I use a small khajiit building as a dog house, then there's a food dish with yellow stuff in there. The Markarth Bear-Dog has a downward sniff animation, if you place the food dish just right it looks like he's eating out of it.
Thank you everyone for your creative ideas! i found out last night, the polished ivory.. um whatever it is, looks like a great chew bone for a large dog. Found a bowl with oatmeal it says.. was way too small but i think i'm on the right track. Maybe a stew pot with stuff in it.
Maybe the designers will come up with actual pet toys. Even the ability to play fetch with them! That was a fun option in wow.
The 2 balls of yarn could work (Though don't give cats yarn to play with in real life!), I also like to use some of the bowls with food in them for pets. Like Alinor Bowl Millet, Redoran Bowl Saltrice Mash, Dres Bowl Saltrice Mash, Bowl of Grubs etc.
Other than the polished ivory for dog bones, you could probably clip Bear Skeleton, Picked Clean and Unidentified Fargrave Bones into the floor/ground so only a smaller bone is visible.
On the subject of food, UESP tells me there’s a green recipe for ‘Solitude Trough, Empty’. I’ve also used the wheat piles that drop during the Witches Festival as mount fodder.
Maybe some of the flatter pillows would work as a cat bed?