Wild Horses vs. Domestic Management: Behavior, Diet & Health

How do the behavior and lifestyle of wild horses differ from domestic horses, and what lessons can we learn for how horses are managed?

Horses evolved as a social prey species who were able to survive in a variety of environments due to their adaptability and ability to roam long distances in search of food and water. ^[1] The adaptable nature of wild horses allowed for their domestication and introduction into human society as a work animal. ^[1]

However, the process of domestication introduced new challenges to the horse, including restricted movement, changes in diet, and reduced social interaction. ^[1] Although many horses appear to thrive in their domestic environments, there is evidence that the horse’s innate behaviors have changed very little over 6000+ years of domestication. ^[1]

Some of the changes introduced with domestication conflict with the wild horse’s natural lifestyle and can result in abnormal behaviors and increased health problems. To better understand our equine partners and how we can improve their mental and physical health, it is important for us to understand their evolutionary history as a species.

Wild, Feral and Domestic Horses

Horses are an ancient species that evolved more than 65 million years ago. ^[1] Early equines first appeared as a fox-sized, four-toed animal called Hyracotherium. This species lived in swampy regions in North America, grazing on primitive grasses. ^[1]

As this species entered new environments, they adapted to ensure survival. These adaptations led to increased speed, increased ability to access nutrients from long-stem forages, and herd behaviors. ^[1] Eventually, this led to evolution of the modern equid, Equus.

Domestication of Equus first began in Ukraine, Egypt, and western Asia more than 6000 years ago. ^[1] Humans used horses as pack animals, ridden transportation, and to pull sledges and wheeled vehicles. ^[1]

Horses who escape captivity readily re-establish similar ecological behaviors to their wild counterparts, suggesting that horse behavior is largely unchanged from domestication. ^[1] These horses are feral or free-ranging horses and can successfully adapt to a variety of environments worldwide. ^[1]

Today, the only remaining wild species of Equus is the Przewalski (Equus ferus przewalski). ^[1] Once extinct in the wild, conservation efforts have reintroduced Przewalski horses into areas of China and Mongolia. ^[2]

Time Budgets

Horses spend their lives engaging in four major behaviors: ^[3]

• Lying down
• Standing
• Eating
• Socializing

Studies show that domestic horses use their time budget (how they allocate time to each behavior) differently than wild horses. ^[3] These changes can impact the domestic horse’s mental and physical health, as they are no longer performing the activities they evolved to do. ^[3]

The following chart shows the approximate time budget for: ^[3]

• Group 1: Wild horses
• Group 2: Domestic horses housed in groups
• Group 3: Domestic horses stabled where they can see and touch other horses
• Group 4: Domestic horses stabled without contact between horses

Horses in Group 2 and in Group 3 also had free-choice hay, while horses in Group 4 had restricted hay.  ^[3]

This graph was modified from Keeling, L. J. and Gonyou, H. W., Eds., Social Behaviour in Farm Animals. CABI Publ, New York. 2001^[3]

Notable features of this comparison include:

• Horses with free choice hay and wild horses spend the majority of their time eating
• Stabled horses spend more time standing or lying down compared to group housed or wild horses
• Group-housed horses exhibit similar time budgets to wild horses

Movement

Horses evolved to have a wide home range, which ensures the herd has adequate resources for survival. In domestic life, horses often live in paddocks, pens, or pastures which are significantly smaller than the range of their wild relatives.

Wild and Feral Horses

The home range size of wild and feral horses varies depending on the availability of resources. ^[4] Home range sizes for Przewalski horses ranges from as small as 0.75 km² (185 acres) to a massive 1,356 km² (335,075 acres). ^[4] For feral horses, ranges vary depending on the type of environment, but can be up to 303 km² (74,873 acres). ^[4]

A feral horse is a free-roaming horse that comes from domesticated stock. Mustangs are an example of feral horses.

A wild horse is a free-roaming horse that doesn’t come from a domesticated stock. Przewalski horses are recognized as the last true “wild” horses on Earth.

