Monday, 24 December 2012

Season's Greetings

Christmas scene with a cat drinking milk and dog eating cookies
Merry Christmas!
Photo: Michael Pettigrew / Shutterstock

Seasons Greetings to you and all your furry and feathered friends.

These were our top stories of the year:
Social Referencing in Dogs
Now Where's My Treat?
How to Help a Fat Cat Lose Weight
Behavioural Problems in Rabbits, Rodents and Ferrets
Homeless Pets: A UK Survey


Wednesday, 19 December 2012

Is Timing an Important Feature of the Sounds Dogs Make?

We recently looked at the amazing story of how two dogs had been taught to go into an fMRI scanner – the beginnings of canine neuroscience. Today’s blog is about a study that takes a different, less hi-tech, approach to understanding the canine brain. Siniscalchi et al were interested in how dogs process other dogs’ vocalizations, and whether they show lateralization of the hemispheres – in other words, whether the left half and right half of the dog’s brain have different functions.

To begin with they needed to record some canine vocalizations. They took four dogs (two mixed-breed, one Border Collie, and one Rhodesian Ridgeback) and recorded the sounds they made during a disturbance, isolation, and play. To get the disturbance recording, they had the dog in a car with its owner, and a stranger approach. For the isolation recording, they got the sound the dog made when left on its own. And finally, the play sound came from a play session with a human. 

They then made a set of stimuli, one which involved the normal sound followed by silence, and the other which involved the sound played in reverse followed by silence. If temporal features – aspects to do with timing – are important, the dogs would respond differently to the signals played forwards and backwards.

Headshot of a rottweiler showing its brown eyes, ears and mouth
Photo: Ammit Jack / Shutterstock

Eighteen pet dogs of various breeds took part. They were tested in a room at the University, with their owner present. A feeding bowl was set up with speakers on either side, and the dog’s favourite dry food was placed in the bowl. While the dog was feeding, the different sounds were played through the speakers. The dog’s reaction was observed as a head-turn to the right or left, or no direction. Each dog was tested several times, each period lasting up to 30 minutes, and returned to the lab for additional sessions, until each sound (forwards and backwards) had been tested seven times.

The results showed that when played the normal vocalizations, dogs responded by turning their head to the right (right ear leading). This is thought to mean that the left hemisphere is activated. When the play signal was reversed, dogs turned their heads to the left (left ear leading), which is thought to mean that the right hemisphere is activated. When the isolation and disturbance sounds were played backwards, there was no significant effect, although there was a tendency to turn the head to the left. 

These differences suggest that temporal features of the sounds dogs make are important, as has been found with primate signals (and of course with human speech). The authors suggest that when the play signal is reversed it is completely novel, and that the right hemisphere is responsible for processing novel things. The play signal is a cooperative one, whereas the noises made during isolation and disturbance are made even if the dog is alone. They speculate that this is why they did not get a turn to the right for disturbance and isolation sounds; because the play signal is the most co-operative, it is probably more fixed in its pattern.

This study shows that temporal features of canine vocalizations are important, and also that the left hemisphere is involved in understanding other dogs’ communications. This adds support to the idea that the canine brain has specialization of the hemispheres.

Do you find it easy to understand the vocalizations that your dog makes?

Reference
Siniscalchi M, Lusito R, Sasso R, & Quaranta A (2012). Are temporal features crucial acoustic cues in dog vocal recognition? Animal cognition, 15 (5), 815-21 PMID: 22544303

Wednesday, 12 December 2012

How to Help a Fat Cat Lose Weight

There are several steps you can take if your feline is overweight or obese.

Portrait of a beautiful but obese calico cat


Many cats are overweight or obese. A recent review by Kathryn Michel and Margie Scherk summarizes the problem and the steps that should be taken to help cats lose weight. Their paper begins by discussing the serious health concerns caused by overweight and obesity: an obese cat is almost four times as likely to get diabetes as a normal-weight cat, and more likely to suffer from other problems such as urinary tract disease and lameness.

They point out that just ten extra pieces of kibble a day, over and above what the cat needs, will cause a 12% increase in weight over the course of a year.

Many owners are not very good at recognizing that their cats are overweight. A typical cat should weigh about 4.5kg. Michel and Scherk adapt figures from the Association for Pet Obesity Prevention that scale up cat weight gain to human dimensions.

For example, a cat that weighs 6.8kg – about 50% more than it should – is equivalent to a weight of 98.9kg (218lbs) for a 5’4” woman, or 115.2kg (254lbs) for a 5’9”man.

An obese cat looking at the camera
Apart from using accurate scales, you should also look at the shape of your cat. The waistline should be visible, as should a tummy-tuck, and you should be able to feel the cat’s ribs. 

So what should you do if your cat is overweight and obese? Portion control is obviously part of the solution.

A cat that is a little overweight should have a fixed amount of regular food, while very overweight and obese cats should be fed a special weight-loss diet to ensure they still get enough nutrients.

Many people use approximate measures for food, and an accurate cup measure, or weighing the food, would be better.

Keeping a food diary of everything the cat eats will help you stick to your plan. Remember to include products designed for dental health, as they also have calories.

Michel and Scherk say you can continue to give your cat treats, since it makes the cat happy, but should reduce the amount of kibble to take account of calories from treats.

To lose weight, a cat needs around 60-70% of the calories that it would need to maintain its weight. A substantial weight loss that does not reach normal weight will still have health benefits, so owners of very obese cats should not feel disheartened – they can still make a difference.  

The paper also points out other steps that have been found to make a difference to weight loss, such as feeding via devices that require the cat to do some work: food puzzle toys for cats.

There are several containers on the market with holes in, designed for just this purpose, or you could make your own using a plastic drink bottle.

Cardboard tubes – such as from toilet roll – can be fastened together, and food placed inside so the cat has to reach its paw in.

Another great suggestion is to put portions of the cat’s daily food on a small plate or in a cupcake case and hide it around the house, so the cat has to hunt for some of their food.

A beautiful Ragdoll cat playing with a toy
Engaging in play with your cat will help him or her maintain a healthy weight
These ideas count as environmental enrichment for the cat, and other enrichment activities will help to increase the cat’s exercise.

For example, playing an interactive game with your cat, such as getting it to chase a toy or laser light (they suggest always ending by putting the light on a toy, so the cat gets to catch something and doesn’t feel frustrated).

Cats can also be encouraged to use a treadmill, or taken for walks wearing a leash and harness.

