Equine Behaviour[edit | edit source]
Horses are preferential grazers and, in the wild, have adapted to live life on open plains or mountains. They are, however, adaptable to environmental challenges and can live in other areas. Studying feral or free-ranging horses provides insight into the behaviour of domestic horses. In particular, it highlights that most adaptive equine behaviours have not changed much during 6000 years of domestication.
Horses typically live in herds and the behaviour of each horse helps to achieve stability within the group. Being a member of a group is essential to the horse's survival in the wild, so members of a herd behave in such a way as to minimise inter-group conflict. The following features are typical of a herd that has a stable social structure:
- There is an avoidance of conflict
- Hierarchical relationships are not often reinforced
- Aggression tends to be caused by competition for limited resources (this is more pronounced in domestic horses than feral horses)
- Changes in herd membership cause instability
Equine Communication[edit | edit source]
Horses communicate mostly through visual communication. Other methods of equine communication include vocalisation and the use of odour and touch. Horses are very sensitive to the body language of other horses. They also generalise their communication to humans and are able to react to changes in our body language. They are, therefore, responsive to human stress signals. While horses are usually perceived as a "social prey species" whose survival depends on fleeing from predators, horses may respond to predators with defensive behaviour when they are unable to flee. They will communicate their response to threats in the following ways.
Aggressive threat signals in horses:
- Initially, the horse will provide subtle signals such as nose wrinkling and ear flattening
- These signals escalate to head jerks, baring teeth, stomping a front leg, charging, and ultimately biting
- Direct attacks might appear to come out of nowhere, but they are often actually a learnt response to humans who do not respond to the horse's more subtle aggressive threat signals
Defensive threat signals in horses:
- The horse will also begin with mild signs like nose wrinkling and ear flattening
- These signs progress to the horse using its body to block approaches, flattening its tail and presenting its rump, raising a hind leg, backing up and, finally, kicking with one of its hind legs
Feeding[edit | edit source]
Food and fodder placement can have a significant impact on a domestic horse's physical health. The following table provides a summary of the benefits and disadvantages of types of food and fodder placement.
|Hay net||Only a small amount of waste||Forces horse into an unnatural head and neck position when it is placed too high
A horse's foot might get stuck if it is too low
The horse is at risk of upper respiratory tract irritation from dust and seeds
|Hay bag||Only a small amount of waste||Forces horse into an unnatural head and neck position|
|Ground||Natural spine position||High amount of waste
Risk of sand colic
|Haybar||Natural spine position||Only a small amount of waste|
Equine Body Condition Scoring[edit | edit source]
Using the equine body condition scoring system gives an indication of a horse's overall health. This system was described in 1983 by Henneke and colleagues. The full scoring system is provided here. The following video provides examples of horses being scored.
Basics of Equine Nutrition[edit | edit source]
The equine digestive tract has a fore gut and hind gut:
|Type||Fore Gut||Capacity||Percentage of gastrointestinal tract|
|Enzymatic digestion||Stomach||8 – 15 litres||8%|
|Duodenum, Jejenum, Ileum (21 metres)||68 litres||30%|
|Microbial digestion||Caecum (1.2 metres)
Large colon (3 – 3.6 metres)
Small Colon (3 – 3.6 metres)
|28 – 36 litres
The following video provides a summary of the equine digestive system.
Horses are non-ruminant herbivores (i.e. hind-gut fermentors) and typically spend around 16 hours a day grazing.
It is important to note that the equine stomach is not designed to process large volumes of food. Horses have a small stomach, with limited feed intake capacity. Any horse who is being given large volumes of hard feed (i.e. grains) needs to be referred to a veterinarian or equine nutritionist. The stomach initiates the breakdown of food by secreting hydrochloric acid and pepsin.
Because horses do not have a gall bladder, it is difficult for them to digest high-fat diets. Thus, a normal equine diet will only contain around three to four percent fat.
Most digestion of nutrients and absorption of vitamins and minerals occur in the horse’s small intestine.
The caecum (beginning of the large intestine) has various functions:
- Liquids mostly pass through to here
- Detoxification of toxic substances
- Contains protozoa and bacteria that digest fibre and soluble carbohydrates in the small intestine
The large intestine (large colon, small colon, and rectum) has four parts:
- Right ventral colon
- Sternal flexure to left ventral colon
- Pelvic flexure to left dorsal colon
- Diaphragmatic flexure to the right dorsal colon
Impaction is common in the sternal and diaphragmatic flexures.
Water[edit | edit source]
Water is the most important nutrient in a horse’s diet. Signs of a lack of water include:
- Decreased intake of food and physical activity
- Typical signs of dehydration such as:
- Dry mucous membranes in the mouth
- Dry faeces
- Decreased capillary refill time
Water deficiency may be due to a general lack of a water source, accessibility (if it is frozen or contaminated), palatability, or illness.
