Fibula: One of the two bones of the leg (i.e., the lower thigh, second thigh, or lower leg).

Fiddle Front: Forelegs out at elbows, pasterns close, and feet turned out. French front.

Field Trial: A competition for certain hound or sporting breeds in which dogs are judged on ability and style in tracking, finding, coursing, or retrieving game.

Filled-Up Face: Smooth facial contours, free of excessive muscular development.

Fillers: Meant to increase volume, chemicals and other indigestible material that are added to pet food.

Fixed: (1) See Neuter. (2) Surgical procedure that permanently changes the carriage of the tail or ears.

Flag: A long tail carried high. Feathering on the tail.

Flank: The side of the body between the last rib and the hip.

Flare: A blaze that widens as it approaches the topskull.

Flat-Sided: Ribs insufficiently rounded as they approach the sternum or breastbone.

Flews: Upper lip pendulous, particularly at their inner corners.