There is some evidence that owners of overweight cats have a tendency to over-humanize them. This comes from a study of 120 cat owners by Kienzle and Bergler (2006) in Germany. This study looked at cats that were not free-roaming (i.e. indoors-only or with access to an enclosed balcony/garden). Normal weight was defined as a queen under 4kg or a tom under 5kg, and overweight as over 5kg or 6kg respectively.

Owners of overweight cats had a closer relationship with their cat, and were more likely to say the cat consoled and encouraged them. They were also more likely to say their cat was like a child to them. While both sets of owners talked to their cats, owners of overweight cats were more likely to talk to their cat, and to talk about topics relating to friends and family or work.

Owners of overweight cats were more likely to watch their cats eat, suggesting that food played a greater role in their relationship. Owners of normal-weight cats were more likely to play with their cat.

Michel and Scherk conclude that it is important to consider the cat caregiver when discussing a cat weight loss program. They say, “The value of encouraging alternative ‘strokes’ – things that make the person feel good about their interaction with the cat, such as play and a sense of pride in achieving weight loss goals – is not to be underestimated. Positive feedback, both from the veterinary team (the outside environment) as well as self-generated by the client, is vital to the success of a weight loss program.”

Their excellent paper is aimed at vets, but it contains many ideas to help the average pet-owner.   

Do you keep an eye on your cat’s weight? And, do you have any tips for feline weight loss? 

References
Kienzle E, & Bergler R (2006). Human-animal relationship of owners of normal and overweight cats. The Journal of nutrition, 136 (7 Suppl) PMID: 16772465
Michel K, & Scherk M (2012). From problem to success: feline weight loss programs that work. Journal of feline medicine and surgery, 14 (5), 327-36 PMID: 22511475
Photos: Thy Le (top) and Tony Campbell (both Shutterstock.com).

Wednesday, 5 December 2012

Can Dogs Use Human Emotional Expressions to Identify Which Box Contains Food?

Dogs are very aware of human emotional states. An earlier blog post looked at how dogs respond to a crying stranger. This week’s post is about whether or not dogs can use human emotional cues to tell them which of two boxes contains a tasty treat.

A labrador retriever with a rope toy in its mouth, looking at the camera
Labrador Retrievers were one of the breeds to take part in the study
Photo: Carolyn Brule / Shutterstock

The research was conducted by David Buttelmann and Michael Tomasello in Germany. They compared two sets of human emotional expressions: Happy vs Neutral; and Happy vs Disgust. They tested 58 domestic dogs (Siberian Huskies, Labrador Retrievers, Golden Retrievers, Border Collies and German Shepherds). The Siberian Huskies were tested at the open air enclosure where they lived, and the other dogs were all tested in a room, mostly with the owner present.

The experimental set-up involved two cardboard boxes, each containing an item that acted as a clue to the experimenter as to which emotion they should display: sausage for the happy condition, wood shavings for the neutral condition, and garlic for disgust.  

The dogs were given a warm-up in which they were shown a pair of boxes and learned that they would receive any food that was in the box they chose. Then a screen was put up, and the experimenter pretended to be busy while an assistant placed items in the boxes.

When the screen was removed, the experimenter came to the table and called the dog over to watch. The experimenter lifted the lid of each box in turn and acted out the appropriate emotion. There were two boxes in each condition, so they acted either Happy and Neutral, or Happy and Disgust, depending on the condition. For the Happy and Disgust emotions, they also said the German word for nightingale in an appropriate tone of voice. This word had no meaning for the experiment, so only the tone of voice was relevant to the dogs.

The dogs were given a chance to choose a box, and then shown the contents. If it was sausage, they were allowed to eat it. Then the whole procedure was repeated. If the dogs showed a bias to a particular side (e.g. they always chose the box on the left), there was another warm-up session in which they were shown that either box might contain food.

The results showed that in the Happy-Neutral condition, the dogs chose the Happy box 52.1% of the time. In the Happy-Disgust condition, they chose the Happy box 54.9% of the time. In each case, this was significantly better than chance, suggesting that they were using the human expressions as a clue.

Some individual dogs performed exactly at chance levels. This was because they chose a side and stuck to it throughout the experiment, despite the warm-up session designed to show that the box on either side could contain food.

For some reason the Siberian Huskies performed better than the other dogs. Since the huskies were tested outside, they may have been able to use smell to distinguish between the boxes, especially since they were tested on a windy day. So a control condition was done with just Siberian Huskies, outside. This had the same procedure, i.e. one box contained sausage and the other contained either wood shavings or garlic, but the experimenter always had a neutral expression. In this case, where the dogs had no emotional expression to help them, they did not perform significantly better than chance. However, they also did not perform significantly better than in the earlier experiment.

These results suggest that dogs can distinguish human emotions, and use them to help identify which of two boxes contains food. However, the reason why the Siberian Huskies performed better than the other dogs is unexplained, which suggests that further research is needed before we can draw a definite conclusion. 

One thing missing from this research report is a consideration of what a social scientist would call the lived experience of the dog. What I mean is that a dog’s experience of observing human emotions may not show them to be a reliable indicator of whether or not something is tasty. Some dogs have a habit of finding things to eat that cause a look of disgust on their owner’s face, even though the dog likes it very much.

This is a fascinating piece of research despite the fact there are a few things to tease out.  I look forward to seeing the follow-up studies. 

What disgusting things does your dog like to eat? As always, feel free to leave any other comments you have about this research.

Reference
Buttelmann, D., & Tomasello, M. (2012). Can domestic dogs (Canis familiaris) use referential emotional expressions to locate hidden food? Animal Cognition DOI: 10.1007/s10071-012-0560-4

Wednesday, 28 November 2012

How Many People Use Electronic Shock Collars?

Regular readers of this blog will know that we take a special interest in research on dog training. We were excited to read a new paper by Emily Blackwell that investigates how many owners use electronic collars on their dogs, and whether or not they think they work.

Two cute dogs looking up at a man with a treat bag on his belt
Photo: Ksenia Raykova

Electronic collars deliver a small electric shock as an aversive stimulus, with or without a preceding warning signal. It is useful to know how many people use them, since a recent British report on shock collars found they have the potential to cause harm if mis-used, and recommended controls on their use and design.