Energy[edit | edit source]
Energy is not a specific nutrient, but it is necessary for life. Signs of energy deficiency in horses include weight loss, decreased physical activity, reduced milk production and growth rate. However, horses who take in too much energy, may become obese and are at greater risk of colic and laminitis. They also experience more sweat loss and decreased exercise tolerance.
Fat[edit | edit source]
Fat contains three times more energy than grains or carbohydrates, so when it is added to feed, greater energy is available for the horse. Most premixed feeds usually contain 2 to 6 percent fat, but this can be as high as 10 to 12 percent fat. 
Carbohydrates[edit | edit source]
Carbohydrates are the main energy source in most equine feeds. Horses easily break down and absorb soluble carbohydrates such as starches and sugars to glucose in the small intestine. Insoluble carbohydrates such as fibre are fermented by microbes in the large intestine.
Soluble carbohydrates are present in most types of horse feed (particularly corn, barley and oats). Forages typically contain 6 to 8 percent starch, but some may be up to 30 percent starch. It should be noted that the sudden consumption of large amounts of starch / sugar can lead to colic or laminitis.
Protein[edit | edit source]
Protein is essential for muscle development, either during growth or exercise. Amino acids are the main building blocks of protein. Adult horses typically require 8 to 10 percent protein in their diet, but lactating mares and foals require more.
Signs of protein deficiency in horses include:
- Rough or coarse hair
- Weight loss / reduced growth
- Decreased milk production
- Reduced performance
Conversely, excess protein can cause:
- Increased water intake and urination
- Increased sweat loss during exercise (leading to dehydration and electrolyte imbalances)
Vitamins[edit | edit source]
Vitamins are either fat-soluble (vitamin A, D, E, and K) or water-soluble (vitamin C, and B-complex). Horses usually consume adequate levels of vitamins if their diet includes fresh green forage and / or premixed rations. However, supplements may be needed if horses are:
- Receiving high-grain diets
- Receiving low-quality hay
- Stressed (e.g. travelling, showing, racing)
- Involved in prolonged strenuous activity
- Not eating well (due to illness etc)
Minerals[edit | edit source]
Minerals are necessary for:
- Body structure
- Fluid balance in cells
- Nerve conduction
- Muscle contraction
Horses only require small amounts of macro-minerals (e.g. calcium, phosphorus, sodium, potassium, chloride, magnesium, and sulfur) daily.
The following table summarises the role of specific minerals:
|Fertility||P, Cu, Zn, Se, Mn|
|Bone development||Ca, P, Mg, Mn, Cu|
|Muscle development||P, S, Zn, Se|
|Milk production||Ca, P, Mg, Zn|
|Skin and claw health||Zn, Cu, Mn|
|Hair coat||Cu, Zn, Se|
|Disease resistance||Cu, Zn, Mn, Se|
|Foetal development||Cu, Zn, Mn, Se|
|Nervous system||Mg, P, Cu|
|Appetite||Mg, K, Zn, Cu|
Stable Floors and Bedding[edit | edit source]
Horses often spend a significant amount of time in their stalls, so specific aspects of flooring should be considered, including:
- Its shock-absorbing qualities (to reduce stress on the horse's joints when it moves or gets up from lying down)
- If it is non-slip (to reduce the risk of a horse injuring itself when it gets up)
- If it is hard-wearing so that it remains level (to reduce the risk of a horse developing postural strain syndromes)
The following table, adapted from Fabian, assesses a number of flooring materials for the above qualities.
|Shock absorption||Non-slip||Hard wearing|
Turnout (Paddock Time)[edit | edit source]
Turnout or free exercise time has been found to have positive effects on horses' behaviour. The following table summarises some of the advantages and disadvantages of different durations of turnout time and sizes of paddock:
|Size of the paddock||Advantages||Disadvantages|
|Small||Less risk of injury||Less free movement, which affects:
|Large||Encourages constant movement||May increase injury risk|
|Separated from other horses||Reduces risk of injury||Psychological isolation may increase stress
Low stimulus for movement
|Amount of turnout time|
|Restricted||Reduced risk of injury||May increase stress
Low stimulus for movement
|Most of the day||Encourages free movement||May increase injury risk|
Reducing Stress in Horses[edit | edit source]
Stress has been found to have an impact on farm animals’ growth, production, reproduction and susceptibility to disease. Chronic exposure to stress and the associated ongoing release of cortisol negatively impacts immunity, digestion, behaviour, reproduction and the cardiovascular system. Similarly, animals may develop gastric ulcers, colic, and diarrhoea when exposed to stress. The following factors can increase stress in horses.
Improper feeding[edit | edit source]
In the wild, horses move and graze. In fact, feral horses spend 70 percent of their time grazing. If a horse is not on pasture, it is recommended that it be fed at least four times a day at regular intervals. However, if high energy feeds are given inappropriately, this can, in some cases, increase stress.
