Dog Behavior Blog

Do Dogs Understand Contagious Yawning?

When we yawn, it seems like the whole world yawns with us. Let one person start to yawn, and pretty soon everyone else is yawning too. Chimps also yawn contagiously, and possibly some other primates as well.

But what does yawning mean to a dog? Because dogs and humans have been associated for so long, is it reasonable to expect that when we yawn, our dogs will yawn along with us? These are the questions that are asked by two recent articles.

In one of the articles (Joly-Mascheroni et al. 2008. Dogs catch human yawns. Biology Letters 4:446-448) the authors had 29 dogs watching a human yawning, and recorded that 21 of the dogs yawned in response. The authors suggest that this represents a rudimentary form of empathy that dogs might feel for humans, causing the dogs to yawn after they see a human yawning.

In the other article (Harr et al. 2009. Do dogs (Canis familiaris) show contagious yawning? Animal Cognition DOI 10.1007/s10071-009-0233-0), the authors showed 15 dogs video clips of either humans yawning or dogs with either yawns or open mouths, and recorded how many dogs yawned under these circumstances. Only one dog yawned in response to the video clips, and this was to human yawns.

So here we have a difference. One article says that dogs yawn in response to human yawns, and the other article says that they don’t. How do we find our way out of this?

One problem is that there are a lot of unknown factors that could influence the interpretation of these results.

For example, can dogs see and understand video clips? My dog Raja seems utterly indifferent to what is happening on the TV screen, even when there are dogs bouncing around in commercials.

And even if they can see what is on the screen, can they interpret what they are seeing? The other day I came across a website that was talking about the work of Samuel Renshaw, a pioneer in human perception research. The website had a picture that Renshaw showed to people, asking them what the picture represented. I could not figure out what was in the picture until I saw the answer, and then it was obvious to me. If you are curious, take a look at the picture at: http://www.enter.net/~torve/critics/Renshaw/notassmart/notassmart1.html and see if you can identify what is there.

Also, when seeing real human faces yawning, are the dogs responding by yawning through empathy, or are they yawning because of discomfort?  In a book called On Talking Terms With Dogs: Calming Signals, Turid Rugaas describes a yawn as a calming signal that one dog gives to another (or to a human) signifying that the dog is not a threat, as a way of defusing a potentially stressful or aggressive situation.

When I first got Raja as a rescue dog, I would extend my hand to him to try to get him familiarized with my smell. He would often yawn in response. I understood this to mean that he was stressed and nervous, and I made sure that I did not push my attention onto him. Could the dogs watching yawning humans have responded by yawning because they were feeling stressed in the experimental situation?

What it comes down to is that some of the time, we know surprisingly little about why dogs do what they do.

--Con Slobodchikoff

It Doesn’t Mean She’s Been Abused

“She must have been abused.” I hear this so often from people whose dogs cower or otherwise express fear in response to certain objects or certain types of people. It’s natural to think that reactions to seemingly innocuous stimuli must be indications of previous abuse. It’s easy to imagine that a dog who is scared of children has been teased by them in the past. Similarly, it’s perfectly understandable to imagine that the only reason a dog would react so aversely to a broom is because of a previous terrifying experience with one.Many clients have told me that their dog immediately cowered the instant that they picked up a broom, a mop, a stepstool, or even a garbage can.

 

The behavior that most commonly elicits concerns of abuse in a dog’s past is that the dog is only scared of men. While it is always possible that a man has harmed the dog, it is a fact that fearful dogs are often more reactive to men than to woman or to children. To dogs, men are generally more intimidating due to factors such as larger size, broader shoulders, deeper voices, and facial hair. It is very rare to meet a dog who is more afraid of women than of men. Is this because the sickos out there abusing dogs are all men? No! It’s because of fearful dogs’ natural inclination to be more afraid of men.

 

A variation of the assumption that a fear of men results from abuse by a man is that fear of people with hats, or backpacks, or carrying clipboards indicates past abuse by a person sporting those same objects. While this cannot, of course, be ruled out absolutely, it is much more likely that the dog is simply not used to people with these extra objects. Dogs don’t seem to understand about removable parts and many are frightened by anything that changes the overall silhouette of a person. Instead of seeing a person with a hat and backpack for example, dogs may see a strange shape that they can’t identify. In fact, many dogs have shown fear towards a person they know well and love until they remove the hat, at which point the dog stops appearing fearful.