The study took place in the UK and dog owners were recruited via questionnaires distributed to people out walking their dogs, at agricultural shows, at vet surgeries and pet shops. The questionnaire was adapted from a previous study by Blackwell and colleagues. It asked detailed questions about people’s experience at owning and training dogs, about the training methods they used, and about any problem behaviours that their dogs exhibited. The response rate was 27% and a total of 3897 people took part from across the UK.  People in Wales were excluded from the analysis on e-collars, since they are banned in Wales.

The proportion of people using a remote-activated e-collar was 3.3%; 1.4% used a bark-activated e-collar; and 0.9% used an invisible fence. The main reasons people gave for using an e-collar were recall and chasing, and barking. Since those using it for barking were often also using it for other purposes, there weren’t enough participants using it only for barking to assess whether or not this worked. However, there were enough people using it for training recall and chasing to investigate further. By training recall/chasing, they mean teaching your dog to come when called, and not to chase off after other things (like joggers, bicycles and sheep).

The researchers compared the 83 owners using an e-collar for recall and chasing to a subset of the rest of the sample that included 123 owners who were using other aversives (positive punishment) and 373 who were using rewards (positive reinforcement) for recall and chasing. There were no differences between these groups in terms of attending puppy classes or other obedience classes; 69% had attended some kind of training class.

People who trained using the e-collars reported significantly less success than expected, and those who trained using rewards reported significantly more success in training their dogs for recall and chasing. 

Another interesting finding is that men were more likely to say they used e-collars than women. It’s not clear why this is the case, and I would be interested to see more research on this.

The study relies on owner reports and so it is possible there are confounding factors. For example, people who use e-collars might feel a need to justify their use, either by saying their dogs are more disobedient than they really are, or by exaggerating their success. Nonetheless, this is a valuable study because it investigates the training experiences of ordinary dog owners. Since there is a potential for e-collars to cause harm, there would be ethical problems with conducting an experimental study of the use of e-collars with ordinary owners and their dogs.

This study joins a growing list that finds a correlation between positive reinforcement and success in dog training. The authors conclude that “more owners using reward-based methods for recall/chasing report a successful outcome of training than those using e-collars.”

What training methods do you use for recall?

Reference
Blackwell EJ, Bolster C, Richards G, Loftus BA, & Casey RA (2012). The use of electronic collars for training domestic dogs: estimated prevalence, reasons and risk factors for use, and owner perceived success as compared to other training methods. BMC veterinary research, 8 PMID: 22748195

Wednesday, 21 November 2012

Music for Kenneled Dogs

There are many studies on the effects of music, from what kind of music will make us spend more time and money in shops to the effects that learning to play an instrument has on our brains. Now, scientists at Colorado State University have turned their attention to what kind of music dogs might prefer to listen to in kennels.

A siberian husky puppy is chewing on some headphones
Photo: Nata Sdobnikova / Shutterstock

The study, by Lori Kogan and colleagues, took place at a kennel that housed rescue dachshunds (generally long-term) and also boarded dogs while their owners were away. Being in kennels can be a stressful experience for dogs as they are kept in a small space with limited access to outdoors, and limited human and canine company. Kogan et al wanted to know if music would help to make the kennel environment less stressful.

They compared three different kinds of music: classical music (4 tracks), heavy metal (3 tracks), and some music that was specially designed to be relaxing for dogs (1 track). A period with no music was used as a control. The music was chosen as the most popular in those genres (e.g. Beethoven’s Für Elise, Motorhead’s Ace of Spades). In general, the heavy metal had the highest beats per minute and the psycho-acoustically designed music had the lowest bpm.

In total, 117 dogs took part, of which 34 were rescue dachshunds/dachshund crosses, and the remainder were a range of breeds that were at the kennel for short-term boarding. Although many dogs took part in all conditions, some did not, depending on the length of their stay.

The kennels were set up with speakers so that all of the dogs would be able to hear. The music was played in the mornings on days when the kennel was relatively quiet. Each time, the auditory stimulus (music track or silence) lasted for 45 minutes, followed by a 15 minute period of silence. 

The dogs’ behaviour was rated every five minutes during auditory presentations. The researchers assessed whether or not the dogs were sleeping, if they were shaking or not, and if they were making a noise. Initially they had intended to measure barking vs other vocalizations, but in practice it was sometimes difficult to tell e.g. a bark from a yip, and so they just recorded whether or not they were vocalizing.

There were no differences between the rescue dachshunds and the dogs there for short-term boarding in terms of their responses to the music, so the results were combined for analysis. Dogs spent significantly more time sleeping during the classical music than during the other types of music or no music. There was no difference in sleep time between heavy metal, psycho-acoustic music, or no music. In terms of shaking, the dogs shook significantly more during the heavy metal than the other types of music. The results for vocalization were more complex, and showed less vocalization during some of the classical music, and more vocalization when there was no music at all.

The researchers suggest that dogs might be less stressed in a kennel environment if they were played classical music. They were surprised that the psycho-acoustic music did not seem to affect behaviour, but we cannot draw a general conclusion since they only used one track; it could be that other tracks would have an effect. Similarly, since only a few tracks were used of classical and heavy metal, it’s too early to draw conclusions about the genres as a whole. However, this study does suggest that future research, using a wider range of music, could be very interesting. 

Future studies could also play different tracks in succession, since the mode of presentation used here (one track repeated for 45 minutes) might not be appreciated by shelter staff. Whether or not dogs prefer repetition is another empirical question. But this study certainly suggests that kennels could consider the use of music to help dogs relax. Some boarding kennels and cat hotels already use music and TV to keep their clients happy.

How does your dog respond to music?

Reference
Kogan, L., Schoenfeld-Tacher, R., & Simon, A. (2012). Behavioral effects of auditory stimulation on kenneled dogs Journal of Veterinary Behavior: Clinical Applications and Research, 7 (5), 268-275 DOI: 10.1016/j.jveb.2011.11.002

Wednesday, 14 November 2012

Attitudes to Rescue Dogs in Australia


Last week, we looked at a study which found that attitudes to cats predicted public preferences for Trap, Neuter and Release programmes, but knowledge about cats and experience with feral cats did not. But does knowledge and experience predict attitudes to rescue dogs?

A recent study by Kate Mornement and colleagues in Australia answers this question. In Australia, 36% of households have at least one pet dog, but as in other countries, a lot of dogs are in rescue and in need of homes. Understanding perceptions of rescue dogs is important as it can help in finding strategies to increase adoptions.

