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Dr. Paul McGreevy on Horse Behavior
WRITTEN BY: RIRDC Equine Research News   [March 1996]

Dr. Paul McGreevy is a veterinarian who graduated from Bristol University in 1987. Following graduation, Paul worked in mixed practice for 3 years and in equine practice for 2 years after which he did a PhD in horse behaviour at Bristol which was completed in 1995. In January 1996 he took up a position as Lecturer in Animal Science at the Veterinary School, University of Sydney. In this interview he discusses issues of horse behaviour with the Equine Program Manager, Prof. Reuben Rose.

Q: What led to your interest in studying horse behaviour?

A: I have had horses all my life and I have always enjoyed just sitting and watching them interact. When I was studying to become a vet I realised that there is very little in the scientific literature on the study of equine behaviour.

Q: What are the methods of studying horse behaviour and why is it important to study?

A: The methods include looking at feral horse behaviour and comparing it to what we see in domesticated and stabled horses. We can then use these comparisons to evaluate what may be abnormal behaviour.

Q: Is it important to differentiate between the behaviour one would expect in natural conditions and the behaviour under unnatural conditions?

A: Yes, thatís right. Any departure from the home range grazing system, which is how feral horses exist, can have repercussions on behaviour and we need to understand the changes in order to manage our horses successfully

Q: Where does one study feral horse behaviour and how can we be sure that this is the norm?

A: Itís an interesting question because purists would argue that there is no such thing as a wild horse any longer. The Przewalski horse has in a sense been domesticated since the 1950ís when the horses were retrieved from the wild before extinction. So now our closest approximation to wild horse behaviour is seen in feral horses that are free ranging. These types of herds include Brumbies, New Forest ponies, Mustangs and Assateague ponies.

Q: From what has been described, what are some of the key features of feral horse behaviour compared to horse behaviour under domesticated conditions?

A: There are two important factors that influence feral horse behaviour: Social organisation and the nature of the home range. The home range is the area that the horse covers in its search for food and water. Distances covered each day depend on the location and the availability of these key resources. If weíre talking about a domestic situation, the horse is in a very intense environment, where water is close at hand and food is readily available in a concentrated form. This type of environment is far removed from that of free ranging horses. A concentrated ration can be consumed in two or three hours whereas the horse has evolved to graze for 16 hours a day.

Q: So there are very big differences between how much time they spend exercising and eating. Is there an average distance and speed that a feral horse might travel in one day?

A: No, because it depends on the size of the home range and the quality of the forage. Meanwhile social organisation depends on herd size which has been shown to vary with population density. Home ranges incorporate grazing sites, waterholes, shade, windbreaks and refuges from insects and can vary in area from 0.9-48 square kilometres. As far locomotion behaviour is concerned, horses have been shown to travel on open ranges to water holes up to 65-80 kilometres in a day. Where horses are managed at pasture, grazing is the main initiator of locomotion and the distance they cover has been estimated at 20 kilometres per day. So, the distance a grazing horse travels can depend on the location of water, the availability of food and time that is spent foraging.

Q: To summarise some of the major differences, we have domesticated horses spending perhaps only 15% of their time eating versus 75% seen in feral horses and on average much less of the day is spent walking or exercising.

A: Yes, and we also isolate horses which means that they have very different social patterns.

Q: Has the social interaction of horses been examined in different environments?

A: The way horses behave as a group is currently an interesting and popular research topic and therefore the importance of social behaviour is becoming more clear. For example, the "allogrooming" behaviour with which we are all familiar, where two horse groom each other, has been shown to reduce heart rate. So itís not just simply a grooming matter, it has a more important consequence in terms of stress reduction. There are a number of management systems being designed and used around the world that address the need for the horse to exist as a social animal. The problems that are inherent in the designs of medium density housing for horses are to do with the control that we have over the amount of food that they consume and how they fight to access that ration. Even in traditional loose boxes, we now see stable designs that allow neighbouring horses to see and touch one another, for instance through bars and grilles between stables.

Q: What are the main types of abnormal behaviour that one sees as a result of abnormal social situations?

A: We know that abnormal behaviour arises in management systems that reduce social contact but we canít be certain that there is a specific cause and effect as far as social behaviour is concerned. We donít know that the reduction of social interaction directly cause equine behaviour problems.

Q: What is generally regarded as abnormal behaviour?

A: We are talking here about what used to be called "vices". That was perhaps an unfortunate term because it implied that the horses were somehow to blame for their behaviour. The types of abnormal behaviours that we generally see in the stabled horse include stereotypies like crib-biting, wind-sucking, weaving, box walking and possibly redirected behaviours such as wood chewing and bed-eating. These have been called stress-coping mechanisms.

