No matter how a bitch acts or looks, not even experts can be 100-percent sure about her general fertility and an estimated puppy count.
Source: Breeding Business, Link. There are several factors influencing the number of puppies a given female will have in her next litter. These include:
- The breed
- Size of the female
- Coefficient of inbreeding
- Age of the bitch
- Health of the dam
- Diet of the dam
- Age of the stud