You have a 20% lower chance of seeing Pet Food if you're crafting when the recipes reset.
Which means that if you want to maximize your chances of getting a pet recipe you can do three things:
1) Sync the crafting so that the changes are aligned so you can see all four groups each day. For me, as another player noted, that meant spending 50 diamonds to reset the crafting cycle to 3pm. I come on at 7am, and have 2 hours before the next cycle. I then check at 9am, and 3pm.
2) Craft all the buildings of which you can have only one. The mermaids, and other evolving buildings and the chess sets. Once you craft each of those they are no longer offered, thus freeing the slot for something else and improving the odds of getting what you want (in this case pet food).
3) Make sure you finish and collect whatever is being produced before the cycle is reset. Sometimes this means you will need to consider if using time instants is worth the extra chance or not. Again, this frees up a slot that wouldn't change if you were in the midst of crafting the item or had finished it but not collected it.
I generally see pet food at least once a day or perhaps day and 1/2. So I get about 4 - 5 per week. Since I use 3 on my phoenix for the tournament and 1 or 2 to make troops with my brown bear, I have just enough. I too would like more, but at least I seem to be able to keep up if I watch the crafting cycle as it is.
AJ