SB 7.14.9

mṛgoṣṭra-khara-markākhu-
 sarīsṛp khaga-makṣikāḥ
ātmanaḥ putravat paśyet
 tair eṣām antaraṁ kiyat
Word for word: 
mṛga — deer; uṣṭra — camels; khara — asses; marka — monkeys; ākhu — mice; sarīsṛp — snakes; khaga — birds; makṣikāḥ — flies; ātmanaḥ — of one’s self; putra-vat — like the sons; paśyet — one should see; taiḥ — with those sons; eṣām — of these animals; antaram — difference; kiyat — how little.
Translation: 
One should treat animals such as deer, camels, asses, monkeys, mice, snakes, birds and flies exactly like one’s own son. How little difference there actually is between children and these innocent animals.
Purport: 

One who is in Kṛṣṇa consciousness understands that there is no difference between the animals and the innocent children in one’s home. Even in ordinary life, it is our practical experience that a household dog or cat is regarded on the same level as one’s children, without any envy. Like children, the unintelligent animals are also sons of the Supreme Personality of Godhead, and therefore a Kṛṣṇa conscious person, even though a householder, should not discriminate between children and poor animals. Unfortunately, modern society has devised many means for killing animals in different forms of life. For example, in the agricultural fields there may be many mice, flies and other creatures that disturb production, and sometimes they are killed by pesticides. In this verse, however, such killing is forbidden. Every living entity should be nourished by the food given by the Supreme Personality of Godhead. Human society should not consider itself the only enjoyer of all the properties of God; rather, men should understand that all the other animals also have a claim to God’s property. In this verse even the snake is mentioned, indicating that a householder should not be envious even of a snake. If everyone is fully satisfied by eating food that is a gift from the Lord, why should there be envy between one living being and another? In modern days people are very much inclined toward communistic ideas of society, but we do not think that there can be any better communistic idea than that which is explained in this verse of Śrīmad-Bhāgavatam. Even in the communistic countries the poor animals are killed without consideration, although they also should have the right to take their allotted food with which to live.