Understanding crossbreed generations

By Dr. Mikel Delgado, PhD

Crossbreeds are the result of the mating of two purebred dogs of different breeds. 

Certain terminology is used to describe the different generations of crossbreeds. All hybrid generations are labeled with the letter F, to indicate that they are “Filial hybrids.”

The number following the letter F indicates the generation: 

• F1 is the first generation of parents of two purebred dogs of different breeds. 
• F2 is breeding two F1s together (e.g., a goldendoodle with another goldendoodle), meaning they are “second generation (two generations from the original parent breeds).”
• Genetically, F1s and F2s are the same (50% of each parent breed)

If the letter B follows the generation number, it means the dogs are backcrossed. Backcrossing is when a hybrid dog is bred with a purebred dog who is one of the breeds of origin. 

• An F1B Goldendoodle means an F1 Goldendoodle was bred with either a Poodle (most common) or a Golden Retriever.
• An F2B is either breeding an F1 with an F1B, or an F2 with one of the original parent breeds (purebred)

Backcrosses are genetically more like one of the parent breeds than the other, which some buyers may prefer.

Breeding can go beyond F2 (such as F2xF2 breedings), but these breedings are less common, and are usually just labeled “multigenerational.”