Final answer:
Dogs are generally considered puppies until they reach about one year of age, but this can vary depending on breed size, with larger breeds taking longer to mature. The early months are critical for development and training, with factors like socialization affecting their future roles. All dogs share reproductive traits despite their phenotypic differences.
Step-by-step explanation:
Dogs, scientifically known as Canis lupus familiaris, are typically considered puppies until they reach one year of age. However, this can vary with the size and breed of the dog. Smaller breeds may be considered adults at around 9 to 12 months, while larger breeds may still be seen as puppies until they are around two years old. In general, dogs grow rapidly within the first few months of their lives, and this period is crucial for training and socialization as evidenced by the structures of training programs for young dogs. After three months of training, young dogs can be categorized based on traits relevant to their suitability as service dogs, such as sociability or activity level.
Despite phenotypic differences such as size, build, and coat, domestic dogs share common biological traits that allow them to sexually reproduce. All dogs have a period in which they are considered immature or 'puppies' before they reach reproductive capability and full physical growth. This stage includes rapid development, where experiences and learning can significantly shape their future behavior and abilities as adult dogs. Selective breeding over time has resulted in interbreeding capabilities among varied dog breeds, producing a wide spectrum of appearances but maintaining general developmental stages from puppyhood through adulthood.