Water is a primary driving factor that encourages horses to move around within their home range. ^[4] In areas with scarce water sources, horses may spend significant time moving between resources to ensure their needs are met. ^[5]

Horses can cover up to 32 km (20 miles) in an hour comfortably. ^[6] During the winter, eating snow may allow wild and feral horses to expand their range further from major water sources. ^[4]

Domestic Horses

Domestic horses are often unable to move around freely over large areas due to confinement in stalls, paddocks, or small pens. ^[1] One study showed that horses kept in small pens or paddocks only travelled 1.1 km/day, compared to pastured horses travelling 7.2 km/day. ^[7]

This forced immobility may increase the risk of physical health issues, including muscle disorders, lameness, and poor hoof quality. ^[1] Physical benefits of increased turnout include: ^{[1][8][9][10]}

• Increased bone mineral content
• Reduced risk of soft tissue injuries, such as tendon or ligament injury
• Maintaining muscle fitness
• Improved blood circulation in the hoof

Decreased movement associated with stabling can also reduce intestinal motility, potentially increasing the risk of colic. ^[11]

Reduced activity also affects domestic horses’ mental health. One study showed a significant decrease in stereotypic behaviors after turning out horses in a paddock for just 30-60 minutes. ^[12] Horses also had increased levels of oxytocin in their bloodstream, a hormone known to promote positive feelings and counteract depression in humans. ^[12]

Improving Domestic Life

Large pastures and 24/7 turnout are often difficult for owners to provide, particularly as modernization increasingly converts agricultural land into industrial or residential areas.

Suggestions to improve horse welfare in a domestic environment include: ^[12][13]

• Maximizing turnout time and pasture size as much as possible
• If stabled, ensuring that horses have enough room to lay down with their legs, head, and neck extended
• Providing a minimum of 2 hours of large area turnout or exercise at least 5 days per week
• Including at least 60 minutes of “free movement” (e.g., turnout, loose in an arena) per day

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Diet

Horses evolved eating a forage-based diet, primarily surviving on grasses, shrubs, and forbs in their natural environment. ^[4]

Domestic horses often have high-grain diets consisting of commercial feeds with reduced access to long-stem forages. ^[1] These changes increase the risk of gastrointestinal disease in domestic equines.

Wild and Feral Horses

The diet of wild and feral horses is 80-90% grass species, with smaller contributions by forbs (flowering plants) and browsing on other plant species. ^[4] These grasses are typically low in nutrients, requiring horses to consume a large amount of forage to meet their energy needs. ^[13]

Due to their high-forage diet, the digestive system of horses has adapted to continuous grazing throughout the day. ^[13] Feral and wild horses eat for up to 16 hours per day, making it the largest component of their time budget. ^[1]

Features of the equine digestive tract that reflect their need for constant forage include: ^[11]

• Continuous secretion of stomach acid
• Continuous activation of gastrointestinal motility
• No gallbladder to allow for bile storage between meals

Domestic Horses

Domestic horses tend to eat high-grain diets in 2-3 meals per day, with restricted forage access between meals. ^[1] Without constant access to long-stem forage, the gastrointestinal system of the horse can be compromised. ^[1]

One of the most common outcomes of low-forage diets is gastric ulcers. ^[1] A portion of the horse’s stomach, the non-glandular region, has minimal protection against the caustic effects of stomach acid. ^[1] This makes them susceptible to developing gastric ulcers.

Up to 90% of performance horses have gastric ulcers, with the highest risk in horses that are meal fed or do not have continuous forage access. ^[11]

With constant access to a forage-based diet, the forage stems form a protective mat that prevents stomach acid from splashing onto the non-glandular portion of the stomach and causing ulcers. ^[1] Saliva produced during the extra chewing necessary for digesting forage stems also helps buffer stomach acid and protect the stomach. ^[11]

Horses fed low-forage diets may also consume bedding to alleviate boredom and their need for constant feed intake. ^[14] These feeds are difficult for the digestive system to process and may lead to complications such as impaction colic. ^[14]

Inappropriate diets also contribute to behavioral problems in horses, including stereotypies. The most common stereotypies associated with low-forage diets are: ^[3][13]

• Cribbing
• Wood chewing
• Wind-sucking

Studies show that increasing forage availability reduces the frequency of these behaviors in stabled horses. ^[15]

Improving Domestic Life

The simplest change to improve the lives of domestic horses is giving free-choice access to long-stem forages. ^[13] This provides their digestive tract with a constant source of feed, which meets the horse’s evolutionary needs.

