Size

American Cocker Spaniels have an ideal size of 15 inches (38 cm) at the withers for male dogs and 14 inches for females. The breed standard states that size over 15.5 inches for males and 14.5 inches for females is a disqualification at a breed show, in order to discourage the breeding of oversize dogs.

Head

The head of an American Cocker Spaniel makes the breed immediately recognizable, with the rounded dome of the skull, well-pronounced stop, and square lip. The drop ears are long, low set, with long silky fur, and the eyes are dark, large, and rounded.

Coat

A Tri-colored and an ASCOB American cocker spaniel.

A red merle american cocker spaniel.

The American Cocker Spaniel is usually kept as a companion dog, since "very few are used for hunting any more." As pets and showdogs, the breed's coat and the colors of the coat have taken on great importance, as they are very beautiful if well groomed and cared for The coat should never be curly or have a cottony texture, but should be silky and flat, short on the head and medium length on the body, with an undercoat. Colors are divided in to categories:

• Buff (Most common color, looks like a very light tan usually.)
• Black, including
  • Solid black
  • Black with tan points
  
  
• Chocolate
• ASCOB (Any Solid Color Other than Black), defined as any color with or without tan points, and only a very small amount of white
• Tricolor, including
  • black and white with tan points
  • black and white
  • brown and white
  • brown and white with tan points (brown tri)
  • red and white.
  
  
• Parti-color and other colors
  • Roan (individual colored hairs mingled in with white hairs), with or without tan points
    • blue roan or black
    • orange roan or red
    • liver or chocolate roan, shades of brown
    
    
  • Sable (no longer recognized by the American Spaniel Club, meaning that breeding dogs of this color is discouraged.)
  • Merle (see below for more information.)
  
  
• Merle, including
  • Blue Merle (Also known as a black merle)
  • Blue Merle Parti
  • Blue/Black, Chocolate/Brown Merle Parti with tan points
  • Chocolate/Brown Merle Parti
  • Buff/Red Merle
  • Brown Merle (Also known as chocolate merle)
  
  

The merle gene is actually a gene that controls color. A merle dog (M) bred to a dog of any other color (X) will result in a dog of color X with dappled, lightened patches of the coat and possible blue eyes. A merle bred to another merle, however, will usually produce white, possibly deaf and blind puppies. A merle cocker spaniel can be registered but not shown. Merle is sometimes referred to as a "deadly gene", in that it causes various ailments; this is only true when breeding two merles together.
The location and size of tan points for black and ASCOB dogs is described in detail in the Standard.
See the article dog terminology for an explanation of terms.