A dachsund surrounded by autumn leaves
Photo: Ondrej83 / Shutterstock

The internet survey had 1,622 participants and included sections on demographics, attitudes to getting a dog, and beliefs about animal shelters and how they operate. Details of the survey were distributed via social networking, and both dog-owners and non-dog owners were invited to take part. Since some large dog and rescue organizations shared links to the survey, the sample included a mix of participants with and without rescue experience. 30% of participants either worked or volunteered at an animal shelter. Over 80% of respondents currently owned a dog, and only 3% had never owned a dog.

The results showed that 76% of respondents were likely or very likely to get a new dog in the future. Most of the participants said it was likely or very likely that their next dog would come from an animal shelter (85%), rescue organization (86%) or council pound (65%), and only 40% said it was likely or very likely that it would come from a breeder. Another interesting finding is that people think the most important attribute for a new dog is friendliness (rather than, say, obedience).

On the whole people had positive views of shelter dogs. Most people agreed with the statement that family and friends would approve of them getting a new dog from a shelter. This is good news, especially since subjective norms (beliefs about other people’s beliefs) play a role in determining whether attitudes predict behaviour.

There were some areas where shelters could improve. About a third of participants said that shelter dogs are likely to have a behavioural problem.  When participants were asked about how shelter dogs should be assessed, aggression was seen as the most important factor, including aggression towards people, dogs, other animals, and around food.  It seems that shelters could do more to explain to the public how they assess dogs, and how they deal with dogs that fail the behavioural assessment. Many participants did not realize that dogs are euthanized if the assessment finds them unadoptable. I think having a wider discussion about this would be beneficial, not least because many people seem to be unaware of the scale of the problem of homeless pets. 

Since the sample included many people with rescue experience, comparisons were made between them and the other participants. Rescue experience made a significant difference to people’s beliefs: people with such experience were significantly more likely to say a future dog would come from a rescue, and to have positive attitudes towards shelter dogs. Mornement suggests that encouraging people to volunteer at animal shelters could give them a better understanding of what shelter dogs are like. Of course, it is also possible that people who already have a better understanding of animal rescue are more likely to volunteer. Nonetheless, since shelters are always in need of extra volunteers, it’s a good approach to take. 

It reminds me of the contact hypothesis in social psychology. This says that contact with members of another group reduces prejudice since it increases knowledge, reduces anxiety about the other group, and increases empathy for them (see Pettigrew and Tropp 2008 for a metanalysis). Perhaps the same process applies to contact with rescue dogs. For people, it seems that the emotional aspects (anxiety and empathy) are more important than knowledge for prejudice reduction. I would be interested to see future research explore which aspects of experience with rescue dogs improve people’s attitudes towards them. 

This is a fascinating and valuable article for those working in dog rescue. If you would like to read the full paper, the journal has free trial access until the end of the month; follow the link from the reference list below and sign up for the free trial.

Do you have any experience with rescue dogs? And if so, has it changed your perceptions of them?

References
Mornement, K., Coleman, G., Toukhsati, S., & Bennett, P. (2012). What Do Current and Potential Australian Dog Owners Believe about Shelter Practices and Shelter Dogs? Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 25 (4), 457-473 DOI: 10.2752/175303712X13479798785850
Pettigrew, T., & Tropp, L. (2008). How does intergroup contact reduce prejudice? Meta-analytic tests of three mediators European Journal of Social Psychology, 38 (6), 922-934 DOI: 10.1002/ejsp.504

Wednesday, 7 November 2012

Public Opinions on Feral Cat Management


What should be done about feral cats? A recent survey in Athens, Georgia, investigated people’s preferences for three different methods: catch and euthanize, trap neuter and release (TNR), and the establishment of a feral cat sanctuary. Opponents of catch and euthanize schemes argue that it is inhumane to kill cats, and simply creates a cat-free area into which new feral cats will move. Trap, neuter and release programmes involve catching the cats and neutering or spaying them before releasing them; the cats continue to live in the same place, but are unable to breed. The third option in the survey was to “capture and place feral cats in a sanctuary just for them”.

Athens was an interesting place for the study, since the issue of feral cats had been in the local news for some time. A new law was passed just prior to the survey, which effectively meant that TNR was the only option for dealing with feral cats. Previously, anyone who fed stray cats was deemed to be their owner.


Two ginger kittens curled up together on some straw outside a barn
Photo: Shutterstock

People were selected at random and mailed a card which asked them to take part in a survey on the internet. Questions were about knowledge of cats, experiences with feral and owned cats, beliefs about wildlife in the area, and opinions on different options for managing the feral cat population. There were 298 respondents which was a response rate of about 10%.

About 60% of people had seen a feral cat in the last year, and 28% reported seeing a feral cat almost every day. Half of people said that feral cats were “a nuisance”, and 65% felt that something needed to be done about them.  The idea of cat sanctuaries had the most support, with 56% of people agreeing this was an acceptable management strategy; in contrast, 49% said TNR is acceptable and 46% said euthanasia is acceptable.

This level of support for euthanasia reminds me of the American Humane Association's recent survey which found that cats have an image problem - 35% of non-cat owners said they just don't like cats. The survey in Athens found most people recognize that feral cats have a hard life; only 10% agreed that "feral cats live a healthy, happy life". On a more positive note, about a third of participants had adopted a feral cat at some point.

So how did the public rate different management strategies? When questions compared catch-and-euthanize to TNR, TNR was seen as less effective but the most humane, and also the method on which people would prefer tax dollars to be spent. The survey does not seem to have asked whether the cat sanctuary option was considered effective, humane, or a good use of tax dollars.

The study also looked at whether people’s attitudes to cats, knowledge about cats, and experiences of feral cats would predict their views on management practices. Attitudes were important, but knowledge and experience were not. People with positive attitudes about feral cats were more likely to support TNR. Beliefs that were important in predicting support for TNR were those about cat rights, preventing cat euthanasia, healthy ecosystems, and protecting wildlife. Those who felt protecting wildlife and having healthy ecosystems were important were less likely to support TNR, perhaps because they perceived cats as a threat to wildlife. Those who felt cat rights and preventing cat euthanasia were important were more likely to support TNR.

The researchers say that although cat sanctuaries were the preferred option, there are few examples of these in practice, and they would be more expensive than TNR. Given the recent passage of TNR legislation in Athens, they were surprised TNR was not the most supported option, and say that public support for policies cannot be assumed. 

The survey found widespread support for more education about feral cats. This suggests that public education should be part of any feral cat management strategy. 

Do you have stray/feral cats in your neighbourhood?

