Final answer:
The heart rates of small breeds of dogs are generally higher than those of large breeds of dogs due to variations in size, body mass, and metabolism.
Step-by-step explanation:
The heart rates of small breeds of dogs are generally higher than those of large breeds of dogs. This is because smaller dogs have faster metabolic rates and higher resting heart rates.
For example, a small breed like a Chihuahua may have a resting heart rate of around 100-140 beats per minute, while a large breed like a Great Dane may have a resting heart rate of around 60-100 beats per minute.
This difference in heart rate is due to variations in size, body mass, and metabolism between small and large dog breeds.