Odd symptom after eating in my Dog

Hello Vets, Thank you in advance. Is there anyone here that has heard of a digestive or metabolic issue connected to eating that causes panting ? My dog is fine all day long . During the day , he nibbles. He does not really like dog food , so he will get a bite here and there or a few kibbles . At night I cook for him, but, I always fix healthy food . A small amount of meat for protein , rice and lots of green beans or peas. About 3 hrs after he eats a full meal , he begins to pant, he will also lick his legs. His Vet has no clue what is wrong . They ran numerous tests . He will fall asleep , and is fine , except if I wake up during the night , I might catch him licking his legs. I wonder if he has an allergy to food , or a digestive issue and the panting and licking could be from discomfort ? He is fine during the day . He looks healthy , smooth fur, plays , eats and potties without issue . He is a 7 yr old rat terrier , he takes phenobarbital , 30 mg twice daily for very infrequent seizures.  His blood is checked several times a yr .  Other than slight elevation of ALP due to phenobarbital , liver values fine . Thyroid panel normal .  Any information or advice is greatly appreciated. Thanks to all .

Hello - what an interesting set of symptoms.  Usually seven years would be quite old for a skin allergy develop- although it can - but it doesn't really explain the other symptoms.  Indeed, allergy may be on your vets' 'possibilities' or 'differentials' list but, depending on your dogs' presentation, may be quite far down it.  A common cause of both panting and licking is pain.  Depending on what is causing it, pain does not necessarily show up on blood tests (pancreatitis, for example, would often need specific laboratory-run tests and arthritis is diagnosed from radiographs of appropriate joints) - so this could be an avenue that your vets may want to explore.  Animals mask pain quite well from their owners, so it is not unusual that owners do not think that their dog is in pain.  Tumours, unfortunately, might cause abdominal pain and thereby similar signs.  A common response to this is to say, 'why are they licking there?' - dogs sometimes lick places that are convenient, in the appropriate general direction.  Other differentials may include a long list from blood loss through the spleen, to gut-ache as a result of the beans / gas (particularly as dogs' metabolism can change as they get older).  Heart and lung disease can also lead to panting.   Thus, the list of differentials is varied and long, but an examination and a few short tests might help your vet to start to narrow the possibilities down.

Finally, a word about green beans - some sources of green beans are actually quite high in salt.  Seizures and tremours, a lack of energy, stomach pains, 'headaches,' loss of appetite and respiratory distress can be signs of salt toxicity.  This is unusual, but may be worth considering and again, blood tests can be done for it.   Extreme thirst can often be seen in these cases.

A good approach would be to say to your vet: 'What could still be going on here?  Which possibilities are most likely?  Which are easiest to rule out?' and to make a plan from there.