 

Not every dog who exhibits fearful, reactive behaviors was a victim of abuse. Certainly, and most regrettably, there are dreadful people out there who abuse dogs, and there is no question that dogs who are abused are reactive to objects and types of people with whom they have had bad experiences in the past. However, for many dogs, other explanations are much more likely. I do find small comfort in knowing that there are many dogs out there who people suspect of being abused that were not likely victims of it.Dogs often react to sudden movements or anything that is unfamiliar, especially if they are genetically prone to develop neophobic tendencies or they were not exposed to many novel experiences as puppies.

 

I’ve had many lovely clients who have had a dog since the dog was only weeks old with these fearful, reactive behaviors and they say, “People are going to think we’ve abused her, but I swear we’ve never hurt her.” It’s a pleasure when I can reassure them that I do believe them and for very good reason.

 

--Karen London

 

Is It Normal For Dogs To Eat Grass?

My two Standard Poodles, Zephyr and Raja, are as different as night and day when it comes to eating grass. Zephyr would make a beeline towards any grass stems that he saw and start munching on them right away. After a few minutes of chomping on grass, he would have the tell-tale signs of what comes next: his stomach would start to heave, he would start to make gulping noises, and soon all of the grass would come back up, accompanied by a frothy yellow liquid from his stomach. Zephyr was so enthusiastic about eating grass that one time he ate some kind of grass leaves that had sharp edges, damaging his throat. He went around coughing for about three weeks after that, but the experience did not deter him from wanting to eat as much grass as he possibly could. Raja, on the other hand, could take it or leave it. When Zephyr was eating his fill of grass, Raja would take a few mouthfuls to be polite, but otherwise he was not interested. And he never vomited what he ate.

As I was thinking about this difference in behavior, I came across an article that was published last year about plant eating by dogs (Sueda, KLC et al. 2008. Characterisation of plant eating in dogs. Applied Animal Behaviour Science 111: 120-132).

This article reported the results of a couple of surveys of dog owners whose dogs had eaten grass or other plants. One survey was given out to people who brought their dogs to the outpatient clinic at the University of California, Davis, Veterinary Medical Teaching Hospital. To guard against any biases in reporting, the owners were not told that the survey was designed to assess plant eating by dogs. Instead, they were told that the survey was to provide information about the general eating behavior of pet dogs, and there were questions about the diet of the dogs, whether the dogs ate non-food items, and also whether they ate plants. Of the 47 dog owners whose responses were analyzed, 79 percent reported that their dogs ate plants, and 95 percent of those dogs primarily ate grass.

The authors then did an internet survey of plant eating by dogs. They analyzed 1571 responses. Most people (98 percent) reported that their dogs ate grass at least some of the time. Other plant material included berries, sticks and leaves. Most of the owners (92 percent) said that their dogs were not ill before eating plants, and relatively few (22 percent) said that their dogs vomited within one hour of eating the grass. Those dogs who were fed a commercial diet were more likely to vomit after eating grass than dogs fed a home-cooked or raw-food diet.

When the authors considered the results by age and breed of dogs, some interesting trends showed up. Older dogs (9 or more years old) tended to eat grass more often than younger dogs (less than one year old), although younger dogs tended to eat more different kinds of plants overall than older dogs. Also, older dogs tended to vomit more after eating grass than younger dogs. Among the different breeds, hounds and toy breeds tended to vomit more than other breeds.

Ultimately, the authors of the study could not come to any conclusions as to why dogs eat plants, particularly grass. Here I should say that some plants are very toxic to dogs, particularly some houseplants, and dogs definitely should not eat those plants. But as to why dogs eat grass, the authors were left only with some speculations. One idea was that the grass somehow helps remove internal parasites from the stomach, and the authors suggest that this might explain why older dogs, who might be expected to have accumulated more intestinal parasites, eat more grass. Another idea was that the dogs are somehow extracting medicinal qualities from the plants that are beneficial to their nutrition.

To get back to Zephyr and Raja, this still leaves me puzzled. Zephyr always had problems with his stomach being upset, and perhaps this was a way of clearing out a painful accumulation of stomach acids. Raja, on the other hand, has a cast-iron stomach. Maybe this is the reason, or maybe it is something else. At least I know that my dogs have good company – most of the other dogs in the world probably eat grass too.

--Con Slobodchikoff