Factors such as individual variability, breed-specific traits, overall health, and lifestyle can influence a dog's physical characteristics and behavior, making it challenging to accurately estimate age solely based on these attributes.
As a result, the most reliable method for determining the approximate age of a dog, including a rescued cocker spaniel, is through veterinary assessment. A veterinarian can assess various factors such as the dog's teeth, joints, and overall condition to provide a more accurate estimate of its age.