Zoroastrianism is one of the most ancient religious teachings, which originated on the territory of the present-day Transcaucasian countries, Iran, and Afghanistan. The calendar of the adherents of this religion included holidays and days of sorrow associated with it. "Dog days" is one of the four annual fasts of the Zoroastrians.
According to the teachings of Zoroastrianism, after the incarnation of our world by the Wise Lord, Ahura Mazda, the all-destroying spirit of Angra Mainyu with hordes of his henchmen, the devas, invaded it. At first he tried to destroy the fire, but this could not be realized, the fire only began to be accompanied by smoke. Then he broke the sky and the space beneath it, turned the Earth into a desert, desecrated the water, making it bitter and unfit for drinking, destroyed the first tree - Haomu, the first animal - the bull Efhodat and the man - Gayomart. Ahura Mazda with the forces of light then restored everything, but this event marked the end of the era of Creation and the spring of the world, and the beginning of the era of Mixing of light and darkness in every creation, in which we now live.
In memory of the battle of all elements against Angra Mainyu (or Ahriman), there was one of four annual fasts in the ancient Iranian calendar. It was appointed at the time when the Sun passes from the second to the seventh degrees in the zodiacal constellation Cancer. In our calendar, this time corresponds to the period from 23 to 28 June. Fasting reminds of how the Wise Lord, one after another, conquered the elements from the powers of darkness and gave them guards for protection. These guardians are dogs. The element of fire, the only one remaining undefiled, corresponds to 1 ° Cancer - it is guarded by a fox or a fiery dog. Guardian of the sky (Cancer 2 °) - heavenly dog or raven. The earthly element (Cancer 3 °) is protected by a dog. The most defiled was the water element, which is still bitter in the oceans. Its guardian is a beaver, a water dog, and by the time of fasting this element corresponds to 4 ° Cancer. Plants (5 °) are called upon to protect the raccoon, animals (6 °) - the mongoose, and people (7 °) - the hedgehog.
That is why fasting was called "dog days" and these days are considered days of mourning. The symbolic meaning of fasting is the protection of the elements from dark forces and the purification of thoughts, as a way of purifying the world around us. It is noteworthy that not only Zoroastrians, but also the Romans preferred to wait out these days in a variety of activities and even dissolved the Senate for a vacation - Caniculus, by the name of the constellation of the Hounds of the Dogs.