A dog will teach you unconditional love.

In the pre-vedic Era in Hindu mythology!

Dattatreya, or Sri Datta, as he is also referred to, is a Hindu deity who is also regarded as an aspect of the Divine Trinity of Brahma, Vishnu and Shiva. The name “Dattatreya” is derived from two Sanskrit words, Datta (which means “given”) and Atreya (which refers to the sage Atri, Sri Datta’s biological father). In the Nath tradition, Dattatreya is considered to be an avatar or reincarnation of Lord Shiva.

 

In the pre-Vedic era, dogs were regarded as auspicious. It was believed that deities assumed the form of dogs.
These animals were also often linked to fidelity and Veera, the quality of great courage, closely associated with warriors. Dogs can be both wild and tame, thereby representing the qualities of fidelity and devotion.
The dog is one of the most sublime symbols of the Vedic system. The dog is capable of sharp auditory capability and has a perception far more advanced than that of human beings.
Shri Guru Datta is commonly portrayed as being accompanied by 4 dogs of 4 different colors. These 4 dogs represent the following: The 4 Vedas: Rig Veda, Sama Veda, Yayur Veda and Atharva Veda 
The 4 Yugas: SatyaYuga, Treta Yuga, Dwapara Yuga and Kali Yuga
The 4 states of the Word: Para (beyond), Pasyanti (perception); Madhyama (conception), Vaikhari (vocal) The 4 states of Existence: Existence, Awareness, Thought and Speech or Action.
The Kamadhenu cow is symbolic Panchabutas, the four dogs are inner forces of a human being: Iccha, Vasana, Asha and Trishna.