older male cat & constipation

Question
  Hi Jen;
          Appreciate your time&dedication,ty!
             I have an older male long hair I picked up at our Humane Society nearly 13 years ago,and they believed he may have been 5-7 years old at that time.
                 Medication he is on is Methimazole 5mg.,&Benazepril 5mg...half a Meth.,& quarter a Ben., daily.
                      He has been such a good pet,lost his hearing a year or so ago,but otherwise in good health,except now he is not eating & is skin&bone to begin with. He also seems to get verbal more & especially when I open the fridge...just don't know what he wants...;o(
  He walks around like he is needing to go to the bathroom,but I'm sure their is nothing to release...possible constipation?
  Could you please let me know what signs I should b looking for that would indicate he may be suffering more than I realize,and what I could do for him to get him eating & going to the bathroom.
         Any advice would be appreciated,and thank-you very much!
                                  Craig  

Answer
I would recommend a trip to the vet for an exam and bloodwork.  I would be concerned that his methimazole may need to be adjusted as it is either not enough or too much and affecting his kidney function.  Many cats with hyperthyroidism have concurrent kidney disease which often causes the appetite to decrease.  He may benefit from a SQ fluid treatment and a B12 injection.

If he is not eating, he will not have much of a BM.  However, he should still be urinating.  If he is not urinating, that is an emergency!  

You can try offerring him some meat baby food or cooked chicken breast or tuna to see if that interests him.  You can also offer him pedialyte to see if he will drink that to help prevent dehydration.