Horses

1
Horses

• Anatomy and Physiology

2
Anatomy and Physiology

• Integumentary
• Skin and hair
• Shiny hair is associated with good health
• Skin important in thermoregulation
• Very sensitive with many nerve endings
• Large sweat glands
• Hair growth controlled by photoperiod

3
Anatomy and Physiology

• Coat colors
• Skin and hair color result from pigmented melanin
  granules
• Variation is controlled genetically
• Highly complex with many colors and combinations
• Two most basic
• Black
• Red (chestnut)

4
Anatomy and Physiology

• Color and genetics
• Dominant white gene thought to be lethal is
  homozygous
• Heterozygous white results in pure white horse
  with pink skin and colored eyes
• Graying gene is dominant
• Gray horses born any color, gradually turn to
  white

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Common Markings
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Anatomy and Physiology

• Musculoskeletal system
• Conformation determined by skeletal frame and
  muscles
• Wild horses need strong bones and muscles
• Most of body weight supported by backbone
• Head used to maintain balance

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Anatomy and Physiology

• Ligaments and tendons
• Foot
• Laminae
• Keratin
• Hoof wall
• Frog
• Wedge-shaped mass
• Shock absorber
• Minimizes slipping

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Anatomy and Physiology

• Musculoskeletal system
• Gaits
• The way a horse walks or runs
• Four natural gaits
• Walk
• Trot
• Canter
• Gallop

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Anatomy and Physiology

• Gaits
• Walk
• Slowest gait
• Four-beat gait
• 1-2-3-4
• Trot
• Two-beat gait
• 1-2-1-2
• Speed can vary
• English riders often post

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Anatomy and Physiology

• Gaits
• Canter
• Three-beat gait
• 10 to 15 mph
• Lope
• Slow canter
• Galloping
• More rapid, extended canter
• Can exceed 40 mph
• Short periods of time

https//www.youtube.com/watch?vDYxWGvWb-0I
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Anatomy and Physiology

• Teeth (36-40)
• Six incisors to bite off forage
• Molars grind to break down foods
• Male horses have small canine teeth with no known
  function
• Wolf teeth
• Extra set of small premolars in front of larger
  premolars
• Foals born without teeth
• Eruption and wear of incisors used to estimate
  age of horses

12
Anatomy and Physiology

• Respiratory system
• Rate at rest is 8 to 16 breaths per minute
• Several factors increase rate
• Exercise
• Heat
• Humidity
• Fever
• Anxiety

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Anatomy and Physiology

• Cardiovascular system
• Heart and blood vessels
• Heart rate of adult horse at rest is 35 to 40
  beats per minute
• May exceed 200 bpm during strenuous exercise
• Average heart-weight to body-ratio for horses is
  0.94
• Heart of average Thoroughbred is between 8.5 and
  9 lb
• (human .5lbs)

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Anatomy and Physiology

• Digestive system (gastrointestinal tract)
• Non-ruminant herbivores
• How has domestication changed the way horses eat
  today?
• Normally graze eat small meals throughout the
  day
• Most domesticated horses get large meals twice a
  day and have their stomach sit empty for long
  periods of time, where acidic conditions can
  cause stomach ulcers

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Anatomy and Physiology

• Bacterial fermentation of cellulose mostly done
  in large intestine
• Susceptible to toxins and mold in feed colic
• Horses typically defecate 6 to 10 times a day

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Anatomy and Physiology

• Reproductive system
• Long gestation period
• 340 days (11 months)
• Bred to foal during the spring
• Seasonally polyestrous
• Photosensitive
• Optimal time for breeding is in late estrus
• Artificial insemination becoming more popular

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Anatomy and Physiology

• Labor is short
• 10 to 15 minute delivery time
• Newborn foal will stand and start searching for
  food
• Imperative foal obtains colostrum
• Antibodies do NOT cross placenta in horses
• Foals that are weak or unable to suckle should be
  fed colostrum using a bottle or stomach tube

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Anatomy and Physiology

• Special senses
• Vision
• Wide field of vision
• Monocular

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Anatomy and Physiology

• Audition
• Can detect sounds at frequencies well above those
  heard by people
• Hearing Range 55-33.500Hz
• Do horses communicate with their ears?
• Olfaction
• Bonding of mare and foal dependent upon smell
• "flehman reaction
• WHY?

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Anatomy and Physiology

• Taste
• Horses like salty and sweet foods
• Do not bitter or sour foods
• Refuse to drink foul water
• 25,000 taste buds (humans 8-10,000)
• Touch
• Very sensitive
• Best to announce presence to a horse prior to
  reaching out and touching it