Reference
Loyd, K., & Hernandez, S. (2012). Public Perceptions of Domestic Cats and Preferences for Feral Cat Management in the Southeastern United States Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 25 (3), 337-351 DOI: 10.2752/175303712X13403555186299

Wednesday, 31 October 2012

Social Referencing in Dogs

When human infants see something they are unsure of, they look to their caregiver to see what their reaction is. This is called social referencing. It has two components: first of all, a look from the object to the caregiver; and second, a reaction to the object (approach or avoidance) that is influenced by the caregiver’s response. This is well established in infants at twelve months of age. Do dogs do the same thing?

Two recent papers by Merola and colleagues set out to investigate, using a method similar to infant studies. They needed a slightly-scary object; something that will make a dog feel cautious, but not so scary that it will turn and run away. They decided to use an electric fan with streamers attached. 

In the first paper, published in Animal Cognition, the owner brought their dog into the room with the fan. The fan was at the far end of the room, and as soon as the owner closed the door, the fan was turned on by remote control. The owner stopped at a specific mark on the floor and released the dog.  The owner then stood still and looked at the fan with a neutral expression (phase 1). What happened next depended on whether the dog was assigned to a positive or negative condition. There were three further phases in which the owner gave a positive or negative response to the fan using speech and facial expression (phase 2), and movement towards or away from the fan (phases 3 and 4). These reactions were later rated by people who were blind to the aims of the experiment, to confirm that they were indeed positive or negative as intended. The dog’s behaviour was observed throughout.

A pretty biewer yorkie with an autumnal display of fruits and foliage
Photo: Liliyana Kulianionak / Shutterstock

Seventy-five dogs took part. Seventeen were excluded from analysis because of mistakes by the owners, and some were excluded from most of the analyses because they confidently approached the fan right at the start. Of the remaining dogs, 83% looked at their owner at least once after seeing the fan. Once the owners started reacting to the fan, dogs in the negative group were significantly more likely to remain still than those in the positive group. Also, in the last two phases of the study (once the owner had moved), dogs in the negative condition spent significantly more time interacting with the owner. This shows they have responded to their owner’s negative message by avoiding the fan.

This study shows that most of the dogs engaged in social referencing to see what their owner thought of the fan. However, the experiment had an initial phase in which the owner was neutral, which is different from studies with infants. This disrupted normal social referencing behaviour, since the owner was artificially silent in response to the dog’s look, and only began to respond after a pre-set time had elapsed. Also, it would be interesting to know whether dogs do social referencing with a stranger as well as their owner.

The second paper, published in PloS One, involved a new set of ninety dogs. This time, both the owner and a stranger were in the room with the dog. Either the owner or stranger acted as the informant, while the other person sat on a chair and read a book throughout, paying no attention to the dog. The experimental procedure was similar, except this time the informant began responding to the fan as soon as the dog looked back at them (phase 1). Then, the fan was turned off (phase 2), and the informant stayed in the same place, but continued to give the positive or negative message every time the dog looked at them. This design is much closer to that used in the infant cognition literature. 

As before, some results had to be discarded either because of errors made by the owners or because the dogs were very confident about the fan. Results from the remaining dogs showed that 76% of dogs with the owner as informant, and 60% of dogs with the stranger, showed referential looking at the informant.  There were significant differences in behaviour depending on whether the message was positive or negative. Interestingly, there is also evidence that dogs responded more to their owner than to a stranger. When the informant was the owner, dogs in the positive group reached the space near the fan more quickly, and dogs in the negative group took longer to reach the fan, than when the informant was a stranger. When the message was negative, dogs looked to the seated person more if it was the owner rather than a stranger, suggesting that they wanted information from their owner too. 

At the end of both studies, the fan was turned off and the experimenter sat next to it and gave the dogs treats. This was to make sure the dogs would not be frightened by fans in future.

These two studies show that dogs use gaze to look at a person for information when they are faced with something they are unsure about, and their subsequent behaviour is based on the person’s reaction. With some small differences, these results are very similar to those found in studies of infants.

Have you ever noticed your dog looking to you for information about something unfamiliar?

References
Merola, I., Prato-Previde, E., & Marshall-Pescini, S. (2011). Social referencing in dog-owner dyads? Animal Cognition, 15 (2), 175-185 DOI: 10.1007/s10071-011-0443-0
Merola, I., Prato-Previde, E., & Marshall-Pescini, S. (2012). Dogs' Social Referencing towards Owners and Strangers PLoS ONE, 7 (10) DOI: 10.1371/journal.pone.0047653

Wednesday, 24 October 2012

Homeless Pets: A UK Survey


The problem of pet overpopulation and homelessness is well known. Getting accurate figures for the number of homeless pets is a more difficult undertaking, since many organizations are responsible for stray and homeless animals. The results of a survey in the UK were recently published, and provide useful information about the scale of the problem, the wait times for animals to be accepted into rescue, and the likely outcome of their stay.

The survey was conducted by Jenny Stavisky and colleagues at the University of Nottingham. They sent a questionnaire to all the rescue organizations they could identify in the UK. They used a snowballing technique, asking each organization to suggest other groups that they should contact. They identified over 2300 contacts, and got an excellent response rate of close to 40%. In some cases, the head office of an organization provided some information, while other details came from the branches.

A lonely pomeranian lies down on the street
Photo: Sergey Skleznev / Shutterstock

The results show that during 2010, the organizations in the survey cared for 156,826 cats and 89,571 dogs. (Remember the real number of homeless animals in the UK will be much greater, since some organizations did not participate). About half of the animals were handed in by their owners, while others came in as strays or were seized because of animal welfare problems. 

The good news is that 77% of the cats and 75% of the dogs were rehomed. Sadly, though, the second most common outcome was euthanasia: 13% of cats and 10% of dogs were euthanized. In other words, 13,000 cats and 9,000 dogs were put to sleep. Although some may have been euthanized because of serious health or behavioural issues, it is inevitable that healthy, adoptable animals were euthanized too.

Another major problem was waiting lists, with 62% reporting a waiting list for cats and 44% reporting a waiting list for dogs. On average, the waiting list for dogs was equivalent to a third of the capacity of the shelters, and for cats it was even greater at half the shelter capacity. The worst case was an organization that had a waiting list of more than 16 times the number of dogs they could accommodate.

The survey also found that these organizations depend heavily on volunteers. Although over 19,000 people were involved in the animals’ care, over 76% of them were part-time volunteers.  The costs are also high; in total, the organizations spent close to 330,000 pounds in the 2009-2010 financial year.

