How do you differentiate between a terrier and a labrador when the dog is small?

You can distinguish between the two dogs by their characteristics.

Characteristics of Labrador:

Ears: hanging, moderately close to the head, tending to tilt back and slightly below the head; just above the eyes.

Eyes: Sharp eyes show good temperament; intelligence and cleverness characterize this breed. The eyes are medium sized and positioned apart, neither protruding nor too deep.

NECK: The neck is of correct length which allows him to do his recovery work easily. It is well muscled and not proudly muscled.

PEDALS: Strong and compact with rounded toes and well developed pads. Open paws with protruding joints, or paws curved and bent outward is a serious defect.

Characteristics of the earth dog:

The traditional Chinese garden dog, also known as the earth dog, in some places in the north, also called "earth dog", belongs to the carnivorous animals, is a mammal dog, its shoulder height of about 40 ~ 60 cm, about 15 ~ 35 kilograms. Local breeds need to be preserved.

Head:The features of the head are more closely related to the appearance of the ancestral wolf, such as the tip of the nose, mouth, mouth and forehead. Ears:Ears are high, small, erect or semi-erect, and semi-erect ears that half-drop to the front of the head.

The head is fresh and well defined, with a broad head that makes the head look quite large. Ears hang moderately on the sides of the head and slightly back. The eyes are of moderate size, mostly brown, yellow or black in color and have a very sociable demeanor. The neck is of moderate length and not too prominent. Ribs well extended, both shoulders long and slightly sloping. Thick chest of good width and depth. Front feet straight from below the shoulders to the ground, toes densely arched. Rear ankles moderately bent, limbs of moderate length, well balanced with all parts of the body.

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Labrador - Baidu Encyclopedia