However, it's important to note that:
* Individual variation exists: Some males might reach maturity earlier or later than this range.
* Fertility doesn't equal maturity: While a male might be fertile, he may not be physically or emotionally mature enough to be a responsible stud dog.
* Spaying/neutering: If you plan to neuter your male cocker spaniel, you should discuss the best age with your veterinarian.
It's always best to consult with your veterinarian for the most accurate information about your individual dog's development and fertility.