It is difficult to calculate the total number of un-owned dogs and cats in the UK from this survey. The main animal welfare organizations all took part, and most of the organizations that did not respond were small, but it is hard to generalize from these figures. Organizations also differ in terms of euthanasia policies. 

For anyone in the unfortunate position of needing to rehome a dog, one piece of advice we can take from this study is to go through a breed-specific rescue if possible, as these tended to have shorter waiting lists than places that take in dogs of all breeds/cross-breeds.

The study concludes that there is a sizeable population of un-owned cats and dogs in the UK. They say that “despite substantial quantities of manpower and money expended on these animals, it appears that at this time there is still a continual flow of animals out of ownership and into the guardianship of rescues and shelters.” 

The survey was conducted at a time of recession in the UK, which may have increased animal relinquishment, although a study in Chicago found only a slight difference. The problem is multifactorial, and it is likely that better education of pet owners, spay and neuter programs, campaigns for better provision of pet-friendly housing, and greater support for animal adoption would all help. You can read the results of a recent AHA survey on barriers to animal adoption here.
 
What do you think should be done to reduce the number of un-owned cats and dogs?

Reference
Stavisky, J., Brennan, M., Downes, M., & Dean, R. (2012). Demographics and economic burden of un-owned cats and dogs in the UK: results of a 2010 census BMC Veterinary Research, 8 (1) DOI: 10.1186/1746-6148-8-163

Wednesday, 17 October 2012

Behavioural problems in rabbits, rodents and ferrets

Many people keep rabbits, rodents and ferrets as pets. A study published last year by Normando and Galli (Padua University) is the first to investigate the kind of behavioural problems they have and how it affects owners’ feelings of satisfaction with their animals.

Participants were recruited via an Italian rabbit forum, the University of Padua, and local veterinary clinics. The survey was completed by 193 people about a total of 371 pets. The pets included 184 rabbits, 59 mustelids (mainly ferrets, but also including two skunks), and 128 rodents (including guinea pigs, hamsters, gerbils, chinchillas, rats and other rodents). 

Three different rabbits eating from a bowl
Photo: Oksana Shufrych / Shutterstock

Most owners reported no problems, but 29% of rabbit owners, 53% of mustelid owners, and 20% of rodents had a behavioural problem. For rabbits, the most common problems were inappropriate toileting, destructiveness, and not being cuddly enough. The most common problem with ferrets was being aggressive, followed by house-soiling and disobedience. For rodents, the main problem reported was not being sociable or cuddly enough.  

The questionnaire also asked about repetitive stereotypies, behaviours like chewing on the cage bars or pacing. Owner reports on this are hard to assess, since some behaviours might be alright up to a certain level, and only be problematic if they occur too frequently; the authors had to exclude a small number of reports. The analysis showed a link between the prevalence of stereotypies and the animal’s housing; pets with less freedom to roam were more likely to be reported as displaying a stereotypy.

In addition to the questionnaire, a subset of the animals were brought by their owners to the lab, to see how they behaved during a mock-up of the early stages of a visit to the vet. For the two skunks, the procedure had to be halted because the animal was aggressive, but most of the other animals performed well.

A curious ferret walking across a piano keyboard
Photo: grynold / Shutterstock
It’s interesting that even when the animals had behavioural problems, it did not mean that owners felt dissatisfied with their pet. This suggests the behaviour problems were not severe and did not interfere with the relationship. The owner had been bitten at least once by 96 of the animals, but this did not usually mean that the owner considered the animal to be aggressive. Aggression towards strangers was found significantly more often amongst the mustelids than the rabbits and rodents. 

Although owners had more complaints about mustelids, they also found them more satisfying as pets. This is perhaps because they are inquisitive and social animals, and so the owners find it more interesting to interact with them. However, it is also possible that people with many complaints would have rehomed their pet, and hence were not in the survey.  

The finding about stereotypies is consistent with what is known about laboratory animals, and shows the importance of an enriched and appropriate environment for the pet. 

Do you have a rabbit, ferret or rodent as a pet? If so, what do you like about it?

Reference
Normando, S., & Gelli, D. (2011). Behavioral complaints and owners' satisfaction in rabbits, mustelids and rodents kept as pets Journal of Veterinary Behavior,, 6 (6), 337-342 DOI: 10.1016/j.jveb.2011.01.005

Wednesday, 10 October 2012

CAWC report on shock collars

In September, the UK’s Companion Animal Welfare Council published a report on the scientific evidence on the use of shock collars in dog training. They use the term ‘electronic pulse training aids’ or EPTAs, because the collars do not necessarily induce a ‘shock’ but may sometimes be used only to induce a tickling sensation. I will use the everyday term here. The report included the use of collars as a training aid as well as invisible fences designed to administer an electric current if the dog crosses a boundary.

The independent review was chaired by Professor D.S. Mills, and looked at the scientific evidence, accepted submissions from interested parties, and undertook a small-scale survey of their use in the UK. The ten peer-reviewed studies discussed in the report looked at the use of shock collars for a surprisingly wide range of behaviours, including chasing, barking, and preventing acral lick dermatitis (‘hot spots’). The report discusses many problems with the literature. For example, one study which found the shock collar to be effective in preventing hot spots only included 5 dogs; a further 5 had to be excluded because the owners – although willing to use the collar – were unwilling to use it in the way required for the study. The report is to be commended for the thorough way in which these studies are discussed.

Boxer puppy wearing shock collar
The report says there is an "unnecessary risk to animal welfare in the unregulated availability of the current range of devices"
Photo: Charlene Bayerle / Shutterstock

The question is also a moral and ethical one. The report received submissions from both sides of the debate, and says each side believes it has animal welfare at heart. The typical argument of those in favour of their use is perhaps that of stopping chasing and therefore preventing a dog from being shot for harrying sheep. However, the report points out that in this case, a lead could be used instead. Each argument for-or-against the use of shock collars is considered.

An internet survey of the use of shock collars collected responses from 188 people. 8% were using EPTAs on cats, mainly to prevent straying. The remainder were used on dogs, mainly for obedience but invisible fences were also used. The report estimates that there are 350,000 EPTAs in the UK.