However, careful evaluation of the diet is necessary to ensure that the horse does not gain excess weight. ^[13] Strategies to increase accessibility of long-stem forages while preventing weight gain include: ^[13][14]

• Using slow-feed hay nets, hay balls, or similar toys to slow consumption time
• Placing multiple feeding stations around the paddock or pasture to encourage movement and foraging behavior
• Adding low-nutrient forages, such as chopped straw or low-quality hay, to the forage portion of the diet
• Delivering small meals of hay frequently throughout the day, so the horse does not go more than 4 hours without feed

Social Behaviors

Horses are a highly social species, as the herd lifestyle reduces the risk of predation and promotes overall safety of each individual animal. ^[1]

Wild and Feral Horses

Wild and feral horses readily form large groups with a distinct social order. ^[1] Within the group, there is a hierarchy with the most dominant horse at the top. ^[1] Below the dominant horse, there are frequently “circular” dominance systems. ^[1]

For example, horse A may be dominant to horse B, who is dominant to horse C, but horse C is dominant to horse A. ^[1] Horses also display tolerance of some individuals, where they accept a specific horse in their space without showing signs of irritation or aggression. ^[3]

These social orders are very stable within a “closed” (unchanging) herd population. ^[1] Overt aggression is rare in feral and wild horse herds once the social hierarchy is established. ^[1] Typically, changing social hierarchies are only present in young horses within a group. ^[1]

To minimize conflict within the herd, horses adopt an avoidance strategy, which puts physical distance between themselves and the horses they are submissive to. ^[1] Within the wide-open spaces that wild and feral herds occupy, this strategy works well as there is minimal competition for resources such as feed or water. ^[1]

Domestic Horses

Domestic horses often live alone (e.g., when stabled) or in small groups of 2-5 horses. Both of these scenarios conflict with their natural lifestyle and can result in behavioral problems. ^[1]

Living Alone

Keeping a horse alone conflicts with its survival instincts, as a lone horse is more vulnerable to predation. ^[3] Even if predation is not a true risk in real life, it remains an perceived risk on an instinctual level.

Isolated horses frequently develop behavioral problems, including: ^[3]

• Self-mutilation
• Pacing or box walking
• Weaving
• Pawing
• Windsucking
• Cribbing
• Isolation-induced aggression

These problems likely arise from boredom, frustration, and the stress of being vulnerable to predation. ^[3] Many of these behaviors can become stereotypic, even after removing the inciting trigger. ^[3]

Living in Small Groups

Studies show that domestic horses have a higher frequency of aggressive interactions within social groups than wild and feral horses. ^[1] There are several possible reasons for increased aggression: ^[1]

• Competition for resources such as feed or water
• Reduced space to maneuver, making avoidance strategies impossible
• Constantly changing social groups

These factors lead to increased displays of aggression by dominant horses, which may result in their owners removing them from a herd scenario altogether. ^[1]

Many horses living in small groups in domestic systems are also stabled overnight or for part of the day. ^[3] It seems likely that horses re-establish herd dynamics each time they are turned out together, increasing the potential for aggressive behaviors. ^[3]

Ideal Management for Domestic Horses

The ideal scenario for a domestic horse is a large, mixed sex, closed herd with abundant room to display avoidance behaviors and free access to feed and water. ^[1][13] Horses should live in these types of environments from birth, so they learn social cues and their place within the herd structure. ^[1][3]

However, this scenario is not feasible for many horse owners. Changes that can improve the horse’s social welfare include: ^[1][3]

• Pasturing in small groups who show tolerance towards each other
• Increasing access points for feed and water to reduce conflict
• Keeping the small groups the same for long periods of time
• Ensuring that stabled horses can see, and preferably interact with, other horses
• Minimizing time in a stall or isolated pen or paddock
• Using mirrors in stalls to simulate a companion horse

Summary

The evolutionary history of wild horses can help horse owners improve the welfare of their domesticated equine companions.

• Horses evolved to travel long distances, continuously graze on long-stem forages, and live in large social groups.
• Modern day horse-keeping practices are often at odds with their evolutionary history.
• Making husbandry changes to encourage more natural behaviors can improve the horse’s mental and physical wellbeing.
• Increasing turnout time, turnout with compatible horses, and increasing access to long-stem forages can all improve the horse’s welfare within a domesticated environment.