Behaviour of the horse ( caballus)

Boglárka Köböl Eszter Losonczi Viktor Jurkovich Origins Evolution of horses (?)

Eohippus Modern horse

● 55-60 million years ● 2 million years

● fox-sized, 4 toes ● walking on 1 toe (the 3rd) ● teeth: eating leaves ● eating grass ● living in forest 2 ● living in grasslands Origins The geographic isolation in the late Pleistocene → development of distinct specieses

● Przewalski horse, true horses, asses (donkey, onager etc.),

Onager

Przewalski horse Asian wild donkey 3 Origins Crosses • horses x other equid species → possible but hybrids are normally sterile, except for the Przewalski (66 chr.) (horse 64 chr., 44 chr., donkey 62 chr.) Ancestor of the true horse (Equus caballus) is considered to be the wild horse (Equus ferus, last known representative was the tarpan - extinct) Some sources claim that horses are linked to the Przewalski horse True horses occupied Eurasian areas north of the great mountain ranges Wild horses did not exist in America, Africa, south Asia and Australia. Different environmental conditions → two main types within the species (today: 'cold-blooded' and 'hot-blooded') 4 Domestication

Archaeological findings indicate that horses were originally hunted (and maybe husbanded) as a food animal One of the last to be domesticated from around 3-4000 BC in the Eurasian steppes (rich sources in Ukraine and Kazakhstan)

Dating of domestication is disputed By 2000 BC there was a sharp increase in the number of horse bones found in human settlements in northwestern Europe, indicating the spread of domesticated horses throughout the continent. 5 Changing roles Later used for draught and riding (warfare) Spreading domesticated herds were supplemented with local wild horses During the mutual history of humans and horse, the horse has had a very high-ranking status, an aristocrat of livestock, irrespective of culture, age and people.

6 Current status

Since the 1950's horses have played an increasing role in sports and recreation. Their role from farm animals have shifted to companion animals. The housing and management has not undergone a dramatic change in its history. Being kept isolated from conspecifics, humans are an important part of the horse's social environment.

7 Vision

Prey animal →good vision, panoramic field of 330-350°. Blind spots • behind itself when the head is held alertly forward • just in front of the muzzle. Limited ability to focus between distant and close objects – the lens can hardly accomodate.

Acclimatisation is slower than that in humans (going out from stall!). When focusing on objects to the fore, horses may momentarily lose the ability to observe from the rear and to the sides. 8 Vision

9 Vision

Extremely sensitive to movement in all areas of their visual field. • Good ability to consider tiny changes in body movements (e.g. ear position). • ~ human peripheral vision Horses see well even in dusk (tapetum lucidum)

10 Blind area is influenced by the position of the head

Normal position Over-bent

11 Blind area is influenced by the position of the head

12 Colour vision

Horses have relatively little need for colour vision. Both cones and rods are present in the retina, but rods dominate The high proportion of rods to cones → excellent night vision (but insufficient to make horses innately fearless in areas that are poorly lit) Horses are dichromats, they struggle to discriminate between green and grays of similar brightness. • Individual variations (some can see red but not yellow, some can see yellow and not red).

13 Colour vision trichromats (human) dichromatic vision

14 Differences between human and horse visual field

Human

Horse

15 Differences between human and horse visual field

Human view

Horse's left eye The human view is of the city itself and not much more, since our vision is so frontal. The horse, by contrast, sees the city and everything else simultaneously right back to the man taking the photograph. 16 Differences between human and horse visual field

17 Hearing of hearing is very well developed. Ears • funnel shaped • can move in unison or independently of each other • 10 muscles → the ears can be moved around a lateral arc of 180° → location of the source of the sound within an arc of ~ 25° (poorer compared to humans, 1°). Hearing • well equipped to hear faint noises (from up to 4.5 km). • Broad hearing range (55 Hz – 33.5 kHz, most sensitive 1-16 kHz). • There is some suggestion that horses can respond (with nervousness and vocalization) to sounds of very low frequencies, such as geographical vibrations preceding earthquakes. It is thought

that they do not ‘hear’ as such, but can detect the vibrations through18 the hoof. Hearing

The direction in which the ears point ~ direction a horse’s attention is focused.

This seems particularly useful when horses, as group animals, may have their vision obscured by the bodies of their companions.

19 Smell

Smell and are linked neurologically, as they are in many other species. Horses familiarize themselves with foreign objects by smelling them. Sniffing: part of greeting rituals between horses. Forced exhalations: helps deep inhalations that allow the horse to sample odor molecules. Rarely do humans allow sufficient time for horses to gather this sort of information. At the same time, we should remember that because of the combined effect of bathing, using soaps, changing clothes and manipulating all sorts of materials with our hands, our odors are likely to change over time in a way that thwarts their reliability for horses. 20 Flehmen response

In addition to the conventional olfactory system, the horse contains an accessory olfactory system in the form of the . In contrast to many other species, the VNO of horses does not open into the oral cavity. It is used to detect (from horses and other species) in urine and other moderately volatile odors.