Q: Because we donít know what is normal behaviour in the horse, how do we know if a particular behaviour is normal or abnormal?

A: It's a philosophical point. However, because horses evolved to be free-ranging, we can say that behaviours that do not appear in feral horses are probably abnormal.

Q: Are some of these behaviours learned?

A: It's a very interesting area because although we commonly assume that horses copy these behaviours, this assumption could be fallacious. These horses are under the same management as their neighbours and so it could be the management or the stable design thatís causing them to adopt a stress coping mechanism. Beyond that, mimicry has yet to be shown in any behaviour by horses. There is also the possibility that the sight of another horse crib biting or performing any stereotypy is a stress in itself and that could be whatís going on when the prevalence of stereotypic behaviours start to rise in a yard.

Q: So theyíre not copying, theyíre being stressed by the sight of the behaviour and thatís producing the same stress coping mechanism as an outcome?

A: Yes, thatís one possibility.

Q: Could you tell us a little about how you study horse behaviour?

A: We use time lapse photography so that a 24 hour time budget can be established for a group of horses. We do our best to be out of sight when these sort of studies are going on because we realise that there is a possibility of an operator effect. We also measure the heart rates of the horses and look at various measurements in the blood while theyíre performing different behaviours, to see if we can see a correlation between the behaviour and perhaps a reduction in the stress index. We also look at food and water intake in tandem with the time budget that weíre examining on the video.

Q: How do horses generally spend their day in the stable environment?

A: That very much depends on their diet, exercise regimen, turn out time and whether they have the opportunity for social interaction.

Q: Lets take an average situation, say a horse in training that may spend an hour out of the stable and is fed morning and afternoon. How does that horse generally spend its day?

A: In general that depends on the roughage content of the diet. Once he has eaten his ration, the stabled horse will spend his time loafing which is a rather inert behaviour. In isolation, he cannot play so he will either loaf or sleep. Interestingly, there is a correlation between the content of oats in the diet and sleep. In tests, ponies spend 20% more time loafing when oats replace hay in the ration.

Q: If we take two extremes, say horses on a complete roughage diet versus a performance horse with essentially a grain diet with small amount of roughage, what are the major behavioural impacts of the dietary difference?

A: The intensively managed horse receiving concentrated food is limited in his ration so it will eat its ration quickly and will tend to have so-called vacuum periods whereas a horse with a full net will revisit and pick away filling its day that way. An intensively managed horse is more likely to be frustrated by having nothing to do and therefore may adopt a stereotypy such as crib biting, wind sucking weaving etc.

Q: Youíve done a number of studies in different groups of horses. In what management systems did you see the highest incidence of these behaviours?

A: Taking all of these behaviours together, the risk of a horse performing an abnormal behaviour is increased under a number of circumstances. We actually looked at 22 different yards and 5 management factors were found to be important. Firstly, if the amount of forage per day fell below 6.8 kilos we saw a rise in abnormal behaviour. When bedding types other than straw were used, we saw an increase in abnormal behaviour. When the total number of horses in the yard was fewer than 75 we saw a similar increase and there was also an association with box design; that is, the less box designs allowed contact with neighbouring horses the more abnormal behaviour was shown. When a variety of forages were used instead of hay alone we saw a reduction in abnormal behaviour. A second study showed that time spent in the stable was another important risk factor.

Q: Can we assume that if we see an abnormal behaviour, the horse is under some stress?

A: No, we know that once they have developed, these stereotypies can persist even in horses that are no longer stabled. In another study, we showed no correlation between the removal of the opportunity to perform these behaviours and a rise in stress measurements. However, we did find that stereotypic horses had higher stress levels to start with, even in the paddock.

Q: In terms of the future, where do you see these sorts of studies going and what do we need to know that will help us?

A: As the science of animal behaviour and animal welfare matures we will define stress and frustration more accurately. We will also refine non-invasive techniques for measuring stress hormones like cortisol. By changing the various management regimens and reducing stress we can expect improvements in disease resistance and possibly therefore performance. Obviously there are good reasons for stabling horses, but we need to arrive at a more refined compromise between the traditional practices of owners and the evolutionary needs of horses.

Q: In general do you have advice for people if theyíve got a high incidence of the abnormal behaviours in horses?

A: Yes, probably they should consider ways in which they could re-appraise their management practices. Specifically they could look at the way the forage is presented and how foraging time could be increased. For instance, you can make horses work harder to get forage out of a hay net by having a net with smaller holes. Increasing the social contact between neighbouring horses will also be helpful. The other obvious one is to try to get the horse out of the box as much as possible.

Reprinted from the RIRDC Equine Research News with the permission of the Rural Industries Research and Development Corporation.

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