A person’s heart can at times be compared to a dog. Just as one must muzzle their dog so that it will not do harm, so too, must an individual muzzle their heart.
– Reb Mendel Futerfas
The Zohar states that a “kelev,” a dog, is called so because it is kulo lev, completely heart and never satisfied. We must make sure to not be overly indulgent in the world around us.