45天小狗一次吃多少狗粮

This question is difficult to answer without more information about the specific dog, including its size, breed, age, and activity level. Generally, the amount of food a dog should eat per day depends on these factors, as well as its overall health and any underlying medical conditions. It is best to consult with a veterinarian or use a dog food calculator to determine the appropriate amount of food for your dog.