1. similar appearances
   common behaviors
2. a standard set of both physical and behavioral traits

For each breed recognized by groups such as the American Kennel Club, there exists some type of breed standard. This standard is a full description of what the ideal specimen of this breed should look like and how it should act.

1. inbreeding
   artificial selection
2. cross-breeding

With artificial selection, people select the traits they want to continue instead of "survival of the fittest." Traits favored by people may or may not be directly beneficial to the animal.

1. golden retrievers
   Chihuahuas
2. German shepherds

Guide dogs are typically golden retrievers, Labrador retrievers and German shepherds.

1. praise
   petting
2. edible treats

In order to be an effective guide dog, the animal cannot be trained to expect food in return for good behavior.

1. collie
   fox terrier
2. poodle

The fox terrier (wire) has won Best in Show a whopping 13 times.

1. It means the dogs are genetically similar because they share the same parentage.
   It means the dogs are close in nature and share a strong bond.
2. It means the dogs are bred in close quarters.

Close breeding means that purebred dogs are uniform in appearance. It's difficult to escape genetic problems because so many of the dogs in that closed population share the same ancestry.

1. They aren't pure breeds.
   The poodle genes are stronger than the Labrador genes.
2. Designer dog mixes cannot reproduce.

You can't breed one Labradoodle with another Labradoodle and get Labradoodle offspring, because they aren't a part of a pure breed. Genetically, you're instead breeding a heterozygote to another heterozygote.

1. 350
   500
2. 750

Today, there are more than 350 recognized breeds, an infinite number of mixes and dogs that are no breed at all.

1. golden retriever
   Labrador retriever
2. beagle

The Labrador retriever was the most popular breed in 1997, 2002, 2006 and 2007.

1. Labrador retriever
   hound
2. German shepherd

German shepherds are the most common type of police dog because of their intelligence, strength, aggression and sense of smell.