Musar zu Schemot 11:7

He also diminishes his stature as a human being thereby [(by speaking lashon hara)] until he emerges "worse than a dog," as Chazal have said (Pesachim 118a): "One who speaks lashon hara … deserves to be thrown to the dogs, it being written (Shemoth 23:1): 'You shall not receive a false report,' which is read as you shall not spread, which is preceded by (Ibid. 22:30): '…to the dog shall you throw it.'" The rationale is obvious, as written by the Maharal of Prague: "For the dogs guarded themselves when necessary, from 'sharpening their tongues,' as it is written (Ibid. 11;7): 'And against all the children of Israel, a dog shall not sharpen its tongue' — and he [(a human being)], whom the L-rd accorded understanding and knowledge could not restrain his yetzer from this [(lashon hara)] — wherefore he is 'worse' than a dog."

He also brings himself to eminence in this world, as it is written in Mechilta, Parshath Mishpatim on Shemoth 32:30: "And flesh torn in the field you shall not eat. To the dog shall you throw it" — to teach us that the Holy One Blessed be He does not withhold reward from any creature, as it is written (Shemoth 11:17): "And to all the children of Israel a dog will not sharpen its tongue." Now is this not a kal vachomer [i.e., Does it not follow a fortiori]: If it is so [i.e., that He does not withhold reward] from an animal, how much more so from a human being!

The Maharal of Prague gives another reason. The dogs guarded themselves when necessary [at the exodus] from barking, as it is written (Ibid. 11;7): "And against all the children of Israel a dog will not sharpen its tongue." Yet he [man] whom the L-rd has accorded understanding and knowledge cannot keep his yetzer from doing so — wherefore he is worse than they!

The Midrash tells us that the number of Israelites would never be fewer than 600,000. Dogs is a hyperbole for קליפה. Our sages in Baba Kama 60 say that it is the dogs that call out: "the angel of death is coming!" When the firstborn of Egypt were slain and the Jews were about to leave Egypt, the Torah described the dogs as having remained silent towards the Israelites (Exodus 11,7). The hyperbole used in the Midrash saw Jacob as appointing the dogs as guards over the sheep i.e. Jewish people in exile, so that they would not become further infested with the pollutants of the original serpent. The opinion cited that he used 1,200,000 dogs is in accordance with the view expressed in Shabbat 88 that when Israel committed the sin of the golden calf, 1,200,000 destructive angels descended in order to remove each man's jewelry from him. This had been bestowed on them at the time Israel volunteered to accept the Torah. Jacob wanted to make these dogs subservient to the flocks, i.e. the Jewish people, in order to fulfil what is written in the verse in Proverbs 16,7: "When a man's ways please G–d, He makes even his enemies be at peace with him." We have stated that צאן is an allusion to the people of Israel. An interesting mnemonic note may be the halachic term צאן ברזל, which is used for inalienable property of the wife which returns to her family regardless of any rights of the husband. The four wives of Jacob produced the twelve tribes. Their names were: בלהה, רחל, זלפה, לאה. The first letters of their respective names spell ברזל, something that will endure under all circumstances.