EQUUS

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EQUUS

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Evolution

• Horses evolved from a small dog-like creature
  which had four toes
• Horses still have rudimentary toes extending up
  into their legs

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Evolution

• Roamed heavily forested areas
• Stood 14 inches high approx. 12 lbs.
• Predecessors of modern horses in US 58 million
  years ago.
• 4 ft tall, 4 toes on front, 3 on back
• Before extinct in America Alaska to Asia and
  Europe
• Formed European stock predecessors for todays
  horses, Zebras, others

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Predecessors of Todays Horse

• Evolved from three primitive types of horse
• Forest Horse
• Przewalskis Horse
• Desert Horse

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Early contact with Humans

• First use ever was as a food source
• 1st domestication 5,000-6,000 years ago
• Herding
• Chariots
• Sports
• War

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Horses in North America

• None here when Columbus landed fate unknown
• Reintroduced by Spain 1519, Cortez
• Source of wild horses of west Native Americans
• New England work horses
• Mules by George Washington
• Late 1800s 94 energy was animal and human
• Today 94 energy coal, oil, gas, water
• overhead

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Table 21-1, continued
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Figure 2113  
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Horse Breeds

• Over 300 Breeds in the world
• Light, Pony Breeds or Draft horses
• Light Horses 35 breeds important in USA
• racing, riding, showing, stock work, harness
• 14.2 17 hands tall 900-1400 lbs
• categorized by pedigree, gait and(or) color
• e.g. Quarter Horse, Tennessee Walker, Palomino

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Horse Breeds

• Ponies 10 breeds important in the USA
• lt 14.2 hands tall, 500-900 lbs.
• e.g. Shetland
• 3. Draft horses
• heavy work, pulling, showing
• 14.2 17.2 hands, 1400 lbs.
• e.g. Clydesdale, Percheron

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Draft Breeds

• Percheron
• France
• Mostly black or gray
• Noted for handsome, clean-cut head
• Farm work and exhibition

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Draft Breeds

• Belgian
• Belgium
• Bay chestnut and roan most common
• Lowest set most massive draft breed
• Farm work and exhibition

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Draft Breeds

• Shire
• England
• Bay brown or black with white markings
• Tallest of draft breeds
• Feathers on legs
• Farm work or exhibition

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Draft Breeds

• Clydesdale
• Scotland
• Bay and brown with white markings
• Superior style and action
• Feathers on legs

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Ponies

• Shetland
• All colors
• Known for small size
• Classic type- short and chunky
• Modern type- fine boned, long necked

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Ponies

• Welsh
• Any color
• Intermediate size

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Ponies

• Pony of the Americas
• Iowa, USA
• Similar to appaloosa in color
• Happy medium of Arabian and Quarter Horse in
  miniature

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Light Breeds

• Quarter Horse
• 1st in registrations
• All colors
• Virginia, USA (1600s)
• Short burst of speed Quarter of a mile race
  horse

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Light Breeds

• Paint
• 2nd in registrations
• Red and white or black and white
• Spanish explorers

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Light Breeds

• Thoroughbred
• 3rd in registrations
• England
• Racing

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Light Breeds

• Tennessee Walker
• 4th in registrations
• Selected for gait running walk
• Smooth, easy ride
• Pleasure and show

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Light Breeds

• Standardbred
• 5th in registrations
• Made in USA
• Harness racing
• Pacer lateral leg pairs move together
• Trotter - diagonal

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Light Breeds

• Appaloosa
• 6th in registrations
• Palouse Valley in Washington (Nez Perce)
• Spots and splashes of color, white over loin
• Gentle disposition

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Light Breeds

• Arabian
• 7th in registrations
• Arabia
• Oldest purest breed
• Dished face, arching neck, large eyes and
  nostrils
• Black skin, various body colors

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Light Breeds

• Morgan
• First US light breed
• Justin Morgan
• Strong, willing, able
• Brown, bay, black, chestnut
• Stock saddle horses

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Warm Bloods
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Color Breeds

• Palomino

• Buckskin

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Equine Coat Color Genetics

• Price differences for horses of various colors
  have created a demand for knowledge about color
  genetics
• Coat color is determined by a combination of
  several genes

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Gene W

• Unable to form pigment in skin and hair
• Overrides all other color genes
• WW lethal, dies in early pregnancy
• Ww pink skin, white hair, brown or blue eyes
  (albino)
• ww allows expression of other color genes

