my 6-year old chihuahua seems sad

Question
Hello! Thank you for taking the time to read this. 3 days ago my chihuahua Ella seems to be unusually sad and I cannot figure out why this may be? I also have a 6 year old cat and since they grew up together, they love each other very. Our routine has not changed, I am home alot doing work for graduate school, so I am not consistently gone every day. She is still very loving and affectionate towards me, but has significanly had a decrease in energy and just isnt her perky self. Although I am home for the most part i am on the computer doing work for hours at a time, but Ella is always right next to me laying on the couch protecting her bone from anyone who enters the room not including myself. Ella still displays love, sleeps right next to me every night, but has not had her upbeat personality. In the past 3 days she seems to be sleeping alot and everytime I want to play with her so is not as enthusiastic as she normally is, this is the same behavior with food and treats. Ella lives for food and treats and when she knows she will be getting a treat or her breakfast and dinner, she usually cannot control her excitement. Since I've noticed this "sad" behavior I have made it a priority to give her even more attention than I usually give her. I feel as though this does not have anything to do with me due to the fact that our routine has not been changed for quite some time and still cries and howls when I go upstairs for a period of time or when coming home if I do not go downstairs immediately to see Ella and Puss they both explain they are upset and will not stop until I do go sownstairs. I do not know what possible cause could be making her act like this, and to see her sad it very upsetting to myself. I hope that this is a small temporary problem and will be back to normal soon. Any help would be great, It kills me to see her sad  :( Thank you so much for taking the time to read this, I appreciate it very much. Hope to hear from you!
Sincerely,
Ashley Smith


Answer
Hi Ashley...

First off, my apologies for not having written you sooner.  There must have been a glitch with AllExperts as I didn't realize that I had a question pending until after I had answered another question last night that just came in - when I sent off the answer to that question, my AllExperts page showed that your question was pending.

Ashley, it concerns me that Ella is showing these changes that make her appear to be sad or depressed. The first thing that comes to my mind is that before we conclude that she's "sad", you need to rule out medical causes for these very relevant changes.  Has Ella had blood work done ever?  I strongly suggest that you make an appointment with a qualified veterinarian and have her examined and a full blood panel done.  There are many medical conditions that present with some of the symptoms that you have mentioned and you really need to rule out a medical condition as being the cause.  It's much better to catch things early than to let things "ride" until her symptoms progress.  She's right at the age where I like to have a full blood panel done on my dogs so that I have the information for comparative purposed later and so that I can catch little problems before they become big problems.

I will be thinking of you and Ella and I hope that you write back and let me know how things went with the veterinarian and how Ella is doing.

Jo Ann