Australian Shepherd Breed Standard

According to the Canadian Kennel Club (CKC) standard, the Aussie is:

• a medium size dog
  • Males: 20-23" at the withers
  • Females: 18-21" at the withers
• square and compact with exceptional agility and effortless movement
• strong, attentive, animated, and authoritative
  
• straight or slightly wavy coat of moderate length and coarseness, undercoat
  
• allowable colours; blue merle, red merle, black, or red, with or without white or tan markings
• clean cut, dry head with ears folding forward
  
• chest is deep and stomach is moderately tucked up
• tail may be docked or natural full length or bob
• dew claws may be removed

To view the complete breed standard, please follow the below links:
CKC Breed Standard
AKC Breed Standard
ASCA Breed Standard