21 Flehmen response

Horses are unique in that they can flehmen in response to volatile substances borne in the air ( → direct contact of the lips or tongue with urine) Frequency of flehmen response • colts > fillies • foals > their mothers Role • development of sexual surveillance • processing. • courtship.

22 Taste Salt, sour, sweet and bitter • pivotal in the early bonding of a mare with her foal, • when two horses groom one another • determinate caloric content of foods • discriminate among different foods • exercise preferences • avoid a food associated with illness • provide nutritional information about food (select salty foods in case of diet deficient in salt)

23 Touch

Variable over different areas of the horse’s body. • very sensitive areas: withers, mouth, flank and elbow regions • some horses dislike their ears, eyes, groin and bulbs of the heels being touched As herd animals it is important that they are sensitive to the presence of others at their sides → move as a cohesive social group in times of danger and to initiate bouts of mutual grooming. When riders use their legs to move horses beneath them they are capitalizing on this

innate sensitivity. 24 Touch

Mutual grooming map

25 Vibrissae around the eyes and muzzle

• rich afferent nerve supply • inform the horse of its distance from a given surface • detect vibrational energy (sound) • in the neonatal foal → facilitate location of the teat • together with the lips, they gather tactile information during grazing and head-rubbing Vibrissae around the eyes and muzzle Horses subjected to road transport subsequent to whisker trimming → inability to detect fixed objects → contributory factor to facial trauma Because vibrissae can be identified as anatomically different from normal hair coat, the trimming of whiskers has been outlawed in some country (e.g. Germany)

27 Touch

Sensitivity of the skin varies • thickness of coat • thickness of skin • receptor density Skin nociceptors become less responsive if the stimulus is repeated The buccal mucosa is as sensitive as the skin to tactile stimuli. • discriminative ability → empty their mouths if fine inedible material taken in during grazing → rarity of intestinal foreign bodies (compared with ) We have exploited this sensitivity by using oral discomfort to control horses. We should respect this sensitivity and avoid the heavy-handed rein-pulling that ultimately destroys it. 28 Eating

The average horse dietary botanical composition for all seasons consist of 69% grass, 15% forb (herbs), 16% shrub.

● Within legumes, horses are reported to prefer alfalfa pasture.

● Preference for young growth and select leaf material rather than stems. Horses eat in total for 12-17 h or more, both during daytime and at night

● when kept indoors, they must have some forage for the night.

● When forage is scarce the grazing period may exceed to 19 hours and horses increase their bite-frequency.

● Peaks in foraging occur in the early morning and late afternoon with bouts lasting from 30 min to 4 hours.

29 Time budgeting

Free range horses Stabled horses

30 Eating

A horse foraging exclusively on high fiber strubtrates may chew 57 000 times per day. Moderately intensive stabled conditions → almost halved Consequences:

● salivation decreases

● buffering effects of bicarbonate diminished

● gastric acidity rises

● risk of gastric ulceration increases

31 Eating

Horses graze by collecting grass with their prehensile upper lip and biting it off near the ground with the front teeth. When grazing, they move ahead slowly with one leg at a time.

32 Eating

Plants are distinguished on features of theis visual appearance (leaf shape and colour), as well as their odour • Selectivity is hampered at night →reduced carbohydrate intake • horses avoid areas contamined with equine feces → olfaction plays a particularly significant role Flexibility in dietary intake → adapt to the fluctuations in the availability of vegetation When availability of preferred items is limited, horses are quick to reach a compromise between plant quality and quantity to meet their dry matter requirements. 33 Drinking Submerge their lips below the water surface and generate a pressure gradient Movement to water • usually made by the entire herd • at least once per day • most commonly in the afternoon • higher-ranking members of a band drink first When food and water are freely available 90% of drinking occurs within 10 minutes before to 30 minutes after feeding Water intake • stabled horses: 2-4 litre per kg of dry matter food consumed • working horses: related to exercise; up to 90 litres/day 34 In winter, very cold water can be aversive → dehydration, colic Locomotion

Horses have been shown to travel on open ranges (for example, to water) up to 65–80 km daily. For pastured horses, movement during grazing is the main initiator of locomotion → ~ 20 km. The distance that grazing horses travel depends on • the location of water • availability of food • time that has been spent foraging

35 Locomotion

The natural gaits of a horse are: • slow and fast walk • trot • gallop • other seemingly inherent gaits occur in certain breeds, e.g. rack in Icelandic horses. • jumping (if they are thaught; untaught horses may avoid obstacles only 60 cm high rather than clear them by jumping voluntarily • swiming (they do not actively seek to swim when close to water)

36 Locomotion

Locomotion is useful as an indicator of distress, especially when conducted at the expense of feeding;

• solitary horses walk and trot three times more often than those that can make auditory, visual and physical contacts with other horses

• locomotion’s role in recreation is considerable, with 75% of the kinetic activity of foals, for example, being in the form of play.

