12.5 year old dog not eating meals but eating treats.

My 12.5 year old female spaniel has been acting oddly lately and I'm very concerned. Since around November, she started going off the tidbits she'd usually enjoy. (A corner of toast, raspberries things like that) but she was eating well. Just before Christmas she started fussing over getting started on eating at every meal (we've always fed her a daily allowance over three meals a day as our other dog has chronic pancreatitis). A month ago she decided she wasn't going to eat her dry food anymore. Nothing would convince her to eat it, so we changed to another brand. This went well for a week or two. Then she decided she didn't want to eat that brand anymore either and went off it completely. So we tried another brand of dry food, and she refused that too. Wouldn't even have a bite. We even tried two different food toppers but she wouldn't touch it. So we moved her to wet food. She ate that just fine for about ten days and now she's refusing to eat that too. We've tried sprinkling in treats and chicken and she'll just pick them out and leave the rest. Thing is - she asks for food and gets excited for it, but as soon as it's put down, she turns her nose up and will not eat it. She's still eating treats and getting hyped up for them like she always did too, but nothing seems to work with getting her to eat meals properly. I'm so stressed out and worried about her. She's been seen by a vet, who examined her and said there was no apparent cause for concern in her stomach/abdomen and she had some blood tests which came back with no cause for concern either - other than her ATL level was a little high but the vet said it's nothing that wouldn't be expected for a dog of her age and is unlikely to cause her symptoms. She's had no D&V at all. Drinks, pees and poops normally. She's more sleepy than before and not quite as bouncy but again, nothing that I wouldn't expect for her age. I will say that she doesn't have the best teeth, so I'm worried it could be something going on there, but she will happily eat hard and chewy treats, which wouldn't make sense if she's not eating soft wet food because of tooth pain. She's also taking Metcam/Loxicom for osteoarthritis, but she's been on this since January and this rejection of meals has only been happening for the last 20 days or so. Our vet has offered an ultrasound to see if there's anything untoward going on internally, and obviously there's the option to get her teeth looked at under a general aesthetic but I really don't want to put her through that unnecessarily. So I'm here to ask - has anyone experienced this before? And if so, what was the cause, and what can I do to help my girl? Any advice is appreciated.

Hello - and yes, I have seen this.  At risk of coming across as anthropormorphic, imagine that you are feeling a little bit off - not 'needs to be in Hospital' off, but but below parr - say you've got some ache or pain, or something is worrying you.   And you don't feel like eating.  But then someone puts something absolutely delicious - or just different - down in front of you, so you try a little bit.  And it might be nice.  But then you remember that you're not really feeling hungry.  I wonder if this is what you may be seeing.  So - what might cause it? I wonder whether arthritic pain has been completely ruled out.  I also wonder about pancreatitis (which can require extra bloods or an ultrasound to diagnose and doesn't always get an abdominal pain flinch on examination) or even dental disease.   An ultrasound doesn't usually require an anaesthetic.  Non steroidal anti-inflammatories like Metacam can lead to gut ulcers in some patients and these do develop quite slowly.  This would be unusual, but I dont think it can be worn out.   It sounds as though your vet is working well on this case and is in a better position to make reccommendations than I am, as they have all the information, examinations and findings available to them.  Please will you let us know how you get on?

Typo:  i dont think it can be ruled out (from what you've said - again, your vet has more info than me)