All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Your question covers two points:
A - Ruling on such products.
B - Ruling of selling such products to the one who feeds dogs, pigs or the like.
To answer the first point, production of such food is permissible as long as it does not contain anything that is forbidden to be sold in Islamic Sharee'ah, such as blood.
Imam Ibn Hajar reported that 'All the Muslim scholars have agreed that selling blood is forbidden.'
As for the second point, selling such products to those who feed dogs, cats and other venerable animals, is permissible since feeding such animals is required in the Sharee'ah. If one keeps the animals, having them is forbidden in the Sharee’ah (e.g. dogs) because he will bear the sin. Selling products to feed pigs is forbidden since pigs are despicable and the Sharee'ah wants them to be killed.
Allah knows best.