Depending on the size of our four-legged friend, his pulse beats at a frequency of 60 to 140 beats per minute. A healthy person's pulse is 60-80 beats per minute, so a dog's heart can beat almost twice as much. ¹⁾

Dogs' eyes contain a special membrane that allows them to see better in the dark. ²⁾

Color is discerned by the nerve cells in the eye. The retina of the eye has two main types of cells: rods, which detect light levels and motion, and cones, which differentiate colors. Dogs possess only two types of cones and can only discern blue and yellow colors. This limited color perception is called dichromatic vision. ³⁾

The longest-lived (as documented) Australian shepherd dog named Bluey. He worked as a shepherd for 20 years. He died at the age of 29 years and 5 months. ⁴⁾

Dogs and humans have the same REM sleep type, so dogs can have dreams. The movements that occur during sleep are signs that your pet is dreaming. ⁵⁾