Your dog's heart rate is an indicator of his health as well as of his mental state. The dog's heart rate will be higher when he is running or playing, or when he is upset or stressed; and it will be lower when he is calm and relaxed or resting. Even though it will change throughout the day depending on circumstances, a dog's heart rate has a normal and healthy ideal range.
Normal Heart Rates
Your dog's normal heart rate depends on his breed, size, age and health, but ideally it should fall within a normal range. For dogs, this normal range is wide, from 60 to 160 beats per minute. Large dogs have a slower heart rate than smaller dogs. For example, the normal heart rate for dogs who weigh more than 30 pounds is 60 to 120 beats per minute, while in dogs under 30 pounds and in puppies the normal rate is 120 to 160 beats per minute. Speak to your vet to determine a probable base heart rate for your dog, then check your dog's resting heart rate occasionally.
Abnormal Heart Rates
A heart rate slower than 60 or higher than 160 beats per minute warrants immediate attention from your veterinarian. It could signal a number of serious health problems, such as heart failure, low blood sugar, dehydration, anemia and hypothyroidism.