the cue. When they were trained to associate only a context with a shock, both their amygdala and their hippocampus activated when they were exposed to that context. The amygdala activated in both cases because the association was being recalled in both cases, but the hippocampus was only activated when the particular context was recalled. Fascinatingly, this study also found that humans with larger hippocampus volume had greater fear responses in fear conditioning trials. There was no association between amygdala size and fear response.

Prefrontal cortex as mediator

We are not, thankfully, completely at the mercy of the whims of our hippocampus and amygdala, subject to uncontrollable fears based on past bad experiences. We have some ability to take a step back and calm ourselves down. One of the parts of the brain involved in this higher-order cognition is the prefrontal cortex (PFC). This region of the brain has direct connections to both the hippocampus and the amygdala and appears able to mediate some of the signals coming from those two regions. Functional MRI studies tell us that while fear acquisition involves the amygdala, fear extinction (learning to let go of a fear) involves the PFC as well. We also know that people who have thicker PFCs are better at extinguishing fear associations. This mediation by the PFC is what lets us take a deep breath and choose not to give in to our fears.

Do dogs have this ability to take a step back and try consciously to decrease their fears? Certainly they are not as good at this skill as humans are, but I wonder if they do have some ability to do this. In a recent post at Reactive Champion, a reactive dog owner describes a situation in which she believes her reactive dog did just that.

PTSD: failure to contextualize?

When this system goes wrong, how does it go wrong? One hypothesis suggests that post-traumatic stress disorder (PTSD) is a disease of failure to contextualize. Humans with PTSD report having flashbacks to previous trauma unexpectedly and uncontrollably, and in inappropriate contexts. If you were in a drugstore during a robbery, it would be appropriate for you to remember that traumatic event when you returned to that location, and even to feel trepidation about entering that store again. You’d probably think about the event a lot for the first days, weeks, perhaps months afterwards, in many other contexts, as well. But your brain should recover, and you should eventually come to not think of it constantly, and only be reminded of it in similar contexts, such as the same or similar locations.

People with PTSD, however, may have trouble limiting their recall of traumatic events to similar contexts, so that they may be retrieving these memories (often vividly) in any and all contexts, years after the trauma has passed. The problem may lie with their hippocampus, which may have difficulty limiting recall by context. And indeed, studies have shown that people with PTSD often have smaller sized hippocampuses compared to the healthy population.

The perspective of the reactive dog

On to the realm of pure speculation, then, because studies haven’t been done in hippocampus function in reactive dogs. But I think the story of the person involved in a trauma who can’t appropriately contextualize her memories is similar to the story of the dog who was involved in a trauma (dog attack, overwhelming experience in a crowded area as a puppy) and can’t contextualize the experience. A dog who is attacked by other dogs at a dog park may learn to fear the dog park, but if never attacked outside of the dog park, should he learn to fear all dogs, everywhere? I’d argue that that’s an inappropriate association for his brain to make, and that the mechanism of failure might have to do with a failure of the hippocampus to appropriately contextualize, just as in someone with PTSD.

I’m certainly not saying that all reactive dogs have PTSD, but I am speculating that the mechanisms might be similar. Does hippocampal function vary across a spectrum, with some individuals having high-functioning hippocampuses and others not so effective ones? Do dogs with hippocampuses on one end of that spectrum have difficulty limiting their negative associations, such that they are more likely to suffer from fearfulness and possibly fear aggression? I don’t know, and I don’t know if the research will ever be done, but it’s an intriguing story to consider.


  • Maren, Stephen, K. Luan Phan, and Israel Liberzon. "The contextual brain: implications for fear conditioning, extinction and psychopathology." Nature Reviews Neuroscience 14.6 (2013): 417-428. [PDF]
  • Feder, Adriana, Eric J. Nestler, and Dennis S. Charney. "Psychobiology and molecular genetics of resilience." Nature Reviews Neuroscience 10.6 (2009): 446-457. [HTML]