What happens to dead pets? do they go to heaven?
What is heaven? “state of supreme, definitive happiness", “communion of life and love with the Trinity, with the Virgin Mary, the angels and all the blessed" (CCC 1024).
This state presupposes rational knowledge and love which animals do not posses and what this means is that this heaven defined cannot be experienced by any non-human animal.
Pets depend on their material makeup, they do not continue to exist after death as human souls do. They therefore cannot exist in heaven before the return of Christ on earth. However, when Christ creates the “new heaven and new earth" (see CCC 1043; 2 Pet. 3:13; Rev. 21:1), the pets who exist at the time of his return might be able to exist therein. Not in the sense of experiencing the Beatific Vision like humans will, but might be able to live on the new earth. I said “pets who exist at the time”, because those who have died cannot resurrect since they do not have rational souls.
The Church has never given any teachings concerning pets in heaven. Any response will be appealing to reason and not to any predefined teachings of the Church.