November 23, 2008

Animal behaviour and welfare: Horse Part 1


Origins: Domestication: Senses: Teeth problems

By Dr Clive Dalton

Horse origins
  • The ancient ancestors of the horse were small many-toed animals that then evolved one toe to became a hoof. Two million years ago the horse developed into Equus species in North America from which it spread to the old world and South America across the land bridges.
  • Then there was more general migration and diversification, They developed into a very mobile animal that uses speed, bucking and kicking to escape predators. The horse is a panic species!
  • Of the 5 main domestic animal species, the horse was the last to be domesticated. It is least affected by human manipulation and artificial selection.
  • The horse was first used by man for food, then transport, riding for military use, then for draft power and transport, and finally for recreational riding which is a major use today.
  • It was thought that Mongolian tribes were first to domesticate the horse and by 1500 BC different types of horse were evolving.
  • The problem was to find out where this happened. Research in 2009 has confirmed that the Botai culture in Kazakhstan were using horses for for transport and milking them between 3700BC and 3100BC.
  • Prezewalski horses are still found in that area as the last survivor of the early horse.

The horse still provides a range of services for humans:
  • Transport - they carry people in both war and peace.
  • Power - they pull loads and farm implements.
  • Meat - horse flesh is popular in many cultures.
  • Milk. Mares milk still supports families in some cultures.
  • Hides and skins are still valuable.
  • Hair from mains and tails is still in demand.
  • Entertainment - racing and betting.
  • Sport and competition.
  • Ceremonial uses.
  • The pleasure in ownership of a noble animal for leisure.

Horse senses

  • The horse has keen sensory perception developed from its evolution and it has one of the largest eyes of any modern animal.
  • It has a special light intensifying device which reflects light back on to the retina, giving good vision in poor light. In the wild horses are active at dawn and dusk.
  • The eye structure allows it to see the slightest movement so will panic easily by something on the periphery of its vision.
  • Having binocular vision in front of 60-70 means the horse needs to move the head to see where it is going. It can only focus fully for a short distance ahead - about 2m.
  • This is a problem in jumping - it focuses then must remember and trust its memory about the object it has seen.
  • Horses have a wide monocular (panoramic) view of the horizon and can see about 340-360 around it.
  • As the eyes are on the sides of its head, the horse does not normally see objects in depth. It sees them like we do with one eye closed. It sees them with less detail than humans but is more sensitive to movement.
  • The eyes are perfectly placed for cropping pasture, which it does this for half its life!
  • The horse's visual area is more towards the ground than the sky but it can raise its head quickly and focus on objects at various distances away.
  • Colour vision is still debated. Some work shows the horse can see colour starting from yellow, green, blue and red in that order.
  • A horse needs time to adjust vision between light and dark which is worth remembering when loading horses from bright light into dark transport vehicles.
  • The horse has a blind spot behind its head which increases when the head is lifted. So it's important to allow the horse to move its head to see objects in its way.
  • Horses are generally reluctant to enter dark enclosures but quieten down when in there and feel safe looking out into the light. Horses can often be blindfolded to quieten them.
  • Don't look a strange horse in the eye as it's a threatening pose.
  • A horse will go in the direction it is looking so point it correctly.
  • Horses have a broader range of hearing than humans and can hear up to 25,000 cycles per second (cps) and have acute hearing in the high and low frequencies.
  • Humans have noticed horses' early response to earthquake vibrations.
  • Horses have 16 muscles that control the ears which they can swivel 180 degrees.
  • When ears laid fully back this cuts their hearing severely.
  • Horses are alert at all times except in deep sleep which only occurs in very short spells.
  • Smell is well developed in the horse and this is why wild horses are difficult to stalk except upwind.
  • The horse has a Vomeronasal organ (VNO) and the Flehmen response is very obvious in stallions sniffing mares on heat.
  • Horses meet nose to nose and smell each other.
  • They are very sensitive to smells in their environment, e.g. dung, dirty troughs, musty feed, bad water and certain plants.
  • Smell is very important in feed selection.
  • Horses are attracted by sweetness and sugar so molasses, water melon rind, peaches and beer are all relished.
  • They (especially foals) reject salty, sour and bitter tastes at about the same level of acceptance as humans.
  • Touch is one of the most acutely developed senses in the horse.
  • They can sense a fly landing on any part of their body through their coat and flick it off.
  • Horses are "inter-pressure" so when you apply pressure and move into the horse you will get reverse response.
  • Horses push and barge each other in physical contact to communicate. You see this in mares and foals interacting.
  • Horses respond to touch all over the body but especially around the head so ears and eyes are especially sensitive areas. They don't like their ears pulled.
  • The upper lip and muzzle are very sensitive to tactile stimulus, and are equivalent to our fingers.
  • The whiskers that grow from the muzzle and around the eyes in the horse are like an insect's antennae. They are especially useful in low light conditions when the horse is nosing around. You should not cut them off!
  • Touch plays a major role in their social life and riders use it to signal intentions to the horse.
  • So when leading a horse - be positive.
  • Horses have a "point of balance" as described for cattle behind shoulder and in centre of head.
  • Horses have very good long-term memory which is useful for an animal that grazes over a large territory.
  • It can be seen when a horse will remember a place where it got a fright and will continually shy at that place for years afterwards.
  • But its memory can be variable and reinforcement in training is important.
  • A horse will learn nothing when under stress - as the survival urge will blank out memory.

  • Horses are strong swimmers when forced to enter deep water.
  • They swim with a dog-paddle action.
  • In training there is no problem for a fit horse to swim around a pool for 30 minutes.
Problems with teeth
  • Cheek teeth in the horse may become unevenly worn so they don't grind feed efficiently and can cause ulcers on the tongue.
  • The signs of this include dropping feed from the mouth while chewing, bulging of the cheeks caused by wads of food becoming impacted between the teeth and cheek, and/or green staining around the mouth caused by drooling of saliva.
  • Overgrown edges on cheek teeth are common in elderly ponies and horses.
  • Treatment is by rasping the sharp edges and it takes a trained person like a veterinarian or a horse dentist to do this effectively.
  • To prevent problems, it's wise to have the cheek teeth of ponies and horses rasped regularly, perhaps once a year or so by a veterinarian or horse dentist.
  • Periodontal disease can affect cheek teeth. It's caused by infections of the gum and supporting structures around the cheek-teeth roots.
  • In severe cases the bone becomes swollen and sore, then the animal is reluctant to chew its feed and it gets thin.
  • If you suspect any problems, veterinary care is needed to avoid behavioural and welfare problems.

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