37 The cycle of movements at the walk

The weight-bearing limbs at each stride are indicated. The normal equine walk is a four-beat gait in which the feet move individually and sequentially in diagonals as follows: right fore, left hind,left fore, right hind. Collected, medium, extended and free walks are recognized. 38 The cycle of movements at the trot

The weight-bearing limbs at each stride are indicated. The trot is a two-beat gait in which the diagonal pairs of limbs move in apparent synchrony and the footfalls of the diagonal limb pairs are evenly spaced in time. Collected, working, medium and extended trots are recognized. 39 The cycle of movements at the canter and gallop

Canter Gallop The weight-bearing limbs at each stride are indicated. The canter, with three beats to the stride, and the gallop, with four, are asymmetrical gaits and are labeled left or right in reference to the leading foreleg and ipsilateral hindleg. Collected, working, medium and extended canters are recognized. 40 Other gaits – pace and rack

Pace

Stepping pace

Rack

The weight-bearing limbs at each stride are indicated. The most lateral gait, the pace, is innate for some horses (e.g. Icelandics) but can be acquired by others. As with the trot, there are two periods of suspension in each

pace stride. Ipsilateral couplets are used almost 41 synchronously. Airs above the ground

42 Body care – self grooming

In addition to maintaining the health of the integument, grooming behaviors can contribute to the affirmation of social bonds not least by reinforcing affiliations and sharing odors. Horses groom their bodies by

● rolling on the ground,

● rubbing against their own legs or against trees, food or water troughs etc,

● nibbling or snapping on their hips, flanks or limbs. They groom eye, face, nose and nostrils by rubbing their face up and down the side of one of their forelegs.

Horses do not use their tongues to clean out their nostrils,43 as do cattle. They snort to do so. Grooming styles: • rolling • shaking • rubbing • scratching and nibbling (of both the back and forelegs).

44 Mutual grooming

Mutual grooming not only allows Mutual grooming helps horses to reach areas that defy equids to develop and self-grooming strategies, but also maintain pair bonds. facilitates the exchange of odors and has been shown to reduce heart rate when conducted in certain parts of the mane and withers. Grooming of the withers by humans has a similar calming effect. Mutual grooming can begin in the first week of life but peaks in the second and third months of life. 45 Mutual grooming

Broadly speaking, regardless of their age, females spend more time mutually grooming than males. Mutual grooming partners are usually preferred associates that are close in social rank. In a natal band, mares and their offspring mutually groom kin rather than unrelated conspecifics. The stallions in multi-stallion harems will mutually groom one another. 46 Mutual grooming

Recent reports indicate that low-ranking individuals groom more and initiate more groomings and that allogrooming may have a role in appeasement. However, most bouts are ended by the departure of the higher- ranking member of the dyad. Mutual grooming between foals is often observed before or after a bout of play. When allowed to interact freely with other horses after 9 months of social deprivation, colts stabled singly showed significantly more social grooming than colts stabled in groups, which may reflect a build-up of motivation (a post-inhibitory rebound effect). 47 Mutual grooming with humans

When they have their withers scratched, many horses will attempt to reciprocate as a form of mutual grooming. In most cases this is discouraged because people are fearful of being bitten.

Scratching by humans can act as a highly valuable primary reinforcer, so an appreciation of the pleasure that grooming may bring can help to consolidate the horse-human bond.

The need to have a clean horse has been over-stated by some horse care manuals. The perceived need to pull manes and tails undoubtedly irritates many horses and possibly compromises the horse-handler bond. 48 Rest and sleep

Horses are active for 80% of the day and 60% of the night. Rest as sleep or as total muscular relaxation is a basic need for horses, which must be met. Stabled horses are recumbent for 2 h daily in 4-5 periods.

49 Rest and sleep Drowsing Sleeping

● A drowsing horse stands with ● The two types of sleep clearly its eyelids partly opened and defined in horses are slow-wave its head hanging at a medium sleep (SWS) and rapid eye height. movement (REM) sleep.

● Muscular and skeletal ● Some muscular tone is retained mechanisms allow the horse to in SWS, even when the head is remain upright with a resting on the ground during minimum of muscular effort. sternal recumbency. It is the only form of sleep that occurs in ● The advantages of remaining standing horses. standing include the ability to achieve a quick escape if ● Although it may increase in threatened, but also avoidance horses that are unable or of the cardiorespiratory reluctant to lie down, SWS compromise that comes with cannot compensate for lost recumbency. REM. 50 A horse’s posture changes in various states of activation: (a) resting with weight distributed among only three legs; (b) lying down; (c) sternal resting positions; (d) recumbent resting attitudes; (e) arising. 51 Recommended readings

Ekesbo, I. 2011. Farm animal behaviour. Characteristics for assessment of health and welfare. CABI, Wallingford, UK, ISBN: 9781845937706 Jensen, P. 2009. The ethology of domestic animals. 2nd ed. An introductory text. CABI, Wallingford, UK, ISBN: 9781845935368 McGreevy, P. 2004. Equine behaviour. A guide for veterinarians and equine scientists. Saunders, ISBN: 0702026344

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