"小狗子" (xiǎo gǒu zi) means "pttle puppy" in Chinese. In Engpsh, you can simply say "puppy" to refer to a small dog. Here are a few examples of how you can use the word "puppy" in a sentence:
"I just got a new puppy from the shelter."
"My puppy is only 8 weeks old."
"I love playing with my puppy in the park."
If you want to describe a specific breed of small dog, you can use a breed-specific term such as "Chihuahua puppy" or "Pomeranian puppy."