3 yr old cat lethargic/not eating

Question
My inside cat (Jupiter) recently turned 3 yrs; he is an American short hair. He is neutered, up on his shots and has never been sick. We have one other cat who spayed, up on her shots and they have never had any problems. We got a puppy (half lab half retriever) a few weeks ago and he is getting is puppy shots.

Two days ago I noticed Jupiter was acting differently. When dinner time came he would just sit there and watch our other cat ear or just ignore the food. I picked him up and put him near the food and then he started eating. After that, I began watching him more closely and he isn't waking me up in the morning for breakfast, when I pet him he isn't purring (and he as a purr that can shake the house and comes easily for him) and then this morning he just ignore his breakfast all together. When I went to pet him he whimpered at me and just laid his head back down to sleep.  I haven't seen him drinking any water but I do believe he used the litter box this morning.

I plan on taking him to the vet this afternoon but I'm very scared to loose him and don't know what this might be or if it's serious.

Thank you for any help you can offer.

Answer
Sarah,
you take very good care of your cats. He may just have a digestive upset from the food he is eating. He might have tusseled with the puppy and have a sore spot on him.

Don't work yourself into a tizzy over something you can't control until the vet sees him. You will only upset him. Take that energy and use it to think wonderful, healing thoughts that you send out to Jupiter.

Tell him what a great, vibrant, healthy cat he is and just keep repeating that until you know what is going on, and then continue thinking those thoughts.

You might want to change their food as well once he is past this. My cats have eaten Science Diet for over 25 yrs and they never, ever get sick. If your food is from the grocery store, or even Iams, then it's not made the same each time and can make your pet sick from sudden changes in their formulas.

So get past today at the vets and then make a plan to switch them over slowly.
Please let me know what you find out at the vets.