Lack of exercise[edit | edit source]
Resting without any exercise can cause stress in horses.
Isolation[edit | edit source]
Horses are herd animals. Herds help to provide security, status, entertainment and emotional support. Horses' physical and behavioural needs are best met when they live in groups, but a number of horses still have limited / no physical contact with other horses.
NB companion animals do not have to be horses - they could be housed with other animals such as donkeys, goats and llamas.
Boredom[edit | edit source]
Boredom can cause stress in horses. Providing toys can help to address common stress-related behaviours such as cribbing and weaving. The use of mirrors can be beneficial for horses confined in their stalls. Moreover, when travelling, it has been found that the use of a mirror is preferable to travelling alone, but a live companion is still recommended when possible.
Lack of Confidence[edit | edit source]
A confident horse is better able to cope with stress. New sights, sounds and smells should be gradually introduced.
Contagious Stress[edit | edit source]
It is beneficial to speak to your horse in calming tones and to ensure that you remain relaxed, particularly if your horse becomes stressed.
References[edit | edit source]
- Goodwin D. Horse behaviour: evolution, domestication and feralisation. In: Waran N editor. The Welfare of Horses. Animal Welfare, vol 1. Springer: Dordrecht. 2007. p1-18.
- Van der Walt A. Ethology for Physiotherapists - Patient Communication and Safety Course. Physioplus, 2021.
- Iowa State University - Extension and Outreach. The body condition score [Internet]. Available from: https://www.extension.iastate.edu/equine/body-condition-score [cited 12 April 2021].
- Carroll CL, Huntington PJ. Body condition scoring and weight estimation of horses. Equine Vet J. 1988;20(1):41-5.
- University of Minnesota Equine Extension Program. Horse Body Condition Scoring. Available from: https://www.youtube.com/watch?v=KoLRjMHHnBs [last accessed 13/4/2021]
- Hy Gain Feeds. The Equine Digestive System. Available from: https://www.youtube.com/watch?v=tuzTJ77IQAY [last accessed 13/4/2021]
- Williams CA. The basics of equine nutrition [Internet]. Rutgers New Jersey Agricultural Experiment Station. 2004 [cited 13 April 2021]. Available from: https://esc.rutgers.edu/fact_sheet/the-basics-of-equine-nutrition/
- Fabian EE. Horse stable flooring materials and drainage [Internet]. PennState Extension. 2016 [cited 13 April 2021]. Available from: https://extension.psu.edu/horse-stable-flooring-materials-and-drainage
- Werhahn H, Hessel EF, Schulze H, Van den Weghe HFA. Temporary turnout for free exercise in groups: effects on the behaviour of competition horses housed in single stalls. Journal of Equine Veterinary Science. 2011;31(7):417-25.
- Chaya L, Cowan E, McGuire B. A note on the relationship between time spent in turnout and behaviour during turnout in horses (Equus caballus). Applied Animal Behaviour Science. 2006;98(1-2):155-60.
- Kumar B, Manuja A, Aich P. Stress and its impact on farm animals. Front Biosci (Elite Ed). 2012;4:1759-67.
- Padalino B, Raidal SL. Effects of Transport Conditions on Behavioural and Physiological Responses of Horses. Animals (Basel). 2020;10(1):160.
- Carson DM, Ricketts SW. Diarrhea in Horses [Internet]. VCA Hospitals. 2010 [cited 13 April 2021]. Available from: https://vcahospitals.com/know-your-pet/diarrhea-in-horses
- Górecka-Bruzda A, Jaworski Z, Jaworska J, Siemieniuch M. Welfare of Free-Roaming Horses: 70 Years of Experience with Konik Polski Breeding in Poland. Animals (Basel). 2020;10(6):1094.
- Thunes C. Ideal feed frequency for horses [Internet]. The Horse. 2019 [cited 13 April 2021]. Available from: https://thehorse.com/182673/ideal-feed-frequency-for-horses/
- Kang OD, Lee WS. Changes in Salivary Cortisol Concentration in Horses during Different Types of Exercise. Asian-Australas J Anim Sci. 2016;29(5):747-52.
- Hartmann E, Søndergaard E, Keeling LJ. Keeping horses in groups: A review. Applied Animal Behaviour Science. 2012;136(2-4):77-87.
- Lesimple C, Gautier E, Benhajali H, Rochais C, Lunel C, Bensaïd S. Stall architecture influences horses’ behaviour and the prevalence and type of stereotypes. Applied Animal Behaviour Science. 2019;219(4):104833.
- Kay R. Hall C. The use of a mirror reduces isolation stress in horses being transported by trailer. Applied Animal Behaviour Science. 2009;116(2-4):237-43.