Shavua Tov. Among the seventy four Mitzvot mentioned in today’s Parsha, several of them deal with animals.
We have the Mitzva of שילוח הקן, sending away the mother bird, while taking away the eggs or chicks. There is also the commandment to help the donkey who cannot hold the heavy weight on its back, and collapses. We have to help the animal to its feet and put back the load.
There is also the prohibition of muzzling an ox or donkey while it is plowing.
The Rambam in מורה נבוכים speaks about some of these laws, and addresses שילוח הקן as well as the prohibition of אותו ואת בנו, slaughtering a mother and her offspring on the same day. The wording of the Rambam is, ״כדי שלא תצטער האם בלקיחת בניו״, that we are not to allow the mother animal to feel sad when her children are taken away.
The Rambam seems to acknowledge that there is a real mother instinct in animals, and they experience the emotion of sadness.
All of this teaches the importance of צער בעלי חיים, not causing pain to animals, and treating them kindly.