Jack Russel Terrier slowing down

Question
We have a JRT that is only just over 5 and half years old. He has started slowing down, though recently. I'm not sure why the sudden change. His diet is the same. We got another dog around Christmas of the last year, but he gets along with her well.  He has started to sleep under the furniture more, and not coming out that often to hang out with the family as he used to. But, all of his other characteristics are the same as always. He eats and drinks normally, and he will play with our other dog occasionally. We are just concerned about him not being as social as he once was. Is this normal, or is this something we should be concerned about. He did have a check up a couple of months back and everything checked out great. Thanks!

Answer
Hi Jennifer,

I would take him back to the vet for another check up. I know you went a couple of months ago but it sounds like he's not feeling well. Wouldn't it be nice if they could tell us? They will take him temp and probably a blood sample. Lyme disease has been prevalent this year even with preventatives, and it can appear within a week.  It makes dogs sluggish, and just not right. It is treatable with antibiotics. Jacks are so wonderful and social I bet he really wants to play and gets that boost of energy you see, but then tires out quickly. It could really be any number of things, but any change is a sign of something. Very best of luck Jennifer!