13/02/2022
Lengthy post but well worth a read.
On the Rebound
🐎There’s a specific class of behaviours that causes horse owners no end of worry and trouble, but they’re not always recognised for what they are. They’re called “rebound behaviours” (or sometimes, ‘post inhibitory rebound”. Horses, like us and many other animal species, have drives related to things that are essential for life. These drives are very strong urges, and while animals can temporarily suppress them, the need to perform them then starts to build up pressure like water behind a dam. I’m going talk about the ones that most often affect how well we can care for and handle our horses, ponies, donkeys and mules.
Firstly and most commonly experienced, movement rebound behaviours. Even humans are designed to move a specific amount, and if for any reason we’re not able to move, the need to do so becomes very strong. Imagine a school full of children in classes - when they hear the bell that tells them it’s break time, they’ll spill out of the school into the playground and find various ways to move around until the need to move that’s been building up all through the time they’ve been sitting still concentrating is satisfied.
🐎Horses are animals who have evolved to move almost constantly. There is a specific part of the brain that is dedicated to movement, and that brain pathway also deals with some aspects of what animals find rewarding. In many cases, rewards are obtained through movement, and movement is satisfying and rewarding both in its own right and in terms of what it can help the animal gain.
Situations where movement rebound may become an issue include having a horse on box or stall rest, but also where a horse is stabled for long hours during winter months or when weather conditions mean a horse living out doesn’t move around so much. Going back to the idea of water held behind a dam: if the water constantly escapes at a given rate, the pressure stays at a constant level. Even a tiny trickle of water helps relieve the pressure against the dam. However if the water builds up due to a blockage, once it escapes the torrent of water can sweep everything before it. A horse who’s been unable to move normally is unlikely to walk slowly and calmly out of their stable. Lack of ability to move causes frustration, and the horse will often explode into motion. When the opportunity to fulfil a frustrated drive happens, the behaviour that follows will be more intense than the way the horse expresses that behaviour under normal circumstances.
🐎Eating is another behaviour that’s subject to post inhibitory rebound. Horses are trickle feeders : their digestive system means they should forage almost constantly - through the day and night, through the four seasons - for low value food. Horses are able to thrive in places like Mongolia where they have to work hard to find forage in some seasons. They are a species well suited to challenging environments.
🐎In contrast, we provide them with copious amounts of forage and find they become fat: so we find ways to restrict their access to forage. The desire to seek out food and eat is strong, and if it’s frustrated, rebound eating can cause us all kinds of issues. As soon as the horse has the opportunity to graze or eat following restriction, they will eat continuously without pause for a much longer period than normal. Ponies in “starvation paddocks” are motivated to escape to find more food, and they can eat huge quantities of grass in a short time. Horses who have been wearing grazing muzzles will eat for longer periods of time and consume much more in a given time period once the muzzle is removed.
🐎There’s a whole range of social behaviours that horses appear to have a strong need to perform. Horses who have been housed singly will show a rebound of intense play behaviour once allowed the opportunity. This can pose a problem for owners who see kicks and bites: because the behaviour is more intense following deprivation, the horses don’t hold back the way they do when these behaviours are part of their day to day life. There’s also evidence of rebound in social grooming behaviour. These behaviours are often not taken into account in equid management. Individual turnout paddocks have become very popular and owners don’t realise that social contact is not a nice add on: it’s something that can result in a frustrated need, leading to less relaxed horses.
🐎Sleep behaviour is also subject to rebound. Horses whose sleep is interrupted for any reason, including travel or a move to a new home, may show rebound sleep once they eventually feel safe enough to lie flat. In the meantime, owners often miss why their horse is off form, not realising that the horse is sleep deprived and that ability to attend and learn is affected by lack of sleep.
🐎Finally, horses, like all animals, have a strong desire to reproduce. Although this does still affect geldings to a small extent, it is often a noticeable issue in mares who don’t have the opportunity to find a mate. We deliberately inhibit a mare’s chance to find a stallion, so with every season she experiences, the urge to mate becomes stronger. Horse, pony and donkey owners are often surprised when a mare comes into season when a new gelding moves in. What they don’t realise is that the mare sees a new male horse: she has no way of knowing that while he may have a liking for the company of mares, he may have no desire to mate. These seasons are often - like other rebound behaviours - very intense and they may affect the mare’s exercise programme and how easy she is to handle.
🐎What’s the best way to deal with rebound behaviour? Try to prevent it! Find ways to allow the water in the dam to flow. Find ways to allow the horse on box rest limited movement. Find ways to allow food restricted horses to forage for short periods. Find ways to allow socially deprived horses to have small amounts of social contact. For the most part, though, the important thing is to understand the way our chosen management impacts on the horse, pony, donkey or mule in terms of their NEED to perform specific behaviours. Good management allows the expression of natural behaviours, and this is enshrined in the Five Domains model of animal welfare.
Have you observed any rebound behaviours in your horses, donkeys, mules and ponies? I can think of a few that I haven’t mentioned!
Bertone, J. J. (2015). 10 Sleep and Sleep Disorders in Horses. Equine neurology, p.125..
Ladewig, J., Søndergaard, E., & Malmkvist, J. (2002). Effects of individual versus group stabling on social behaviour in domestic stallions. Applied Animal Behaviour Science, 75(3), 233-248.
Davis, K. M., Iwaniuk, M. E., Dennis, R. L., Harris, P. A., & Burk, A. O. (2020). Effects of grazing muzzles on behavior and physiological stress of individually housed grazing miniature horses. Applied Animal Behaviour Science, 231, 105067.
Freire, R., Buckley, P., & Cooper, J. J. (2009). Effects of different forms of exercise on post inhibitory rebound and unwanted behaviour in stabled horses. Equine Veterinary Journal, 41(5), 487-492.
Mellor, D. J., & Burns, M. (2020). Using the Five Domains Model to develop welfare assessment guidelines for Thoroughbred horses in New Zealand. New Zealand veterinary journal, 68(3), 150-156.