The report concludes that there is not enough scientific evidence to say whether shock collars are effective or not, but there is evidence that if mis-used they can cause harm. They suggest that if the UK Parliament decides to continue to allow their use, a number of safeguards should be implemented, including a requirement for users to be licensed, a warning signal (conditional stimulus) to be made prior to the electric shock, the ability to cancel the shock if the warning signal elicits the required behaviour, and some kind of visible or other warning for invisible fences. They also say that if a dog is barking out of distress, use of an anti-barking collar would be inappropriate, since it will not resolve the dog’s distress.

One study that I was surprised was omitted is that of Meghan Herron et al. Herron’s study of dogs that had been referred for behavioural problems found that 7% were reported to have an aggressive response to use of the shock collar. In fact, the CAWC report does not clearly explain how studies were identified and chosen for inclusion. Presumably Herron’s paper wasn’t considered because the working group excluded survey designs; this is surprising since they included case studies and conducted their own brief survey. The CAWC report already acknowledges that shock collars have the potential to cause harm, so the inclusion of Herron’s study may not have changed their findings. However, Herron's study does suggest a potential risk to the owner, as well as to the dog.

The wider evidence on positive vs negative reinforcement in dog training was not considered, because it was beyond the group's remit. Many surveys have found that owners who use positive reinforcement only have better behaved dogs. If you’d like to know more about these studies, I wrote a series here.

The report alludes to future studies that will directly compare shock collars to other methods, and says its findings must be considered in the light of this research as it becomes available. Shock collars are already banned in Wales; it remains to be seen what UK Parliament will decide.

The full report is 92 pages and you can read it here.

Are shock collars and invisible fences legal where you live?

Reference:
Companion Animal Welfare Council (2012) The use of electronic pulse training aids (EPTAs) in companion animals. Available online at cawc.org.uk.

Wednesday, 3 October 2012

Canine Neuroscience

The main problem with the neuroscience of dogs is that they would have to be sedated to be in the scanner, and then their brain wouldn’t be doing its normal stuff. Until now.

A team of scientists led by Gregory Berns at Emory University has successfully trained two dogs to go into the fMRI scanner and keep still long enough for a brain scan. Prof Berns says he got the idea from realizing what military dogs are trained to do – if a dog can parachute out of a plane with its handler, he thought, then surely it could do an fMRI.

The dogs are Callie, a two-year-old feist (small hunting dog), and McKenzie, a three-year-old border collie. And while McKenzie does agility, Callie had only had basic obedience training, and is a rescue dog. (If anyone ever tries to say negative things about rescue dogs, tell them about Callie!).

Dogs can haz brainscanz?

The dog training was complex and took place over several months. A mock-up of the scanner was made for each dog, including a replica head coil, a tube of the same size as the real thing, and a patient table within the tube with a head rest for the dog. Because dogs’ hearing is so sensitive, they also had to learn to wear headphones to protect their ears. The first times the scientists actually started the scan, the sound caused a startle reaction, so they played the sound throughout the training sessions to get the dog used to the noise that the machine makes.

The dogs were trained using positive reinforcement, and had to lie still with their head in a chin rest. Once the dog was used to this, the chin rest was moulded to give a custom fit, because it’s important for the dog’s head not to move in order to allow the scan to be interpreted. Finally, they were ready for the real thing.

What task was used for this ground-breaking experiment? The researchers wanted to know if there is a different pattern of activity in the brain when the dog sees a hand-signal that means their owner is about to give them a treat, compared to when they see a hand-signal that means no treat. The hand signals were left hand held up to mean the dog was about to receive a piece of hot dog, and both hands pointing horizontally to each other to mean no hot dog was forthcoming.

The dogs were trained on this task for ten minutes a day for several weeks prior to the actual experiment. The dog had to hold still for ten seconds while the hand signal was made, and then if it was the ‘treat’ signal the owner reached into the scanner to deliver some hot dog; the dog could move to get the treat and then had to go back into position.

Seven border collies posing for a group photo
Do you think these border collies are anticipating a reward?
Photo: Ksenia Rayknova / Shutterstock

Previous work on people and monkeys has shown that the caudate region of the brain is activated in expectation of a reward. The scientists found activation in the ventral caudate region of the dogs’ brains in response to the hand signal that denoted a treat, but not for the other hand signal; this shows the dog had learned to expect a reward.

This study is exciting because it demonstrates that canine neuroscience is possible. A future study might look for any differences in activation depending on whether it is the owner or someone else who makes the hand signal. This would tap into the same wider debate as that considered by Feuerbacher and Wynne in their investigation of whether dogs and wolves prefer treats or social interaction as a reward. 

The experiment was conducted with great care for the dogs’ wellbeing and they were free to exit the scanner at any time. The researchers make some useful comments about the ethics of this kind of study; for example, they say it wouldn’t be appropriate to use laboratory-bred dogs as they would have no choice whether to take part in the experiment. 

Emory University made a short video about the research which you can see here.

If you could train your dog to go in an MRI scanner, what would you test?

Reference:
Berns GS, Brooks AM, & Spivak M (2012). Functional MRI in awake unrestrained dogs. PloS one, 7 (5) PMID: 22606363

Wednesday, 26 September 2012

Getting a puppy? Ask to see both parents

When you're getting a puppy, it's best to see both parents if possible, according to a new study.

A Rottweiler mother suckles her cute puppies on the lawn


When people get a puppy, a standard piece of advice from many dog welfare organizations is that you should always ask to see the mother. This week, I’m reporting on a new piece of research that investigates whether or not this is good advice.

The study, by Carri Westgarth of the University of Liverpool, UK, was designed to find out if there is a link between behavioural problems, the age of acquisition of a puppy, and whether or not the owner had viewed the mother and father of the puppy before they brought it home.

It has long been suggested that improper welfare of the mother causes behavioural problems in puppies, and that seeing the mother is one way to ensure that the puppy is being raised in an appropriate environment. (See here for research on the long-lasting effects of puppy mills on breeding dogs).

The study was designed carefully to ensure that other factors – such as the likelihood of an owner seeking behavioural help – would not influence the findings. To do this, members of the Association of Pet Behaviour Counsellors were recruited to identify participants that had been referred for a behavioural problem. These dogs were called the ‘case’ dogs.

Another set of dogs, the controls, were identified from the same veterinary practices that the case dogs came from; this was done so that they would match the case dogs as closely as possible, except that they had not been referred for a behavioural problem. The dogs chosen were ones whose owner probably would refer them if a behavioural problem arose. Both groups of dogs included pedigrees and mutts, and they were fairly closely matched for the type of dog (i.e. hound, gundog etc).

