They never denied Him. We did. And unfortunately, because man and the animals are united as one in Creation (God created all of us), they suffered due to our sin and disobedience. We owe them kind and humane treatment because our disobedience in the Garden of Eden brought sin, disease, cruelty and death upon ALL of God’s Creation, them as well as us.
But animals never denied Him.
Listen to the words of Saint Paul, from the Epistle for the 4th Sunday after Pentecost (Traditional Roman Catholic Mass Propers):
Romans 8: 18 - 23
Brethren, I reckon that the sufferings of this time are not worthy to be compared with the glory to come, that shall be revealed in us. For the expectation of the creature waiteth for the revelation of the Sons of God.
For the creature was made subject to vanity, not willingly, but by reason of him that made it subject in hope; because the creature also itself shall be delivered from the servitude of corruption, into the liberty of the glory of the children of God. For we know that every creature groaneth, and travaileth in pain, even till now; and not only it, but ourselves also, who have the first fruits of the Spirit, even as we ourselves groan within ourselves, waiting for the adoption of the sons of God, the redemption of our body; in Christ Jesus Our Lord.
All praise to the Lord Jesus Christ! For by dying He has destroyed death, and shall come again in glory, restoring all Creation unto Himself, and they shall not hurt nor destroy in all His holy mountain! Just as through the first Adam all died, so through the second Adam…the Lord Jesus Christ…ALL shall be made alive!