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Gene G

• Causes horses to be gray
• Progressive graying, any color at birth
• Original skin and eye pigment maintained
• GG becomes gray
• Gg same as GG
• gg no graying

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Gene E

• Controls black hair
• EE ability to form black skin and hair
• Ee same as EE
• ee red hair (chestnut, sorrel), black skin

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Gene A

• Controls distribution of black hair
• Affects only EE and Ee
• AA black at points (mane, tail, legs)
• Aa same as AA
• aa black over entire body

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Gene C

• Cream gene
• Causes pigment dilution
• Incomplete dominance
• CC red and black diluted to pale cream
• Cc red diluted to yellow
• cc full pigment according to other genes

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Equine Coat Color Genetics
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Bay EE/Ee, AA/Aa, cc, ww, gg
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Buckskin EE/Ee, AA/Aa, Cc, ww, gg
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Equine Coat Color Genetics

• White X White? Ww -- -- -- --
• 25 dead, 50 White, 25 any color
• Red X Red? ee, aa, cc, ww, gg
• 100 Red
• Buckskin X Buckskin? EE/Ee, AA/Aa, Cc, ww, gg
• Bay, Black, Red, Buckskin, Palomino, Cremello

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Equine Coat Color Genetics

• http//www.vgl.ucdavis.edu/7Elvmillon/coatcolor/c
  oatclr3.html

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Reproduction

• Horses are a model of reproductive inefficiency
  
• Puberty
• Estrus Detection
• Mating
• Breeding Season
• Foaling

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Puberty

• Fillies _at_ 12-15months
• breed at 2yrs
• Colts ready for breeding at 2yrs
• No known effect of subjecting fillies to stallions

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Estrus Detection

• Relaxation of external genetalia
• Frequent urination
• Watery mucous discharge
• receptiveness to stallion
• teasing

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Estrous Cycle

• Cycles are 21-23 days long
• Estrus is 3-7 days long
• Ovulation can occur anywhere from one day before
  to one day after the end of estrus
• No way of predicting the length of estrus

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Estrus Detection

• Ovulation nearing
• Palpation and ultrasound are the most valuable
  tools for detection
• Both are used to check size of follicle
• Avg 4.5cm follicle single ovulation

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Breeding

• Natural and A.I. usually done every other day
  once palpable follicle is detected or 3rd day
• Best if sperm deposited within 12 hrs of
  ovulation.

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Breeding

• Would this be a problem in the wild??
• Mate every day the mare is in estrus
• One source of created inefficiency

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Figure 2115  Mare seasonality. (Source Slusher
et al., 1998, p. 3974.1. Used with permission.)
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Breeding Season

• Cycles in mares controlled by daylength
• Breeding season lasts from Early Spring until
  Late Summer
• How long is gestation?
• 336 days
• When do mares recycle after foaling?

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Postpartum Anestrus

• Foal Heat when?
• 7-10 days after foaling
• Can they get pregnant?
• What are benefits/risks
• Benefits pregnant for next year
• Risks early embryonic mortality
• Later term abortions
• Gamble breed here or wait to later heat
• Risks of waiting?
• May move into seasonal anestrus wait till next
  year

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Artificial Lighting

• Use to extend breeding season
• Can be done with a regular 100 watt bulb
• 16 hrs
• 60-80 days prior to normal cycle

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• Slides after this point were not covered in
  lecture.

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Foaling

• Pre-foaling measures
• Watch teats for waxing
• sinking in of haunches relaxin
• safe, quiet, place to foal
• mares may become colicky

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Stage 1

• begins with the onset of contractions
• lasts 1-2 hours
• foal moving into position
• ends when the water breaks

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Stage 2

• actual expulsion of the foal
• 30 minutes or less
• normal foal presentation
• mare may stand up or lie down

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Stage 3

• afterbirth is expelled
• 1-3 hours
• over 3 hours could lead to massive infection

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Health Management

• Common disease
• equine encephalitis (aka. sleeping sickness)
• viral annual vaccination
• influenza
• viral show horse
• strangles
• bacterial highly contagious vaccinate
• equine infectious anemia (aka. swamp fever)
• no treatment Coggins test for show/sale

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West Nile Virus

• First case reported in the Western Hemisphere in
  1999
• Vector Mosquitos
• Effects mainly birds, horses and humans
• Encephalitis