The most common behavioural problems were aggression towards people or towards other dogs. The average age of the case dogs was 2, and of control dogs was 5. This is not surprising, because adolescent dogs are more likely to be referred to a behaviourist. Both sets of dogs were equally matched for neuter status, with 28% being entire and the remainder neutered/spayed.

Puppies that were acquired at 6, 9 or 10 weeks were less likely to have been referred for behavioural problems than those acquired at 8 weeks. This is surprising, although some other studies have found that puppies homed at 6 weeks are less likely to have problems later. It could be that being rehomed earlier allows more time for socialization during the optimal period, but it could also be that if a puppy is in a bad environment (such as a puppy farm) it’s better to remove it at the earliest possible opportunity. No definite conclusions about the best age to get a puppy can be made from this study.

The headline finding is that if people had seen only the mother, the puppy was 2.5 times more likely to be in the case group rather than the control group (i.e. to have behavioural problems). If the owner had not seen either parent, the puppy was 3.8 times more likely to have been referred for a behavioural problem.

Amongst those people who had not seen either parent, reasons that were given included the puppy being brought to their home, the puppy already being in a second home at the time they got it, or they met the breeder at a hotel or some other location. These are all potential signs of a puppy mill, since puppy farmers can go to great lengths to disguise where their puppies come from.

Hence, in many of these cases where people did not see either parent, it is likely the puppy did not originate from a responsible breeder, although we cannot assume that this was always the case. Having said that, it sometimes happens that seeing the mother in a less-than-suitable environment doesn’t put people off acquiring a puppy; I know anecdotally of cases where people have still wanted it, often due to a stated desire to ‘get the puppy out of there’. It would be interesting for future research to follow people through the process of acquiring a puppy to learn more about their decision process.

Westgarth’s study was a retrospective one, looking back at how people had acquired their puppy. It’s possible that people who are better educated about puppy mills also have better knowledge about how to bring up a puppy, and so are less likely to bring up a dog with problems. Nonetheless, the finding is striking.

It is sound advice to say that prospective puppy owners should always ask to see the mother, and even better if they can see the father too.

What's your advice to someone looking to get a puppy?

Reference
Westgarth C, Reevell K, & Barclay R (2012). Association between prospective owner viewing of the parents of a puppy and later referral for behavioural problems. The Veterinary record, 170 (20) PMID: 22562104
Photo: Stephen Coburn (Shutterstock.com)

Wednesday, 19 September 2012

Now where’s my treat?

A study tests whether dogs and hand-reared wolves prefer food or social interaction as a reward.

Trainers often advise owners to use treats to train their dogs, but some owners want to phase them out as fast as they can. Shouldn’t a dog be prepared to work for just verbal praise and affection? That’s the question asked in a recent study by Erica Feuerbacher and Clive Wynne – and they didn’t just test dogs, but wolves too!

A brindle boxer is happy to receive a treat
Photo: LarsTuchel / Shutterstock

The question is interesting for practical reasons, since it’s useful to know how to motivate a dog if you want to train one. But it’s a very interesting question for another reason too. Some scientists have suggested that dogs are uniquely tuned in to human contact; in other words, that in the process of evolving from wolves, dogs have developed special abilities to read human emotions and communication. If this is the case, then social contact with humans should be a valuable reward in training sessions with dogs, but not wolves.

The study involved five separate experiments, four with dogs and one with hand-reared wolves. Two different types of dog were included: those who lived in homes with their owners, and those in a shelter. It might be expected that shelter dogs, starved of the usual amount of human contact, would respond especially well to social interaction as a reward. On the other hand, if a relationship with someone is needed for that interaction to be valuable, dogs with owners would respond more.

The experiments all used the same task: a simple nose-touch to the hand. In the food condition, the dogs and wolves were rewarded with a small piece of food. For the dogs, it was a piece of Natural Balance (except for one dog with allergies, who was given a small piece of potato instead). For the wolves, it was a small piece of sausage, because this is what the wolf trainers recommended.

In the social condition, dogs were rewarded with 4 seconds of social contact – petting either side of the head combined with verbal praise. (One of the wolves did not like physical touch, so he just received praise). This is only a short time of social interaction, but the length of time it took coincided with the length of time taken to give a treat.

If the dog or wolf touched the experimenter’s hand, the hand was removed to shoulder height and then the reward was given (food from the other hand or the social interaction). For the owned dogs, the owner carried out the experiment, and for the wolves at Wolf Park, a trainer did the experiment in each wolf’s pen, with another trainer present for safety reasons.

The results showed that across all three types of animal – shelter dogs, owned dogs, and wolves – food was a better reinforcer than social interaction. Although there were individual differences between animals, the use of social interaction as a reward did not lead to many nose touches. On the other hand, when food was used as a reward, many more nose touches were recorded, and the time interval between them was shorter.

The wolves did more nose touches than the dogs, and in fact the best performing wolf produced 33% more nose touches than the best performing dog. It’s not known if this is because of a wolf’s greater intelligence, or because they had some prior training that was useful (but some of the owned dogs had also had relevant prior training from their owners in their normal lives).

The results are fascinating. Instead of suggesting that dogs have developed special abilities to understand humans, it seems that our special relationship might come about because of ongoing reinforcement. The authors say, “…domestication has not necessarily resulted in dogs being more sensitive to human behavior than wolves. The comparison with wolves confirmed that the relative effectiveness of social interaction for hand-reared wolves was the same as for dogs.”

Of course, only a brief period of social interaction was used in this study, and it might be that longer periods would work better. If this were the case, though, I would have expected the dogs to nudge the experimenter to ask for more fuss. And while the food reward for the wolves was sausage, which might be a better motivator than the treat given to the dogs, it’s still the case that social interaction did not really motivate the wolves or dogs.

So next time someone says they want to phase out treats in dog training, this study provides evidence that it would be a good idea to stick to the treats after all.

If you want to know more about how to use food to train your dog, check out my article on positive reinforcement in dog training.

From your dog’s point of view, what’s the best reward in a training session? For my dogs, sausage is definitely a favourite.

Reference
Feuerbacher EN, & Wynne CD (2012). Relative efficacy of human social interaction and food as reinforcers for domestic dogs and hand-reared wolves. Journal of the experimental analysis of behavior, 98 (1), 105-29 PMID: 22851794

You might also like: 
Do dogs prefer petting or praise?
The importance of food in dog training
How do hand-reared wolves and dogs interact with humans?
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